[Federal Register Volume 63, Number 90 (Monday, May 11, 1998)]
[Rules and Regulations]
[Pages 25996-26016]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-12296]
[[Page 25995]]
_______________________________________________________________________
Part III
Department of Energy
_______________________________________________________________________
Office of Energy Efficiency and Renewable Energy
_______________________________________________________________________
10 CFR Part 430
Energy Conservation Program for Consumer Products: Test Procedure for
Water Heaters; Final Rule
Federal Register / Vol. 63, No. 90 / Monday, May 11, 1998 / Rules and
Regulations
[[Page 25996]]
DEPARTMENT OF ENERGY
Office of Energy Efficiency and Renewable Energy
10 CFR Part 430
[Docket No. EE-RM-94-230]
RIN 1904-AA52
Energy Conservation Program for Consumer Products: Test Procedure
for Water Heaters
AGENCY: Office of Energy Efficiency and Renewable Energy, Energy.
ACTION: Final rule.
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SUMMARY: The Department of Energy (DOE or the Department) is amending
its test procedure for water heaters. The first-hour rating for
storage-type water heaters is revised to more accurately measure large
storage-type water heaters. Also, electric and gas-fired instantaneous
water heaters are rated at the maximum flow rate to distinguish them
from storage-type water heaters.
EFFECTIVE DATE: This rule is effective June 10, 1998.
FOR FURTHER INFORMATION CONTACT: Terry Logee, U.S. Department of
Energy, Energy Efficiency and Renewable Energy, Mail Station EE-43,
Forrestal Building, 1000 Independence Avenue, S.W., Washington, D.C.
20585-0121, Telephone (202) 586-1689, FAX (202) 586-4617,
terry.logee@hq.doe.gov.
Eugene Margolis, Esq., U.S. Department of Energy, Office of General
Counsel, Mail Station GC-72, Forrestal Building, 1000 Independence
Avenue, S.W., Washington, D.C. 20585-0103, Telephone (202) 586-9507,
FAX (202) 586-4116, eugene.margolis@hq.doe.gov.
SUPPLEMENTARY INFORMATION:
I. Introduction
A. Authority
B. Background
II. Discussion of Comments
A. General Comments
B. Product Specific Comments
1. Instantaneous Water Heaters
2. Storage-type Water Heaters with Rated Storage Capacities Less
than 20 Gallons
3. Definitions
4. Heat Pump Water Heaters
5. First-Hour Rating for Storage-type Water Heaters
6. Installation of Under-the-Counter and Counter-Top Water
Heaters
7. Test Conditions
8. Cost-Based Correction Factor for Fossil-Fueled Residential
Appliances
III. Procedural Requirements
A. Review Under the National Environmental Policy Act of 1969
B. Review Under Executive Order 12866, ``Regulatory Planning and
Review''
C. Review Under the Regulatory Flexibility Act of 1980
D. ``Takings'' Assessment Review
E. Federalism Review
F. Review Under the Paperwork Reduction Act
G. Review Under Executive Order 12988, ``Civil Justice Reform''
H. Review Under the Unfunded Mandates Reform Act of 1995
I. Congressional Notification
I. Introduction
A. Authority
Part B of Title III of the Energy Policy and Conservation Act, as
amended (EPCA or the Act), establishes the Energy Conservation Program
for Consumer Products other than Automobiles (Program).1 The
products currently subject to this Program include water heaters, which
are the subject of today's Final Rule.
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\1\ Part B of Title III of Energy Policy and Conservation Act,
as amended, is referred to in this Final Rule as ``EPCA'' or the
``Act.'' Part B of Title III is codified at 42 U.S.C. 6291-6309.
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Under the Act, the Program consists essentially of three parts:
testing, labeling, and the Federal energy conservation standards. The
Department, in consultation with the National Institute of Standards
and Technology (formerly the National Bureau of Standards), is required
to amend or establish test procedures as appropriate for each of the
covered products. Section 323 of EPCA, 42 U.S.C. 6293. The purpose of
the test procedures is to produce test results that measure energy
efficiency, energy use, or estimated annual operating cost of a covered
product during a representative average use cycle or period of use. The
test procedure must not be unduly burdensome to conduct. Section
323(b)(3) of EPCA, 42 U.S.C. 6293(b)(3).
Beginning 180 days after a test procedure for a product is
prescribed, no manufacturer, distributor, retailer, or private labeler
may make representations with respect to the energy use, efficiency, or
cost of energy consumed by such products, except as reflected in tests
conducted according to the DOE procedure. Section 323(c)(2) of EPCA, 42
U.S.C. 6293(c)(2).
Furthermore, DOE is required to determine to what extent, if any,
an amended test procedure would alter the measured energy efficiency or
measured energy use of any covered product as determined under the
existing test procedure. Section 323(e)(1) of EPCA, 42 U.S.C.
6293(e)(1).
B. Background
Today's Final Rule amends DOE's test procedure for water heaters by
revising the method used to determine the first-hour rating of storage-
type water heaters, adding a new rating for electric and gas-fired
instantaneous water heaters, and amending the definition of a heat pump
water heater.
On March 23, 1995, DOE published in the Federal Register (60 FR
15330) a Notice of Proposed Rule and Public Hearing on proposed
amendments to clarify the water heater test procedure and requested
data, comments, and information regarding its applicability and
workability. The Department conducted a public hearing on July 12,
1995, and a public workshop on February 12, 1997, and requested written
comments.
The proposed amendments to the water heater test procedure included
revisions to make the water heater test procedure applicable to
electric and oil-fired instantaneous water heaters; coverage for
testing storage-type water heaters with rated storage capacities less
than 20 gallons (76 liters); revision of the first-hour rating for
storage-type water heaters; amendment to the current definition for
heat pump water heater; and the addition of new definitions for heat
pump water heater storage tank, add-on heat pump water heater, integral
heat pump water heater, and solar water heater. In addition, DOE
requested comments on the adequacy of the test procedure for heat pump
water heaters regarding the use of a backup electric resistance
element(s).
II. Discussion of Comments
A. General Comments
Forty commenters submitted written comments in response to the
proposed rulemaking on water heaters. After reviewing these comments
and the comments presented during the public hearing, the Department
held a public workshop on February 12, 1997, to solicit additional
comments on the issues in the Proposed Rule. Workshop topics included
the daily hot water consumption of 64.3 gallons (243.4 liters) and the
thermostat setting of 135 deg.F (57.2 deg.C) in the existing test
procedure. The notice for the public workshop was published in the
Federal Register (62 FR 4202, January 29, 1997). Nine commenters
submitted written comments prior to and after the workshop. Those
written comments received prior to the workshop (from the Gas Appliance
Manufacturers Association [GAMA], February 12, 1997, Water Heater Test
Procedure Workshop Transcript [hereafter referred to as ``February 1997
Transcript''] at Appendix I; Electric Power Research Institute [EPRI],
February 1997 Transcript at Appendices E and J; and Controlled Energy
Corp. [CEC], February
[[Page 25997]]
1997 Transcript at Appendix H) were distributed to all participants at
the beginning of the workshop for inclusion in the workshop session.
During the rulemaking process, a number of commenters stated their
support of the EPRI recommendations on all issues. These commenters
included: Northeast Utilities Service Co., No. 11; The Dayton Power &
Light Co., No. 15; Utilities District of Western Indiana, No. 16;
National Rural Electric Coop. Assoc., No. 18; Decatur County REMC, No.
19; Pennsylvania Power & Light Co., No. 20; Central and South West
Services, Inc., No. 21; Centerior Energy, No. 22; Hawaiian Electric
Co., No. 23; Southern Company Services, Inc., No. 24; Potomac Electric
Power Co., No. 26; East Kentucky Power Cooperative, Inc., No. 34; Ohio
Edison Co., No. 39; Southern California Edison Co., No. 43; Duke Power
Co., No. 44; and Nevada Power Co., No. 45.
The following is a summary of the public comments, presented during
and after both the public hearing and the workshop, on each of the DOE
proposed amendments/revisions, and on other issues concerning the
existing test procedure.
On October 31, 1997, the comment period was reopened on the issues
of the maximum gallons (liters) per minute rating for electric and gas-
fired instantaneous water heaters and the energy factor of the heat
pump water heater storage tank. (62 FR 58923, October 31, 1997.)
B. Product Specific Comments
1. Instantaneous Water Heaters
a. Coverage of Electric and Oil-Fired Instantaneous Water Heaters.
The current test procedure does not address the testing of electric and
oil-fired instantaneous water heaters, because they are not defined in
the test procedure. In the 1995 proposed rulemaking for water heaters,
DOE proposed definitions for these two types of instantaneous water
heaters so they would be subject to the same test procedures as gas-
fired instantaneous water heaters (i.e., the first-hour rating test and
the 24-hour simulated use test).
GAMA agreed that electric and oil-fired instantaneous water heaters
should be covered in the test procedures. However, GAMA said it is
unaware of any residential oil-fired instantaneous models on the
market. (GAMA, No. 1 at 2 and February 1997 Transcript at 119.) Edison
Electric Institute (EEI), Bock Water Heaters (Bock), the Federal Trade
Commission (FTC), and the Oregon Energy Office (Oregon) also stated
that they know of no residential oil-fired instantaneous water heaters
on the market. (EEI, February 1997 Transcript at 119; Bock, February
1997 Transcript at 120; FTC, February 1997 Transcript at 120; and
Oregon, No. 51 at 3.) In response to the reopening notice of October
1997, Controlled Energy Corporation provided information on a kerosene-
fired instantaneous water heater sold by Monitor Products, Inc. (CEC,
No. 64 at 1.) The California Energy Commission (CAEC) also provided
information on one oil-fired instantaneous water heater manufactured by
Monitor Products of Princeton, NJ, which meets the definition in the
test procedure for the input BTU rating. The CAEC also informed DOE
that Monitor intends to introduce another smaller instantaneous water
heater soon, and the CAEC opposed the DOE withdrawing coverage for oil-
fired instantaneous water heaters. (CAEC, No. 68 at 1-2.)
Virginia Power stated that it does not support the testing and
rating of electric units because of the small variance in efficiency
among them. Virginia Power stated that electric units are not typically
compared to oil or gas-fired instantaneous water heaters. Virginia
Power claimed the incomparability is due to the difference in
utilization between gas-fired and electric instantaneous water heaters.
(Virginia Power, No. 50 at 2 and No. 66 at 3.) The Department
interprets this statement to mean that gas-fired models are for whole-
house applications, whereas electric models are for point-of-use
applications such as kitchen or lavatory sinks.
EPRI stated that neither the existing nor the proposed test should
be applied to instantaneous water heaters because a heating rating of
more than 150,000 Btu per hour is needed to satisfy whole-house
applications and all instantaneous water heaters for residential use
are below that heating capacity. EPRI claimed that an instantaneous
water heater should not have an efficiency rating because the
efficiency rating would falsely imply an equivalency with tank-type
water heaters. (EPRI, No. 56 at 11.)
The Oregon Energy Office suggested that an energy efficiency rating
for instantaneous water heaters is needed, and suggested that a test
procedure should be developed that would take into account the warm-up
and cool-down losses during a draw for all units (as well as the flue
and pilot light losses for gas-fired units). Oregon stated that the
procedure for instantaneous water heaters should not be the same as for
storage-type water heaters. (Oregon, No. 51 at 3.)
GAMA claimed for electric models that there are distinctions
between larger models intended for multiple points of use and smaller
models intended for a single point of use. GAMA suggested that DOE may
need to make distinctions between such units by creating separate
classes of instantaneous water heaters. (GAMA, No. 1 at 2.)
DOE believes that separate classes of electric instantaneous water
heaters would require technical data on these models, such as: (1) The
intended purpose of use; (2) the frequency of daily draws at the point
of use; (3) the average volume of each draw; and (4) the average amount
of the total daily draw. However, DOE believes that at the present
time, the development of separate classes of electric instantaneous
water heaters for residential application is not needed because, even
at the proposed maximum input power rating of 12 kW (40,944 Btu/h), an
electric instantaneous water heater can only supply a maximum of 1.06
gallons per minute (gpm) (4.01 liters per minute [L/min]) of water at a
77 deg.F (42.8 deg.C) temperature rise (from 58 deg.F to 135 deg.F
[14.4 deg.C to 57.2 deg.C]) on a continuous draw basis. DOE believes
this is far below the requirements of a whole-house application which
could range from 3-5 gallons per minute. Furthermore, the limit on the
input heating rate of electric instantaneous water heaters is not
likely to change because it is limited by the current carrying capacity
of wiring in most residential housing.
Additionally, DOE believes that the variation of the energy
efficiency of electric instantaneous water heaters would be small for
similar sized models, provided they are tested under similar conditions
because energy losses only occur during the warm-up and cool-down of
the heaters between water draws. However, test data are needed to
determine the magnitude of these losses, which are functions of the
water used during each draw and the frequency of draws. No field data
is available on the average draw rate, amount per draw, and the average
daily draw volumes for these small electric, point-of-use type
instantaneous water heaters. The daily hot water usage of 64.3 gal
(243.4 L) specified for whole-house application does not apply to these
small heating capacity electric units. Consequently, the energy
efficiency, and energy consumption cannot be determined for these units
without additional data. Therefore, DOE will not test electric
instantaneous water heaters for energy efficiency or energy consumption
until a future rulemaking when the daily hot
[[Page 25998]]
water usage data for point-of-use instantaneous water heaters are
available.
DOE did not receive any indication until after the October 1997
notice of reopening that residential oil-fired instantaneous water
heaters are on the market. DOE's belief that these water heaters were
not being sold in the United States was supported by GAMA, Bock, EEI,
the FTC, and the Oregon Energy Office. DOE believes that there is not
time for adequate public review and comment to include oil-fired
instantaneous water heaters in this rulemaking. Accordingly, DOE
withdraws its proposal to test oil-fired instantaneous water heaters in
today's Final Rule.
The Department will continue to require the testing of gas-fired
instantaneous water heaters for energy efficiency and energy
consumption because data is needed for the FTC labeling program.
b. GPM v. First-Hour Rating. In the 1995 proposed rulemaking, DOE
proposed testing for electric and oil-fired instantaneous water heaters
based on the first-hour rating currently used for gas-fired
instantaneous water heaters. This proposal would test instantaneous
water heaters in a manner equal to gas-fired storage-type water
heaters. On October 31, 1997, DOE reopened the comment period on first-
hour rating for instantaneous water heaters. In its reopening notice,
DOE proposed to revise the first-hour rating for instantaneous water
heaters from gallons per hour to a test that measures the maximum flow
rate in gallons per minute (gpm) (liters per minute [L/min]) at a
77 deg.F (42.8 deg.C) temperature rise. DOE proposed to call this
rating the maximum gpm rating.
DOE's proposed revision was in response to concerns raised by
several commenters regarding the March 1995 proposed rule. EEI, EPRI
and the Tennessee Valley Authority (TVA) considered the proposed first-
hour rating procedure for instantaneous water heaters to be
inappropriate because it would lead consumers to ``mistakenly compare
instantaneous and storage-type water heaters as being equivalent.''
They argued that a storage-type water heater can supply a large amount
of hot water during a short draw period, whereas an instantaneous water
heater may not be able to supply a similar amount of hot water because
it is limited by its heating rate. (EEI, No. 2 at 5, No. 27 at 5, and
July 12-13, 1995, Public Hearing Transcript [hereafter referred to as
July 1995 Transcript] at 22 and 27; EPRI, No. 17 at 4; and TVA, No. 14
at 2.)
During the 1997 workshop and in its written comments, EPRI
recommended a rating based on the maximum gpm flow rate at a 50 deg.F
(27.8 deg.C) temperature rise if a single rating value is used, and at
both a 50 deg.F and 77 deg.F temperature rise if two rating values are
used. EPRI stated that it prefers a rating at both a 50 deg.F and
77 deg.F temperature rise. (EPRI, No. 56 at 11.)
GAMA supported EPRI's alternative of a maximum flow rate. However,
GAMA's alternative test procedure involves adjusting the flow rate to
obtain a temperature rise of 77 deg.F in the instantaneous water
heater, and using this maximum gpm flow rate as the rating
characteristic, rather than the current first-hour rating value. GAMA
recommended that the temperature rise be the same as specified for
storage-type water heaters--that is, 77 deg.F, not 50 deg.F as
suggested by other commenters. (GAMA, No. 35 at 2.) GAMA stated it
selected a temperature rise of 77 deg.F because hot water also will be
used for machine-related applications (dishwashers and clothes washers)
that require a 135 deg.F (57.2 deg.C) temperature. (GAMA, February 1997
Transcript at 127 and 138.)
Virginia Power supports the proposal to rate instantaneous water
heaters with a maximum gpm rating. (Virginia Power, No. 42 at 2 and No.
66 at 2-3.) However, Virginia Power supports dual maximum gpm ratings,
at both 50-52 deg.F and 77 deg.F rise. Virginia Power stated that both
temperature rises are used in applications (human-contact at 110 deg.F
[43.3 deg.C] and machine use at 135 deg.F [57.2 deg.C]. Virginia
further stated that DOE's statement in the October 1997 reopening
notice that a 77 deg.F temperature rise will ensure that consumers in
cold regions of the country will have an acceptable water temperature
is inconsistent with the rationale used to establish other parameters
of the test procedure (i.e., establishing on the basis of national
average values). (Virginia Power, No. 50 at 2 and No. 66 at 3.) EEI
supported Virginia's position on this issue. (EEI, No. 65 at 1.) Oregon
stated that both a 50 deg.F and 77 deg.F would be useful in sizing a
unit properly. (Oregon, No. 51 at 3.) State Industry claimed that a
rating value based on a nominal temperature rise of 50 deg.F would not
provide consumers with information on whether the heater is capable of
delivering hot water at a 77 deg.F temperature rise. (State Industry,
February 1997 Transcript at 134.)
Based on the comments, DOE believes there is a consensus that the
current first-hour rating for instantaneous water heaters may mislead
consumers because it may overstate the capability of the instantaneous
water heater to provide a given quantity of hot water at a given
instant of time. The suggestion from GAMA, EEI, EPRI, and other
commenters to replace the first-hour rating parameter with a maximum
flow rate (gpm) over a specific temperature rise (77 deg.F [42.8 deg.C]
or 50 deg.F [27.8 deg.C]) instead of a total volume flow over one hour
is reasonable. This comparison measures the ability of instantaneous
water heaters to deliver the maximum possible amount of hot water to
the user at a specific temperature rise occurring any single moment.
Because some consumer appliances require a hot water temperature in the
135-140 deg.F (57.2-60 deg.C) range, information on the amount of flow
at a 77 deg.F rise is needed. Also, a rating value based on a nominal
temperature rise of 50 deg.F would not provide consumers with
information on whether the heater is capable of delivering hot water at
135 deg.F. Therefore, DOE believes that the maximum flow rate at the
rated energy input rate and at a temperature rise of 77 deg.F across
the water heater should be specified for rating the capability of
instantaneous water heaters to deliver hot water. Furthermore, this
maximum flow rate should be specified in place of the first-hour
rating. The Department is therefore creating a new rating for
instantaneous gas and electric water heaters using a ``maximum gpm draw
rate at 77 deg.F rise'' criterion, and renaming the criterion from
``First-Hour Rating'' to ``Maximum GPM Draw Rating'' in Sections 5.2
and 6.2 of today's Final Rule.
c. Water Temperature Rise. Regarding the outlet water temperature
for gas-fired instantaneous water heaters, the Controlled Energy
Corporation (CEC) submitted a written statement to DOE and distributed
the statement at the February 1997 workshop. CEC stated that the outlet
water temperature for an instantaneous water heater should be at 110-
115 deg.F because there is no practical domestic use for water at
135 deg.F. (CEC, February 1997 Transcript at Appendix H at 4 and No. 63
at 3.) Additionally, CEC claimed the 135 deg.F temperature specified
for storage-type water heaters is simply to increase the heat content
of the stored water and therefore is not relevant for instantaneous
water heaters. (CEC, February 1997 Transcript at Appendix H at 4.)
Group Thermo suggested that a 50 deg.F temperature rise is too low
for some cold regions of the country, and Bock suggested it is too low
for certain well water sources. EEI supported a temperature rise of
50 deg.F because there are many places like Miami and Texas with high
ground water temperatures for
[[Page 25999]]
most, if not all, of the year. EPRI supported a 50 deg.F temperature
rise because that is representative of typical human usage and a rise
of 77 deg.F because that is typical of machine usage. A.O. Smith
favored a single rating at a 77 deg.F temperature rise because it is
simpler and allows comparisons with storage-type water heaters. (Group
Thermo, February 1997 Transcript at 133 and 138; Bock, February 1997
Transcript at 132; EEI, February 1997 Transcript at 136; A.O. Smith,
February 1997 Transcript at 141; and EPRI, No. 56 at 11.)
The Department will continue to specify the test conditions for
water heater temperatures at 58 deg.F inlet (Title 10 CFR, Part 430,
Subpart B, Appendix E, Section 2.3) with a 77 deg.F rise to address (1)
machine-use applications that require a 135 deg.F water temperature for
efficient operation, and (2) the performance of a water heater in
regions of the country that may have a significantly lower supply
(inlet) temperature. Additionally, a single value of 77 deg.F rise will
reduce the test burden on manufacturers.
d. Draw Schedule. DOE did not propose any changes in the draw
schedule for instantaneous water heaters. There were several comments
addressing this issue. During the 1997 workshop, EPRI commented that
for large, whole-house, fossil-fueled instantaneous water heaters, the
losses due to warm-up and cool-down after each water draw become
significant because of the thermal mass of the water and the heat
exchanger. Also, EPRI stated the number of draws (six) in the existing
test procedure for energy factor (EF) tests is not high enough to
account for the daily total cyclical loss that occurs in practice. EPRI
claimed that in the field there are 20-50 draws per day. EPRI suggested
that tests be conducted on smaller tank types and whole-house
instantaneous water heaters to compare the difference in losses caused
by a larger number of draws throughout the day. (EPRI, February 1997
Transcript at 166, 173, and 178.)
In its written statement, CEC also requested that the draw schedule
in the 24-hour simulated use test for modulating gas-fired
instantaneous water heaters be changed from an equal number of draws at
the maximum and minimum firing rates (three at each) to 75% of the
draws at the maximum firing rate and 25% at the minimum firing rate.
CEC stated that this would reflect the fact that most of the daily hot
water consumption is at the maximum firing rate, which, CEC stated, is
when the efficiency of its heater is highest. CEC stated that the
minimum firing rate is provided for the convenience of consumers for
hand washing, etc. (CEC, February 1997 Transcript at Appendix H at 3
and No. 63 at 2.)
DOE recognizes that the number of draws will affect the energy
factor and the annual energy consumption of instantaneous water
heaters. The reason is that the warm-up and cool-down of the heat
exchanger between hot water draws will reduce the measured average
outlet temperature from the specified nominal 135 deg.F resulting in a
lower energy factor and a higher energy consumption when the outlet
temperature is adjusted back to the nominal temperature in the
calculation procedure. The decrease in outlet temperature is
proportional to the number of draws under a constant total daily draw
volume. However, DOE has no data on the amount of daily hot water usage
at the minimum or maximum firing rate for modulating gas-fired
instantaneous water heaters. Hence, there is no basis for DOE to change
the number of draws for instantaneous water heaters at either a fixed
firing rate or for modulating instantaneous water heaters at the
minimum or maximum firing rate in the 24-hour simulated use test.
Additionally, DOE needs data to substantiate any change to the number
of draws during the 24-hour simulated use test for instantaneous water
heaters because changing the number of draws is likely to reduce the
energy factor for existing units thereby requiring a modification to
the energy conservation standard for those products.
e. Energy Factor Measurement. DOE proposed a 24-hour simulated use
test for instantaneous water heaters that is exactly the same as the
24-hour simulated use test for storage-type water heaters. The 24-hour
simulated use test would determine the amount of fuel or electricity
used during a 24-hour period to heat 64.3 gallons of water to 135 deg.F
with the water being drawn in six equal draws at one-hour intervals.
Also, if the instantaneous water heater allows variable input rates,
the fuel or electricity consumed to heat 64.3 gallons of water to
135 deg.F during a 24-hour period would be determined with three draws
at the maximum flow rate and three draws at the minimum flow rate. In
the current test procedure, the recovery efficiency is calculated from
the output energy of the first draw (determined from water mass,
temperature, and specific heat) divided by the measured input energy
used during the first draw of the 24-hour simulated use test for units
with a single firing rate. For modulated units, the recovery efficiency
is the average of the two recovery efficiencies calculated on the basis
of data from the first draw (at the maximum input rate) and the fourth
draw (at the minimum input rate) of the 24-hour simulated use test.
In its comments to the 1995 proposed rulemaking, Paloma Industries,
Inc., suggested that for gas-fired instantaneous water heaters, two EF
values should be determined in the test procedure. These values would
reflect test conditions with (1) the pilot light being continuously on,
and (2) the pilot light being off except when hot water is needed. The
pilot-light-on condition is the case in which the pilot light is always
on regardless of whether there is a demand for hot water. The second
test condition is for the case in which a consumer turns the pilot
light off when hot water is not needed. Paloma claims that with its
Piezo-Elecric Ignition and Subsidiary Pilot Burner Assembly, the
consumer can manually light the pilot easily (in about 10 seconds time)
when hot water is needed. CEC concurred with Paloma. (Paloma
Industries, No. 7 at 3; CEC, February 1997 Transcript at Appendix H at
4 and No. 63 at 2.) Furthermore, CEC stated that differentiating water
heaters with pilot lights from those without is even more important
because CEC will introduce a unit in 1998 with electronic ignition.
(CEC, No. 63 at 2.)
With respect to the issue of the pilot light status between hot
water draws, GAMA recognized that turning off the pilot will reduce
energy consumption and increase the energy factor. GAMA also stated
that turning off the pilot light may not be practical for a whole-house
application. Bock expressed the same opinion. Oregon suggested that it
is possible to have two energy factors, one based on the pilot light on
between draws and one based on it being off. Oregon also recommended
that a test procedure for instantaneous water heaters should account
for warm-up, cool-down and pilot light losses. (GAMA, February 1997
Transcript at 170 and 176; Bock, February 1997 Transcript at 171;
Oregon, No. 51 at 3.)
DOE believes the suggestion to compute two energy factors is valid
only if the consumer can conveniently turn the pilot light off and on
automatically at the point of use (e.g., at the faucet or showerhead)
and if no other faucet or appliance requiring hot water is connected to
the same water heater. Neither Paolma nor CEC indicated that such an
approach was possible with their equipment although CEC has stated that
it will introduce a model with electronic ignition in 1998. DOE
believes that manual shut-off for pilot lights on instantaneous water
heaters
[[Page 26000]]
would not be practical for widespread use and energy savings.
Therefore, DOE will continue to calculate one energy factor.
2. Storage-type Water Heaters With Rated Storage Capacities Less Than
20 Gallons
In the 1995 proposed rulemaking, DOE proposed to cover storage-type
water heaters with rated storage capacitites less than 20 gallons (76
liters). This proposal was in response to a July 17, 1991, letter from
GAMA that stated that storage-type water heaters less than 20 gallons
(76 liters) are not covered by the existing test procedure.
To cover these water heaters, DOE proposed to adopt the draw rate
and the schedules in ANSI/ASHRAE Standard 118.2-1993, ``Method of
Testing for Rating Residential Water Heaters,'' to be used in the
first-hour rating test and the 24-hour simulated use test. The draw
schedules are as follows: (1) For units with rated storage less than 10
gallons (38 liters), a total volume of 9 gallons (34 liters) shall be
withdrawn, and (2) for units with rated storage greater than or equal
to 10 gallons (38 liters) but less than 20 gallons (76 liters), a total
volume of 24 gallons (91 liters) shall be withdrawn. The draw rate for
both draw schedules shall be 1.0 gallon 0.25 gallons per
minute (3.8 liters 0.95 liters per minute). DOE also requested
comments and data on its proposal to extend test procedure coverage to
storage-type water heaters of less than 20 gallons (76 liters).
Several commenters objected to one or more of these proposals.
These commenters variously cited the following reasons: (1) The
existing minimum efficiency standards are based on field applications
and usage requirements for larger volume water heaters and are
inappropriate for smaller-volume water heaters, for example, fitting
and connection losses would be unfairly treated for smaller-volume
water heaters because those losses would represent a larger percentage
of total losses; (2) it is difficult to install thermocouples and to
control flow rates in smaller-volume water heaters; (3) smaller-volume
water heaters cannot meet the efficiency requirement because they
typically are installed in confined areas, which limits the amount of
insulation used to reduce surface losses; and (4) a flow rate of 1 gpm
during water draws is too large for smaller water heaters' it would
quickly deplete the quantity of hot water in tanks of 2.5 gallons or
less. (GAMA, No. 1 at 3, No. 35 at 3, and July 1995 Transcript at 12;
EPRI, No. 17 at 2; EEI, No. 2 at 6, No. 27 at 5, and July 1995
Transcript at 28; Oregon, No. 51 at 3 and February 1997 Transcript at
164 and 195; TVA, No. 14 at 1; The Southern Company Services, Inc., No.
24 at 2; American Electric Power, No. 38 at 1; Potomac Electric Power,
No. 26 at 3; CSW, No. 4 at 2; Centerion Energy, No. 22 at 1; Nevada
Electric Power, No. 45 at 2; National Rural Electric Cooperative
Association, No. 18 at 2; Decatur County REMC, No. 19 at 1; and Dayton
Power and Light, No. 20 at 1.)
GAMA suggested that separate piping arrangement figures be used for
floor-mounted models of less than 20 gallons storage capacity. GAMA
provided the schematic drawings for its suggested changes. (GAMA, No. 1
at 6 and July 1995 Transcript 17.)
Vaughn Manufacturing Corporation claimed: (1) The number of units
is a small percentage of the total; (2) this is a utilitarian product
which is used to fit special circumstances when other alternatives are
not available; and (3) the publication of energy factors will not cause
the purchaser to choose a more efficient model to an extent that will
make a significant difference in national energy conservation. (Vaughn,
No. 31 at 2.)
However, AGA believed that the large number of such heaters sold
justifies some measurement that could be used for a minimum standard.
(AGA, February 1997 Transcript at 184-185.) GAMA proposed running only
a stand-by loss test for the measurement, and EPRI proposed to base
this measurement on the maximum stand-by loss without considering daily
water consumption. GAMA argued that any standard would have to be
connected to some level of daily consumption. The FTC pointed out that
if the test procedure covers these products, they would have to be
labeled, and the label has to contain a value for energy consumption.
In its written comments, GAMA stated that the applicable maximum hourly
stand-by loss requirement in ASHRAE 90A-1980 was 43W. GAMA asserted
that because the ASHRAE loss was based on an 80 deg.F temperature
difference, the DOE maximum loss rate should be 36.3W, based on the
67.5 deg.F temperature difference for the DOE test. GAMA concluded that
the DOE proposal for the 24-hour simulated use test should be scrapped
and that only an hourly stand-by loss should be measured by the test
procedure. (GAMA, No. 35 at 4 and February 1997 Transcript at 165 and
185-186; EPRI, February 1997 Transcript at 183-184; and FTC, February
1997 Transcript at 186.) This proposal was not supported by Virginia
Power, who claimed that losses for fittings were greater for small
tanks and that specialized uses for these tanks may limit the kinds of
modifications leading to improved efficiency. Oregon supported the
stand-by loss proposal and added that heaters with capacity equal to or
less than 2 gallons (7.6 liters) be exempt from coverage and that all
water heaters less than 20 gallons (76 liters) be exempt from the
Energy Guide labeling requirement. EPRI expressed general support for
GAMA's proposal, but suggested that a combination of stand-by loss and
recovery efficiency rather than a single energy efficiency term be used
to determine the energy standard for small water heaters. (Virginia
Power, No. 42 at 3; Oregon, No. 51 at 3 and February 1997 Transcript at
164 and 195; EPRI, No. 56 at 5 and February 1997 Transcript at 164,
183, and 188 and at Appendix J at 2.)
Although the Department believes the stand-by loss measurement for
water heaters less than 20 gallons (76 liters) proposed by GAMA and
EPRI may be feasible, DOE will reserve consideration of this proposal
for a future revision of the test procedure. The reasons for this
decision are: (1) Absence of data to determine the appropriate daily
hot water consumption, and (2) DOE's need to develop and evaluate the
stand-by loss procedure. Therefore, DOE is withdrawing its proposal in
today's Final Rule.
3. Definitions
In the 1995 proposed rule making, DOE solicited comments on the
addition to the test procedure of definitions of a heat pump water
heater storage tank and a solar water heater. DOE also proposed to
revise the definition of a heat pump water heater to specify two types,
an integral heat pump water heater and an add-on heat pump water
heater.
The following discussion ensued:
(i) Solar Water Heater. GAMA stated that it did not understand the
purpose or intent of the expanded definitions or the need to define
``solar water heaters'' for the test procedure. GAMA suggested that the
requirement that a solar water heater obtain 50% of its annual heating
energy from the sun is not a definitive criterion because a solar water
heater with less than 50% of its input energy from the sun is still a
solar water heater. (GAMA, July 1995 Transcript at 15 and No. 1 at 5.)
(ii) Heat Pump Water Heater Storage Tank. During the February 1997
workshop, GAMA proposed that a 50-gallon tank standardized with respect
to the energy factor is adequate and should be used to test any add-on
heat pump water heater sold without a tank by its manufacturer. (The
existing DOE test
[[Page 26001]]
procedure specifies a 47-gallon tank meeting the minimum standard
energy factor or not greater than .02 EF above the minimum.) GAMA
objected to the Department's proposal for a special heat pump water
heater storage tank.
EPRI objected to the inclusion of a special heat pump water heater
storage tank, and proposed that an add-on heat pump water heater be
tested with a standard 50-gallon tank as required under the existing
DOE test procedure. EPRI further stated that there are no storage tanks
labeled and designed for use exclusively with heat pump water heaters.
All other commenters, such as the Oregon Energy Office and Virginia
Power, agreed with GAMA's and EPRI's proposals for a standard 50-gallon
tank. The Oregon Energy Office called for a revision of the original
definition. (GAMA, February 1997 Transcript at 229; EPRI, No. 17 at 5
and February 1997 Transcript at 227; Oregon, No. 51 at 6; Virginia
Power, No. 50 at 4.)
(iii) Add-on Heat Pump Water Heaters. EEI expressed concerns about
the definition of add-on heat pump water heaters. EEI and EPRI claimed
the definition is inappropriate and should not be adopted. They stated
that add-on heat pump water heaters are designed to work with any
electric water heater tank and that some are designed to work with any
tank. EPRI claimed the new definition limits the availability of tanks
for use with add-on heat pump water heaters. EPRI believes that this
new definition would increase the cost. Further, EEI found that this
definition is ill-advised, because new tanks of essentially identical
construction must meet two definitions, thus creating confusion and
potentially increasing the cost of heat pump water heaters. (EEI, No. 2
at 7, and No. 27 at 7; EPRI, No. 17 at 5.)
Virginia Power proposed deleting ``heat pump'' from the last line
of the definition. (Virginia Power, No. 50 at 4.)
Vaughn Manufacturing Corp. commented that the addition of more than
one category of heat pump water heaters, or even solar water heaters,
will add to the confusion because it may lead consumers to compare test
results of dissimilar types of water heaters. (Vaughn, No. 31 at 4.)
(iv) Integral Heat Pump Water Heaters. GAMA suggested that, instead
of the 1995 DOE proposed definitions of ``integral heat pump water
heaters'' and ``add-on heat pump water heaters,'' the respective
definitions should be ``heat pump water heaters with tanks'' and ``heat
pump water heaters without tanks''.
Also, GAMA objected to the term ``integral heat pump water
heaters'' because it implies that the heat pump is structurally
integrated with a tank, whereas in reality, the heat pump and the tank
can be physically separated, but are usually sold by the manufacturer
as a packaged unit. (GAMA, February 1997 Transcript at 230.)
Virginia Power proposed deleting the definition of ``integral heat
pump water heater.'' (Virginia Power, No. 50 at 4.)
(v) Proposed Revisions. DOE responded to these comments in the
October 1997 reopening notice. In this notice, DOE proposed the
following revisions:
Withdraw the definition of solar water heaters.
Withdraw the proposal for heat pump water heater storage
tanks for testing with an add-on heat pump water heater.
Delete the definition of integral heat pump water heaters.
Replace the definition of ``integral heat pump water
heaters'' with the definition, ``Heat pump water heater with storage
tank means an air-to-water heat pump sold by the manufacturer with an
insulated storage tank as a packaged unit. The tank may be integral
with or separated from the heat pump.''
Replace the definition of ``add-on heat pump water
heater'' with the definition, ``Heat pump water heater without storage
tank (also called add-on heat pump water heater) means an air-to-water
heat pump designed for use with a storage-type water heater or with a
storage tank that is not specified or supplied by the manufacturer.''
EEI, Virginia Power, and GAMA supported DOE's proposed definitional
changes in the October 1997 notice of reopening. (EEI, No. 65 at 1;
Virginia Power, No. 66 at 4; and GAMA, No. 67 at 1.) No commenter took
issue with the proposed definitional changes.
Therefore, DOE is adopting in this Final Rule the proposed revision
as stated above.
4. Heat Pump Water Heaters
a. Back-up Electric Resistance Heating. In the Proposed Rule, the
Department requested comments on the adequacy of the existing test
procedure regarding back-up electric heating elements for heat pump
water heaters because the current test setup and parameters may not
represent operating conditions requiring the resistance element(s) to
be activated. The existing procedure does not account for energy used
by these elements because most heat pump water heaters are capable of
meeting the test draw requirements of the 24-hour simulated use test
for the energy factor and, therefore, the back-up electric resistance
heating element(s) is not activated.
GAMA stated that the current draw schedule is such that the back-up
electric resistance element(s) does not turn on during testing.
Although GAMA concluded from tests conducted at Intertek Testing
Service (ITS) that changing the current draw schedule by increasing the
volume of water withdrawn will not activate the elements, it still
argued that in residential applications, a significant percentage of
the energy for water heating (15-20%) comes from the back-up resistance
element(s). GAMA asserted that this energy should be included in
determining the annual energy consumption of the heat pump water
heater. This view is shared by the Southern Company Services (SCS).
(GAMA, No. 1 at 5, No. 35 at 5, July 1995 Transcript at 16, and
February 1997 Transcript at 241; and SCS, No. 24 at 2.) Vaughn
Manufacturing Corporation claimed that the one-hour recovery between
the six small draws prejudices the test procedure in favor of heat pump
water heaters. Furthermore, Vaughn claimed, this test profile is not
based on a representative average use cycle. (Vaughn, No. 31 at 3.)
Georgia Power recommended that the draw schedule continue to stipulate
10.7 gallons per draw for each hour. (Georgia Power, No. 54 at 2.)
GAMA recommended adding some electrical energy to the annual energy
consumption calculation but GAMA did not recommend a specific amount of
energy. GAMA claimed that this electrical energy was necessary because
no resistance heating was measured during tests of heat pump water
heaters using the DOE test procedure and GAMA claims that it is well
accepted that heat pump water heaters use backup resistance heating
during periods of heavy draws. (GAMA, No. 57 at 2 and February 1997
Transcript at 240-260.) The recommendation was supported by AGA and the
Oregon Energy Office. (AGA, February 1997 Transcript at 254 and 263;
Oregon, February 1997 Transcript at 248, 250, and 255; and Oregon, No.
51 at 5.)
However, EPRI claimed that its data shows that less than 10 percent
of the energy consumption for water heating with heat pumps actually
comes from the back-up resistance elements for customers who use about
64 gallons of hot water per day. EPRI argued that it would be improper
to apply a correction factor to compensate for resistance elements that
do not activate during average test conditions. Moreover, EPRI added
that if a correction factor is applied to heat pump water heaters,
[[Page 26002]]
then correction factors due to regional conditions would need to be
applied to all types of water heaters. Based on these reasons, EPRI is
opposed to the recommendation by GAMA. (EPRI, No. 56 at 2, February
Transcript at 239, 248, 257 and 264 and at Appendix J at 2.) Virginia
Power agreed with EPRI's comments. (Virginia Power, No. 50 at 4, and
February 1997 Transcript at 249 and 258.)
Other opponents to GAMA's recommendation included Abrams and
Associates, who commented that the purpose of the test procedures is to
rate water heaters for comparison purposes rather than to reflect
actual household applications. Lawrence Berkeley National Laboratory
(LBNL) stated that heat pump water heaters do not need a separate test
procedure to account for backup resistance heating because of their
insignificant market share and greater efficiency. EEI commented that
to activate the heating elements would require a draw in excess of 50
gallons, which is not realistic. AIL Research stated that no correction
factor should be used until data becomes available. (Abrams, February
1997 Transcript at 260; LBNL, February 1997 Transcript at 252; EEI,
February 1997 Transcript at 255; and AIL, February 1997 Transcript at
261-264.)
The Department believes that the 24-hour simulated use test for the
energy factor must be based on average test conditions that also apply
to other water heaters of comparable size and use so that all storage-
type water heaters are tested and rated on a consistent and uniform
basis. Furthermore, DOE notes that based on test data submitted by
GAMA, the back-up heating elements for heat pump water heaters will not
activate when the volume of hot water drawn is changed from 10.7
gallons to a more severe 21.4 gallons per draw during two of the six
draws of the 24-hour simulated use test. The Department believes that
any single draw in the draw schedule greater than the 21.4 gallons per
draw (as tested) would not be considered as an average use pattern.
Because the test procedure is for comparison purposes and is not
intended to take into account all potential field use patterns (such as
the draw-down of the storage tank), DOE considers that a revision to
the current draw schedule of 10.7 gallons per draw for the six draws in
the 24-hour simulated use test (for example, stipulating 21.4 gallons
per draw for two of the six draws) is not necessary because it will not
change the result. Furthermore, there is no agreement on an average
percent of the annual energy consumption that comes from the resistance
heating elements. Therefore, the Department concludes that applying a
correction to the energy factor and/or annual energy consumption of the
heat pump water heater to account for the energy used by the resistance
elements that do not activate during testing is unwarranted and will
not be included in today's Final Rule.
b. Installation Requirements. The installation requirements in
Section 4.1 of Appendix E of the current test procedure state that a
heat pump water heater without a manufacturer-supplied storage tank
shall be connected to the storage tank in accordance with the
manufacturer's instructions. The requirements further state, ``If
installation materials are not provided by the heat pump manufacturer,
use uninsulated 8 foot (2.44 m) long connecting hoses, having an inside
diameter of 5/8 inch (1.6 cm).'' The intent of this requirement is to
specify a uniform test setup for those units that do not include
manufacturer's instructions. DOE asked for comments on this issue.
EPRI commented that the term ``installation materials'' in this
context is unclear. EPRI suggested changing ``installation materials''
to a more descriptive term because most manufacturers of add-on heat
pump water heaters, or any other type of water heater, do not provide
the plumbing hardware and should not be penalized for not doing so.
(EPRI, No. 17 attached report at 6.) American Electric Power claimed
that the installation requriements were vague. (American Electric, No.
38 at 1.) Oregon suggested that in cases in which manufacturers do not
include instructions, the test procedure should be performed using
insulated hoses of sufficient length and size to properly mount the
heat pump unit relative to the storage tank. (Oregon, No. 51 at 6.)
To make the wording clear, DOE is revising the text in section 4.1
of Appendix E from ``installation materials'' to ``installation
instructions'' as suggested by EPRI. DOE disagrees with Oregon's
comment because in most residences, the hot water pipes usually are not
insulated. DOE believes that the 8-foot hose is adequate to make the
heat-pump-to-water-heater connection and ensure that the heat loss from
the uninsulated hose is equal for all add-on heat pump water heaters
that do not have manufacturers' installation instructions.
c. Heat from the Ambient Air. The current and proposed test
procedures use the same test conditions and test procedures for oil-
fired, electric and heat pump water heaters. Vaughn claimed that
because the DOE test procedure does not account for heat removed from
the ambient air, the procedure favors heat pump water heaters. (Vaughn,
No. 31 at 3.)
The Department has considered this topic and has concluded that the
interactions between heat pump water heaters and the building
environment are extremely complex and difficult to measure.
Furthermore, in some cases, heat pump water heaters may be installed
outside the building, in which case the heat removed from the ambient
air is free and does not need to be counted. For these reasons, DOE
will address building and heat pump interactions in a future
rulemaking.
5. First-Hour Rating for Storage-type Water Heaters
In the 1995 proposed rulemaking, DOE proposed a revised test
procedure for the first-hour rating for storage-type water heaters. The
proposed revision specifies the start of a first draw at the beginning
of the one-hour period, when the average tank temperature is at the
specified limit of 135 deg.F 5 deg.F (57.2 deg.C
2.8 deg.C) and all the thermostats are satisfied. The
first draw is terminated when the outlet water temperature decreases by
25 deg.F (13.9 deg.C) below the maximum outlet temperature recorded
during the draw. Successive draws are initiated when the uppermost
thermostat is satisfied following a tank recovery, and ended when the
outlet water temperature decreases by 25 deg.F (13.9 deg.C) below the
maximum outlet temperature recorded during each particular draw.
At the end of the one-hour period, a final draw is initiated if no
draw is in progress. This draw is terminated when the outlet water
temperature decreases to the value used to terminate the draw that was
completed before this final draw. If a draw is in progress at the end
of the one-hour period, this draw is continued until the outlet water
temperature decreases by 25 deg.F (13.9 deg.C) below the maximum outlet
temperature recorded during this draw. A temperature correction factor
is applied to the last draw. The correction factor is a quotient in
which the numerator is the average delivered water temperature of the
last draw minus the minimum water temperature of the next-to-last draw
and the denominator is the average delivered water temperature of the
next-to-last draw minus the minimum water temperature of the next-to-
last draw. The correction factor corrects for any significant reduction
in energy content of the draw due to a lower average outlet water
temperature over the draw
[[Page 26003]]
than those obtained during the earlier draws.
Thermally compensating dip tubes and integral mixing valves result
in higher first-hour ratings. DOE did not propose to apply a correction
factor to water heaters employing these features because the Department
was unaware of the existence of these features on currently
manufactured water heaters. However, EPRI, EEI, and Nevada Power
Company stated that because at least one U.S. manufacturer has
purchased the right to manufacture and sell the equivalent of an
``internal mixing'' product, DOE should develop a procedure that
accounts for differences in hot water delivery temperatures. (EEI, No.
27 at 5; EPRI, No. 17 at 12; and Nevada Power Company, No. 45 at 3.)
Southern Company Services (SCS) argued that specifications for mixing
valves (similar to internal mixing) are not relevant to efficiency and
the use of mixing valves should not be restricted. Furthermore, SCS
supported the test procedure proposed by Dr. Carl Hiller of EPRI, which
it claimed would not be affected by mixing valves. (SCS, No. 24 at 2.)
EEI and EPRI commented that DOE's proposed first-hour rating
procedure, while an improvement over the current (1991 Final Rule) and
previous (1978) DOE procedures, is still flawed and should not be
implemented. Both EEI and EPRI based their comments on the analysis of
the DOE proposed procedure by Dr. Carl Hiller of EPRI. (EEI, No. 2 at
2, No. 27 at 2, and July 1995 Transcript at 22; and EPRI, No. 17
attached report at 2.)
Dr. Hiller commented that the DOE proposed procedure is based on
unrealistic water consumption behavioral patterns, and bears little
relevance to the sizing of hot water systems. Dr. Hiller stated that
the procedure gives misleadingly high ratings to units having a high
heat input rate, thus penalizing electric systems and systems with
larger tanks. Dr. Hiller suggested that the entire proposed procedure
should be abandoned and replaced with an alternative developed by EPRI.
(EPRI, No. 17 at 9 and 13.)
Specifically, Dr. Hiller claimed that the DOE proposed first-hour
rating procedure for storage-type water heaters is characterized by the
following: (1) It penalizes large tanks because the draw rate of 3 gpm
causes the draws to take longer for larger tanks, thus limiting useful
reheat time; (2) the temperature correction factor applied to the last
draw is cumbersome; (3) the draw at the end of the one-hour test
results in a variable test time; (4) depending on the thermostat
setting and behavior, two similar tanks may show dramatic differences
in their first-hour ratings; (5) the one-hour time period in the
procedure is arbitrary and relatively irrelevant to water heating
system sizing; and (6) the procedure fails to account for the energy
content of water delivered at different temperatures during the draws.
(EPRI, No. 17 at 9-13.)
Dr. Hiller proposed three EPRI alternatives to DOE's first-hour
rating procedure. The first alternative calculates first-hour rating as
the sum of (1) the volume of water from an initial draw (multiplied by
a factor to correct to a uniform delivery temperature of 110 deg.F
(43.3 deg.C) and (2) the maximum useful reheat volume (water is heated
to 110 deg.F [43.3 deg.C]) at the rated energy input between the end of
the first recovery (after the first draw) and the end of a specified
reheat time period. This EPRI proposal uses a calculation to determine
the maximum useful reheat volume during the specific reheat period;
EPRI notes that the maximum useful reheat volume could also be
determined with actual draws. In this proposal, EPRI advocates a reheat
period of 35-45 minutes instead of one hour. (EPRI, No. 17 at 13.)
The second EPRI alternative, proposed by Dr. Hiller at the February
1997 workshop, bases tank sizing on a graph of the way hot water is
actually used over a specific time period together with graphical
representations of hot water delivery capability (a stepwise function
versus time due to reheat delay) for various water heaters. The water
heater size is found by overlaying the two graphs of hot water delivery
capability and hot water consumption requirement. EPRI provided
examples of data for several tank sizes for hot water delivered not
exceeding once per day, once per week and once per month derived from a
2\1/2\ year EPRI field study at 14 metered sites with electric storage-
type water heaters. (EPRI, No. 56 at 6, and February 1997 Transcript at
Appendix J at 4-10.)
In its comments after the February 1997 workshop, EPRI proposed a
third alternative first-hour rating procedure, which modified its first
proposal. In this procedure, hot water is drawn initially and during
four reheat cycles. Data from the five corresponding draws (stepwise in
form as in the second alternative) are used to establish a graphical
representation of hot water availability versus time, including the
reheat time delay between the first draw after recovery (on the basis
of the cut-out of the uppermost thermostat) and the subsequent draw.
From these measurements, the actual first draw volume available and the
actual average reheat rate of the system are determined. After the
first reheat is completed, a linear calculation is performed to
estimate the number of additional gallons that can be produced based on
the average reheat rate. Then the ``minimum'' maximum water
availability curve is calculated. The hot water delivery rating from
the graph is determined based on the minimum hot water availability
curve together with a ``critical design time interval'' of 35 minutes.
EPRI claimed that this procedure accounts for the first draw volume and
the reheat rate, as well as the reheat time delay between the hot water
run-out after the first draw and the completion of the recovery (on the
basis of the cut-out of the uppermost thermostat). EPRI claimed that
this procedure is better than the DOE proposed procedure because the
reheat delay time is accounted for. The third alternative differs from
the first alternative primarily because the third alternative involves
four cycles of reheating, and the water temperature at the top of the
tank after recovery is at 135 deg.F (57.2 deg.C) instead of 110 deg.F
(43.3 deg.C). (EPRI, No. 56 attached report at 11-12.)
This proposal includes an optional method that permits
manufacturers to list the first draw as the first draw rating because
the 35-minute hot water delivery rating is typically at or near the
first draw capability of the tank. This avoids the need to perform the
four reheats and five draws. (EPRI, No. 56 attached report at 13.)
Virginia Power and American Electric Power (AEP) also stated their
opposition to the DOE first-hour rating and their support of a maximum
first draw rating. Virginia Power claimed that the maximum first draw
rating more accurately represents typical consumer action. (Virginia
Power, No. 50 at 2; AEP, No. 53 at 1.)
Rheem Manufacturing claimed the first-hour rating is seldom used by
consumers in purchasing water heaters. (Rheem, February 1997 Transcript
at 154-155.)
Georgia Power claimed that the first-hour rating is biased toward
gas-fired water heaters. Georgia Power proposed an alternative method
which involves checking the temperature in the top of the tank
periodically after the first draw is complete. When the temperature is
above the minimum setpoint temperature, a second draw should begin. It
claimed that this procedure reflects the way a consumer would use hot
water after a run-out. (Georgia Power, No. 54 at 1.)
GAMA stated that it does not support EPRI's alternative first-hour
rating
[[Page 26004]]
procedures. GAMA claimed that the current and proposed DOE test
procedure, in which water is drawn from a tank full of heated water and
then subsequent draws are made each time the tank returns to the
setpoint temperature within an hour, is an appropriate way to evaluate
a water heater's capability to provide heated water. GAMA stated that
the DOE procedure may require some modifications and corrections in the
calculations, but GAMA did not believe it is necessary to rewrite the
entire first-hour rating procedure (as suggested by EPRI). (GAMA, No. 1
at 2, and No. 35 at 2, and July 1995 Transcript at 10.)
GAMA claimed the 1990 procedure gives a first-hour rating volume
that may be smaller than the first draw volume for larger tanks. GAMA
presented the results of tests conducted by its water heater
manufacturer members that compared representative models of gas-fired
and electric water heaters. The test results were compiled from both
the current test procedure and the 1995 DOE proposed first-hour rating
test procedure. The data show that the proposed procedure does provide
a first-hour rating that reflects a combination of the water heater's
storage capacity and recovery rate. In a written submittal at the
February 1997 workshop, GAMA presented additional test results
conducted by Intertek Testing Service on water heaters tested in the
GAMA efficiency certification program. The data showed that 53 gas-
fired water heaters (with storage capacities of 30-50 gallons) were
tested, and the difference between the first-hour rating using the
proposed procedure and the first-hour rating based on the current
procedure varied from -0.2 gallons to 8.0 gallons with a standard
deviation for each tank volume class tested of 3.7-6.0 gallons. The
data also showed that 51 electric water heaters (with storage
capacities of 30-82 gallons) were tested, and the differences in rating
value were from 3.7 gallons to 5.5 gallons with a standard deviation
for each tank volume class tested of 2.0-5.8 gallons. GAMA believed
that the data is indicative of a general trend and that it does support
the use of the proposed first-hour rating test procedure. (GAMA, No. 1
at 2, No. 35 at 2, and February 1997 Transcript at 91-92 and at
Appendix I at 1-2.)
GAMA, in the same written submittal at the February 1997 workshop,
claimed DOE should provide an alternative conservative calculation for
the first-hour rating. GAMA's suggested calculations are based on 1995
and 1996 data from GAMA's efficiency certification program. The 1996
data show that the volume of the first draw compared to the rated
volume is about 0.85 for gas-fired water heaters and 0.78-0.85 for
electric water heaters. GAMA proposed three calculations for first-hour
rating: (1) For gas-fired water heaters, the first-hour rating equals
0.8 of the tank volume plus an energy-based correction factor; (2) for
dual-element electric water heaters, the first-hour rating equals 0.75
of the tank volume plus an energy-based correction factor; and (3) for
a single element electric water heater, the first-hour rating equals
0.75 of the volume. GAMA claimed these calculations give conservative
results. (GAMA, February 1997 Transcript at Appendix I at 1-2.)
GAMA, in a later submittal following the February 1997 workshop,
stated that its proposed optional first-hour calculation for electric
water heaters should be modified to provide a more accurate first-hour
value for larger volume models. It stated that the original calculation
leads to an assumption that no recovery will occur for 24 minutes with
an 80-gallon tank. GAMA stated that because the lower heating element
turns on in 2-5 minutes into the first-hour rating test in all electric
water heaters, GAMA decided to modify the volume-related correction
factor for dual-element electric water heaters to reflect this. (GAMA,
No. 57 at 1.)
Supporters of the DOE proposal for determining the first-hour
rating include the AGA, which finds it useful in determining the proper
size of a water heater, stating that proper sizing is important for
energy conservation, customer satisfaction and safety. (AGA, No. 55 at
1.) The Oregon Energy Office recommended DOE adopt its 1995 proposal
and not adopt any part of the EPRI proposals because Oregon claimed
EPRI put too much weight on the first draw volume, thus promoting
larger tanks. (Oregon Energy Office, No. 51 at 2 and February 1997
Transcript at 110-112.) In a statement submitted after the February
1997 workshop, Battelle Columbus presented some experimental data and
analysis of a 35,500 Btu/h, 50-gallon gas-fired water heater. Battelle
presented data to show that the test water heater was able to satisfy
the ``once a month'' draw schedules based on the EPRI field tests of 15
actual households. Battelle claimed that the test water heater could
meet 12 of the 15 household hot water loads with a delivery temperature
above 110 deg.F. Battelle claimed the data showed that the DOE first-
hour rating procedure is a good predictor of water heater performance.
(Battelle, No. 58 at 1.)
George Kusterer of Bock Water Heaters stated that the information
relating to EPRI's alternate first-hour rating method is inconclusive
and recommended it not be accepted by DOE. Bock also claimed that a
first-hour rating based only on the first draw will not work. (Bock,
February 1997 Transcript at 146, 151 and 153.)
In response to EPRI's comments on the effect of the draw rate, DOE
does not agree that a 3 gpm draw rate will result in a shorter reheat
time for larger tanks. This is due to the fact that, for most electric
water heaters, the bottom element will turn on within 5 minutes into
the first draw. Also, a larger draw rate and a longer reheat time may
not increase the total amount of hot water drawn because the heat input
rate and not the draw rate will determine whether a tank can recover to
a minimum temperature of 110 deg.F. This recovery capability is the
reason that the size of the storage tank is not the only criterion for
first-hour rating.
Tank size is critical for simultaneous water usage, but tank
recovery rate, either by a greater input rate or by dual--heating
element design, could prove critical during times of consecutive hot
water usages. While it is true that a consumer will not wait for the
tank water temperature to reach 135 deg.F or the thermostat to cut out
before turning on the hot water faucet, the one-hour rating does
provide a simple and easy to understand indication of the combined
effects of tank size and recovery rate within a reasonable time frame
where heavy use of hot water may occur (for example, during the morning
hours). It is also a definitive procedure for manufacturers to use for
labeling but it is not necessarily an appropriate criterion for tank
sizing since that depends on consumer behavior and uses of hot water.
The temperature correction factor is used to adjust the volume of
the last draw to account for the possible lower heat content of the
last draw than those earlier draws with fully heated water. DOE has
created the temperature correction factor as a simple arithmetic
temperature ratio using temperature data that has already been measured
during the test. DOE realizes that the temperature of the last draw may
be at a lower temperature than those of earlier draws.
DOE does not believe that due to the imposition of the last draw at
the one-hour mark, two similar tanks, one at 111 deg.F and the other at
109 deg.F, will result in a large difference in the amount of total
volume drawn. The temperature correction factor is specifically applied
to prevent that from happening. For example, assuming that the whole
tank of water at 111 deg.F is drawn, the
[[Page 26005]]
temperature ratio, (111-110)/(130-110) = 0.05, will add only 5% of the
last draw volume to the total volume drawn at the one-hour mark. (For
illustration purposes, the maximum outlet temperature is assumed to be
135 deg.F and the average outlet water temperature during a regular--
not the imposed--draw is assumed to be 130 deg.F.) DOE believes this
difference of 5% of the volume of the tank is acceptable for grouping
models of storage-type water heaters.
There were claims that the DOE test period of one hour is too long.
The one-hour time period is related to a similar period of high water
consumption in most residences. Although the EPRI data indicates a
shorter time, DOE believes that more data is necessary to establish a
national average pattern of use, and DOE does not believe that a
reduction of 25 minutes in test time, as suggested by EPRI, is merited.
There were no comments from manufacturers or GAMA that the shorter test
time was desirable. Rather, Darrell Paul, EEI, Bock, and Group Thermo
stated that people tend to adjust their hot water use pattern during
high consumption periods to account for short periods without hot
water. (Battelle Columbus, February 1997 Transcript at 47; EEI,
February 1997 Transcript at 49; Bock, February 1997 Transcript at 52;
Group Thermo, February 1997 Transcript at 53.)
Regarding the comment that a final draw results in a variable
testing time, certainly the imposition of a final draw extends the test
period beyond one hour. However, the procedure requires the cessation
of input energy at the one-hour mark. Therefore, DOE believes this is
an equitable way to account for all the usable heat energy input to the
water heater within the one-hour time frame.
DOE does not believe that a correction factor for hot water tanks
with induced interim mixing will improve the accuracy of the test
procedure enough to warrant its inclusion. DOE does agree that a
temperature correction factor should be applied to the water drawn
during each of the draws if a thermally compensating dip tube or an
internal mixing device is used. However, at the present time there is
no water heater that employs a mixing valve or thermally compensating
dip tube during its normal operation. One design that does employ a
mixing device is a special application for utility demand-side
management in which higher temperature hot water is heated and stored
during periods of low electricity demand. However, such a tank can be
tested under the proposed DOE test. Therefore, a correction factor for
induced internal mixing is not needed at this time.
The Department reviewed and evaluated two of the proposals
presented by EPRI (the second and the third, the latter of which is
EPRI's modification of its first alternative). DOE considers that the
second proposal, as stated by EPRI, is still in the development stage.
DOE believes that when completely developed, the method may be included
and used, in graphical or tabulated forms, in a design manual for use
by designers to size the hot water tank for the needs of a particular
customer. However, to adopt the procedure for a single number rating
purpose would require the development of, and agreement by all
concerned parties to, an average national utilization curve to be used
in conjunction with EPRI's hot water delivery capability graphs for
various models of water heaters. The Department believes that prospect
will not be feasible in the near future. Furthermore, the Department
believes that EPRI's third proposal should not be adopted. The reasons
are (1) the procedure puts more weight on the first draw, which would
tend to encourage the use of larger tanks; (2) the hot water produced
during the recovery period is not included, even though it is available
at the end of recovery; (3) the proposed four reheat cycles may require
a very long test time, especially for larger electric tanks; (4) for
water heaters with a lower heat input rate, the subsequent draw rate,
which provides continuous 135 deg.F (heated up from the 58 deg.F inlet
condition) water and is calculated on the basis of the reheat rate,
will be much lower; and (5) the procedure, and any modification to it,
has not been tested.
The Department has decided not to adopt the optional calculation
procedure proposed by GAMA. The Department checked the optional
calculation procedure against data published in the GAMA directory and
found that the results for first hour rating varied among electric,
gas-and oil-fired water heaters. Furthermore, the coefficients proposed
by GAMA were based on the current test procedure for first hour rating.
The Department believes that the optional calculation may have merit,
but the coefficients need to be based on the first hour rating in this
Final Rule. For these reasons, the Department has decided to adopt the
1995 proposed procedure for first-hour rating in today's Final Rule.
6. Installation of Under-the-Counter and Counter-Top Water Heaters
The installation requirements in section 4 of Appendix E of the
proposed test procedure do not distinguish under-the-counter water
heaters from counter-top water heaters. GAMA recommended these be
addressed separately because they are intended for different
installations. GAMA indicated that because the water connections for
counter-top models are within the water heater jacket, they can be
installed flush to the back wall, and that this is not true for under-
the-counter models. GAMA also recommended that separate piping
arrangements be provided for floor-mounted water heaters with storage
capacities less than 20 gallons. GAMA submitted four figures
illustrating these configurations. (GAMA, July 1995 Transcript at 17
and No. 1 at 6.) Intertek Testing Services confirmed that GAMA's
suggested changes are consistent with the normal practice in testing
these types of models. Intertek further furnished piping schematics for
those under-the-counter models that have a side inlet port and a top
center outlet port. (Intertek, No. 62 at 1.)
The Department supports these proposals. The Department understands
that if a counter-top model is installed with the back surface of the
water heater jacket flush against the wall, the heat loss through the
back surface will be different from an installation in which the back
surface is exposed directly to the ambient air. DOE also understands
that for under-the-counter models, the limitation of space under the
counter necessitates a short piping connection, which should be
reflected in the installation requirement. Therefore, the installation
figures for piping connections for under-the-counter and counter-top
water heaters as provided by GAMA and Intertek are included in today's
Final Rule (as Figures 3, 4, 5, 6, 7A, and 7B in Appendix E). Sections
4.1 and 4.3 of Appendix E are revised to indicate these new figures and
the requirement for a simulated wall against the back side of a
counter-top model.
7. Test Conditions
a. Daily Hot Water Usage. The current test procedure prescribes
water heater testing to determine the energy factor must be based on a
daily hot water usage of 64.3 gallons per day (gpd). DOE did not
propose to change the daily hot water usage in the 1995 proposed
rulemaking.
The American Gas Association (AGA) and Battelle Columbus argued
that the current daily hot water usage is outdated and proposed it be
lowered to 54 gpd to reflect a recent study. (AGA, No. 25 at 2; and
Battelle, No. 46 at 1.) Virginia Power suggested lowering the daily hot
water usage to 50 gpd or less. Virginia Power also stated that because
[[Page 26006]]
the daily usage value is used in energy estimation and design
calculations, changing it to a current value will maximize the
usefulness and applicability of the test results. EEI suggested
lowering the daily hot water usage to 50-57 gpd. Georgia Power argued
for a value close to 50 gpd. (Virginia Power, No. 50 at 3 and February
1997 Transcript at 212 and 223; EEI, February 1997 Transcript at 201;
and Georgia Power, No. 54 at 2.) EPRI stated that there is substantial
evidence, based on its recent study of submetered electric utility load
data from 28 different sources, that the daily hot water consumption
should be less than 50 gallons. However, EPRI, as well as GAMA, the
Oregon State Energy Office, A.O. Smith, and Effikal International
(Effikal), indicated that lowering the gpd value would not alter the
relative efficiency ranking (based on energy factor) of the water
heaters, but would impose an additional cost burden on industry for
retesting and relabeling. The five commenters, therefore, suggested
that DOE maintain the current daily hot water usage of 64.3 gpd in the
test procedure. GAMA also suggested that, if necessary, it is possible
to use linear estimation of energy consumption based on a different
daily usage. The Oregon Energy Office suggested that the variation of
the daily usage value with individual consumers is quite large, and the
current 64.3 gpd may not be too far from the average. (EPRI, No. 56 at
13 and February 1997 Transcript at 221 and at Appendix J at 2; GAMA,
February 1997 Transcript at 215; Oregon State Energy Office, February
1997 Transcript at 219; A.O. Smith, February 1997 Transcript at 220;
Effikal, February 1997 Transcript at 224; and Oregon, No. 51 at 4.)
The Department believes that the current value of 64.3 gpd is
useful in determining an energy factor for consumers to use to compare
water heaters. The Department believes that revising the value so it
can be used to estimate or predict energy consumption will require a
more detailed evaluation of individual installation locations,
thermostat settings, and use patterns. Based on the fact that a revised
daily hot water usage has not been agreed upon, and that the industry
would be financially burdened, the Department concludes that revising
the daily hot water usage is unwarranted in today's Final Rule.
b. Storage Tank Temperature. The existing test procedure uses a
thermostat setting of 135 deg.F 5 deg.F (57.2 deg.C
2.8 deg.C). DOE did not propose to revise this setting in
the 1995 proposed rulemaking. AGA suggested that the thermostat setting
be lowered to 120 deg.F 5 deg.F (48.9 deg.C
2.8 deg.C) to reflect the manufacturers' recommendation to consumers to
lower the temperature settings on water heaters thus preventing
potential scalding. (AGA, No. 25 at 4.)
Both Virginia Power and Bock Water Heaters also supported lowering
the current thermostat setting to 120 deg.F (48.9 deg.C). The reasons
cited included: (1) The current setting of 135 deg.F (57.2 deg.C) does
not reflect how consumers actually operate their water heaters; (2)
most energy-related organizations advocate a setting of 120 deg.
F (48.9 deg.C) when promoting energy efficiency and safety;
(3) scalding by hot water at 135 deg.F (57.2 deg.C) is a major concern
in some areas; and (4) certain local codes restrict the thermostat
setting to be no higher than 120 deg.F (48.9 deg.C). EEI stated that
for several years many customers have been told to set their
thermostats at 120 deg.F (48.9 deg.C). (Virginia Power, No. 50 at 3 and
February 1997 Transcript at 212 and 223; Bock Water Heaters, February
1997 Transcript at 207 and 211; and EEI, February 1997 Transcript at
201.)
In contrast, six commenters, individually or in support of another
commenter's position, opposed lowering the thermostat setting from
135 deg.F 5 deg.F (57.2 deg.C 2.8 deg.C).
(EPRI, No. 56 at 2 and February 1997 Transcript at 199, 208, and 218
and at Appendix J at 1; GAMA, February 1997 Transcript at 215 and at
Appendix I at 3; Oregon State Energy Office, No. 51 at 4 and February
1997 Transcript at 201, 204, and 219; Group Thermo, February 1997
Transcript at 206; A.O. Smith, February 1997 Transcript at 220; and
Effikal International, February 1997 Transcript at 224.) Their various
comments are: (1) A setting at 120 deg.F (48.9 deg.C) could pose a
potential health risk (e.g., legionella) to consumers; (2) a setting at
135 deg.F (57.2 deg.C) is necessary to meet consumers' expected hot
water needs (as with machine-use for washing clothes); (3) a setting at
135 deg.F (57.2 deg.C) reflects realistic household settings; and (4)
changing the thermostat setting from 135 deg.F (57.2 deg.C) will not
alter the comparative ranking of water heaters but would result in a
substantial cost to industry in retesting and relabeling. EEI stated
that it would not object if the current requirement in the test
procedure is not revised. (EEI, February 1997 Transcript at 220.)
Based on the comments in the record regarding actual field
thermostat setting by consumers, potential health concerns and the
potential burden on industry, the Department concludes that revision of
the thermostat setting from 135 deg.F 5 deg.F (57.2 deg.C
2.8 deg.C) to 120 deg.F 5 deg.F (48.9 deg.C
2.8 deg.C) is unwarranted in today's Final Rule.
c. Ambient Air Temperature. The current DOE test procedure
specifies ambient air temperature for heat pump water heaters to be
67\1/2\ deg.F 1 deg.F (19.7 deg.C 0.6 deg.C)
and for all other water heater types to be between 65 deg. F
(18.3 deg.C) and 70 deg. F (21.1 deg.C) . DOE did not propose a change
to these values. EPRI stated that the existing ambient air temperature
values are satisfactory, but suggested using a nationwide survey to
determine more representative ambient air temperature values. (EPRI,
No. 56. at 5.) DOE believes a survey is unnecessary and will continue
to use the current values.
d. Supply Water Temperature. The current DOE test procedure
specifies supply water temperature to be 58 deg.F 2 deg.F
(14.4 deg.C 1.1 deg.C). DOE did not propose a change to
this value. EPRI stated that the existing supply water temperature
value is satisfactory, but suggested revisiting the value periodically
because of the possible change of the average source temperature caused
by regional shifts in the population. (EPRI, No. 56 at 5 and 6.) DOE
believes the current value for supply water temperature is appropriate
and that changing it would place an unreasonable burden on
manufacturers.
e. Relative Humidity. The current DOE test procedure specifies
relative humidity for heat pump water heaters to be between 49% and
51%. DOE did not propose a change to this value. EPRI stated that the
existing humidity value is satisfactory, but suggested using weighted
regional averages in the future to account for humidity extremes.
(EPRI, No. 56 at 5 and 6.) DOE believes the current value for humidity
is appropriate and that changing it would place an unreasonable burden
on manufacturers.
8. Cost-Based Correction Factor for Fossil-Fueled Residential
Appliances
The current procedure provides a test method to measure the energy
efficiency of water heaters that is used to rate units of similar
volumes for comparison purposes. This measure of energy efficiency is
known as the energy factor (EF). DOE did not propose any amendment to
the existing test method in the Proposed Rule.
AGA commented that because the energy factor is calculated from
measurements of the consumption of energy at the site, the EF for
fossil-fueled water heaters is substantially lower than the EF for
electric water heaters. AGA also stated that gas-fired water heaters
typically cost consumers considerably less to operate. AGA stated
[[Page 26007]]
that there is no correlation between the current energy descriptor and
the cost of operation. AGA believes this inconsistency between the
energy descriptor and cost of operation can be extremely misleading to
the consumer if a purchase decision is based primarily on the energy
factor or annual energy consumption. Therefore, AGA suggested that the
energy usage of the water heater be adjusted by a multiplication factor
of 0.298 which represents the ratio of the average cost of fossil fuel
to electricity. (AGA, No. 25 at 5.)
The 0.298 factor is the inverse of DOE's F-factor of 3.36 which was
proposed in the furnaces/boilers, vented home heating equipment and
pool heaters test procedures. The F-factor would have allowed the
consumption of fossil fuel and electricity to be combined into a single
value by placing the two energy types on a common basis. (60 FR 4348,
January 20, 1995.)
In response to disagreement from an overwhelming majority of
commenters regarding the proposed F-factor, the Department stated that
the Energy Policy and Conservation Act, as amended, requires the energy
efficiency of a furnace to be based on consumption of energy at the
site per the definition of ``energy use,'' 42 U.S.C. 6291(4). The
Department also concluded that the statute does not permit the
promulgation of an energy efficiency standard that is expressed in
terms of annual operating costs of the furnace. Based on this analysis,
the Department withdrew the proposed F-Factor in its Final Rule
Regarding Test Procedures for Furnaces/Boilers, Vented Home Heating
Equipment and Pool Heaters. (62 FR 26140, May 12, 1997.) Likewise, DOE
will not adjust the energy factor for electric water heaters to a
source basis as proposed by AGA.
III. Procedural Requirements
A. Review Under the National Environmental Policy Act of 1969
In this rule, the Department will finalize amendments to test
procedures that may be used to implement future energy conservation
standards for water heaters. The Department has determined that this
rule falls into a class of actions that are categorically excluded from
review under the National Environmental Policy Act of 1969 (NEPA), 42
U.S.C. 4321 et seq. The rule is covered by Categorical Exclusion A5,
for rulemakings that interpret or amend an existing rule without
changing the environmental effect, as set forth in the Department's
NEPA regulations at Appendix A to Subpart D, 10 CFR part 1021. This
Final Rule will not affect the quality or distribution of energy usage
and, therefore, will not result in any environmental impacts.
Accordingly, neither an environmental impact statement nor an
environmental assessment is required.
B. Review Under Executive Order 12866, ``Regulatory Planning and
Review'
Today's Final Rule is not a ``significant regulatory action'' under
Executive Order 12866, ``Regulatory Planning and Review.'' 58 FR 51735
(October 4, 1993). Accordingly, today's action is not subject to review
under the Executive Order by the Office of Information and Regulatory
Affairs.
C. Review Under the Regulatory Flexibility Act of 1980
The Regulatory Flexibility Act of 1980, 5 U.S.C. 601-612, requires
that an agency prepare an initial regulatory flexibility analysis for
any rule, for which a general notice of proposed rulemaking is
required, that would have a significant economic effect on small
entities unless the agency certifies that the rule, if promulgated,
will not have a significant economic impact on a substantial number of
small entities. 5 U.S.C. 605. DOE certified in the notice of proposed
rulemaking that the rule would not have a significant economic impact
on a substantial number of small entities. DOE estimates there are
approximately 7 manufacturers of water heaters for specialty markets
that may be small entities as defined in the Regulatory Flexibility
Act. The manufacturers of heat pump water heaters and storage-type
water heaters already make the types of measurements required by this
rule, and the cost of compliance will be negligible. Today's revised
test procedures will have no immediate impact on manufacturers of
instantaneous water heaters because there currently are no energy
efficiency standards for instantaneous water heaters; in any event, the
cost of compliance would not be significant. DOE received no comments
on its certification in the proposed rule.
D. ``Takings'' Assessment Review
DOE has determined pursuant to Executive Order 12630,
``Governmental Actions and Interference with Constitutionally Protected
Property Rights,'' 53 FR 8859 (March 18, 1988), that this regulation,
if adopted, would not result in any takings which might require
compensation under the Fifth Amendment to the United States
Constitution.
E. Federalism Review
Executive Order 12612, ``Federalism,'' 52 FR 41685 (October 30,
1987), requires that regulations, rules, legislation, and any other
policy actions be reviewed for any substantial direct effects on
States, on the relationship between the Federal Government and the
States, or in the distribution of power and responsibilities among
various levels of Government. If there are substantial direct effects,
then this Executive Order requires preparation of a Federalism
assessment to be used in all decisions involved in promulgating and
implementing a policy action.
The Final Rule published today would not regulate the States.
Accordingly, DOE has determined that preparation of a Federalism
assessment is unnecessary.
F. Review Under the Paperwork Reduction Act
No new information or record keeping requirements are imposed by
this rulemaking. Accordingly, no OMB clearance is required under the
Paperwork Reduction Act, 44 U.S.C. 3501 et seq.
G. Review Under Executive Order 12988, ``Civil Justice Reform''
With respect to the review of existing regulations and the
promulgation of new regulations, section 3(a) of Executive Order 12988,
``Civil Justice Reform,'' 61 FR 4729 (February 7, 1996), imposes on
executive agencies the following requirements: (1) Eliminate drafting
errors and ambiguity; (2) write regulations to minimize litigation; and
(3) provide a clear legal standard for affected conduct rather than a
general standard and promote simplification and burden reduction. With
regard to the review required by sections 3(a) and 3(b) of the
Executive Order specifically requires that Executive agencies make
every reasonable effort to ensure that the regulation: (1) Clearly
specifies the preemptive effect, if any; (2) clearly specifies any
effect on existing Federal law or regulation; (3) provides a clear
legal standard for affected conduct while promoting simplification and
reducing burdens; (4) specifies the retroactive effect, if any; (5)
adequately defines key terms; and (6) addresses other important issues
affecting clarity and general draftsmanship under any guidelines issued
by the Attorney General. Section 3(c) of the Executive Order requires
Executive agencies to review regulations in light of applicable
standards in sections 3(a) and 3(b) to determine whether they are met
or it is unreasonable to meet one or more of
[[Page 26008]]
them. DOE reviewed today's rule under the standards of section 3 of the
Executive Order and determined that, to the extent permitted by law, it
meets the requirements of those standards.
H. Review Under the Unfunded Mandates Reform Act of 1995
Title II of the Unfunded Mandates Reform Act of 1995, 2 U.S.C. 1531
et seq., requires each Federal agency, to the extent permitted by law,
to prepare a written assessment of the effects of any Federal mandate
in a final agency rule that may result in the expenditure by State,
local, and tribal governments, in the aggregate, or by the private
sector, of $100 million or more (adjusted annually for inflation) in
one year.
The Department has determined that this Final Rule does not include
any requirements that would result in the expenditure of money by
State, local, and tribal governments. It also would not result in costs
to the private sector of $100 million or more in any one year.
Therefore, the requirements of the Unfunded Mandates Reform Act of 1995
do not apply to this rulemaking.
I. Congressional Notification
Consistent with Subtitle E of the Small Business Regulatory
Enforcement Fairness Act of 1996, 5 U.S.C. 801-808, DOE will submit to
Congress a report regarding the issuance of today's Final Rule prior to
the effective date set forth at the outset of this notice. The report
will note the Office of Management and Budget's determination that this
rule does not constitute a ``major rule'' under that Act. 5 U.S.C. 801,
804.
List of Subjects in 10 CFR Part 430
Administrative practice and procedure, Energy conservation,
Household appliances.
Issued in Washington, D.C., on April 6, 1998.
Dan W. Reicher,
Assistant Secretary, Energy Efficiency and Renewable Energy.
For the reasons set forth in the preamble, Part 430 of Chapter II
of Title 10 of the Code of Federal Regulations is amended as set forth
below:
PART 430--ENERGY CONSERVATION PROGRAM FOR CONSUMER PRODUCTS
1. The authority citation for Part 430 continues to read as
follows:
Authority: Part B, Title III, Energy Policy and Conservation
Act, (42 U.S.C. 6291-6309), as amended.
2. Appendix E to Subpart B of Part 430 is revised to read as
follows:
Appendix E to Subpart B of Part 430--Uniform Test Method for Measuring
the Energy Consumption of Water Heaters
1. Definitions
1.1 Cut-in means the time when or water temperature at which a
water heater control or thermostat acts to increase the energy or
fuel input to the heating elements, compressor, or burner.
1.2 Cut-out means the time when or water temperature at which a
water heater control or thermostat acts to reduce to a minimum the
energy or fuel input to the heating elements, compressor, or burner.
1.3 Design Power Rating means the nominal power rating that a
water heater manufacturer assigns to a particular design of water
heater, expressed in kilowatts or Btu (kJ) per hour as appropriate.
1.4 Energy Factor means a measure of water heater overall
efficiency.
1.5 First-Hour Rating means an estimate of the maximum volume
of ``hot'' water that a storage-type water heater can supply within
an hour that begins with the water heater fully heated (i.e., with
all thermostats satisfied). It is a function of both the storage
volume and the recovery rate.
1.6 Heat Trap means a device which can be integrally connected
or independently attached to the hot and/or cold water pipe
connections of a water heater such that the device will develop a
thermal or mechanical seal to minimize the recirculation of water
due to thermal convection between the water heater tank and its
connecting pipes.
1.7 Instantaneous Water Heaters
1.7.1 Electric Instantaneous Water Heater Reserved.
1.7.2 Gas Instantaneous Water Heater means a water heater that
uses gas as the energy source, initiates heating based on sensing
water flow, is designed to deliver water at a controlled temperature
of less than 180 deg.F (82 deg.C), has an input greater than 50,000
Btu/h (53 MJ/h) but less than 200,000 Btu/h (210 MJ/h), and has a
manufacturer's specified storage capacity of less than 2 gallons
(7.6 liters). The unit may use a fixed or variable burner input.
1.8 Maximum gpm (L/min) Rating means the maximum gallons per
minute (liters per minute) of hot water that can be supplied by an
instantaneous water heater while maintaining a nominal temperature
rise of 77 deg.F (42.8 deg.C) during steady state operation.
1.9 Rated Storage Volume means the water storage capacity of a
water heater, in gallons (liters), as specified by the manufacturer.
1.10 Recovery Efficiency means the ratio of energy delivered to
the water to the energy content of the fuel consumed by the water
heater.
1.11 Standby means the time during which water is not being
withdrawn from the water heater. There are two standby time
intervals used within this test procedure:
stby,1 represents the elapsed time between the
time at which the maximum mean tank temperature is observed after
the sixth draw and subsequent recovery and the end of the 24-hour
test; stby,2 represents the total time during
the 24-hour simulated use test when water is not being withdrawn
from the water heater.
1.12 Storage-type Water Heaters
1.12.1 Electric Storage-type Water Heater means a water heater
that uses electricity as the energy source, is designed to heat and
store water at a thermostatically controlled temperature of less
than 180 deg.F (82 deg.C), has a nominal input of 12 kilowatts
(40,956 Btu/h) or less, and has a rated storage capacity of not less
than 20 gallons (76 liters) nor more than 120 gallons (450 liters).
1.12.2 Gas Storage-type Water Heater means a water heater that
uses gas as the energy source, is designed to heat and store water
at a thermostatically controlled temperature of less than 180 deg.F
(82 deg.C), has a nominal input of 75,000 Btu (79 MJ) per hour or
less, and has a rated storage capacity of not less than 20 gallons
(76 liters) nor more than 100 gallons (380 liters).
1.12.3 Heat Pump Water Heater means a water heater that uses
electricity as the energy source, is designed to heat and store
water at a thermostatically controlled temperature of less than
180 deg.F (82 deg.C), has a maximum current rating of 24 amperes
(including the compressor and all auxiliary equipment such as fans,
pumps, controls, and, if on the same circuit, any resistive
elements) for an input voltage of 250 volts or less, and, if the
tank is supplied, has a manufacturer's rated storage capacity of 120
gallons (450 liters) or less. Resistive elements used to provide
supplemental heating may use the same circuit as the compressor if
(1) an interlocking mechanism prevents concurrent compressor
operation and resistive heating or (2) concurrent operation does not
result in the maximum current rating of 24 amperes being exceeded.
Otherwise, the resistive elements and the heat pump components must
use separate circuits. A heat pump water heater may be sold by the
manufacturer with or without a storage tank.
a. Heat Pump Water Heater with Storage Tank means an air-to-
water heat pump sold by the manufacturer with an insulated storage
tank as a packaged unit. The tank and heat pump can be an integral
unit or they can be separated.
b. Heat Pump Water Heater without Storage Tank (also called Add-
on Heat Pump Water Heater) means an air-to-water heat pump designed
for use with a storage-type water heater or a storage tank that is
not specified or supplied by the manufacturer.
1.12.4 Oil Storage-type Water Heater means a water heater that
uses oil as the energy source, is designed to heat and store water
at a thermostatically controlled temperature of less than 180 deg.F
(82 deg.C), has a nominal energy input of 105,000 Btu/h (110 MJ/h)
or less, and has a manufacturer's rated storage capacity of 50
gallons (190 liters) or less.
1.12.5 Storage-type Water Heater of More than 2 Gallons (7.6
Liters) and Less than 20 Gallons (76 Liters). Reserved.
1.13 ASHRAE Standard 41.1-86 means the standard published in
1986 by the American Society of Heating, Refrigerating and Air-
Conditioning Engineers, Inc., and titled Standard Measurement Guide:
Section on Temperature Measurements.
1.14 ASTM-D-2156-80 means the test standard published in 1980
by the American
[[Page 26009]]
Society for Testing and Measurements and titled ``Smoke Density in
Flue Gases from Burning Distillate Fuels, Test Method for''.
1.15 Symbol Usage The following identity relationships are
provided to help clarify the symbology used throughout this
procedure:
Cp specific heat capacity of water
Eannual annual energy consumption of a water heater
Ef energy factor of a water heater
Fhr first-hour rating of a storage-type water heater
Fmax maximum gpm (L/min) rating of an instantaneous water
heater rated at a temperature rise of 77 deg.F (42.8 deg.C) across
the heater
i a subscript to indicate an ith draw during a test
Mi mass of water removed during the ith draw (i=1 to 6)
of the 24-hr simulated use test
M*i for storage-type water heaters, mass of water removed
during the ith draw (i=1 to n) during the first-hour rating test
M10m for instantaneous water heaters, mass of water
removed continuously during a 10-minute interval in the maximum gpm
(L/min) rating test
n for storage-type water heaters, total number of draws during the
first-hour rating test
Q total fossil fuel and/or electric energy consumed during the
entire 24-hr simulated use test
Qd daily water heating energy consumption adjusted for
net change in internal energy
Qda adjusted daily water heating energy consumption with
adjustment for variation of tank to ambient air temperature
difference from nominal value
Qdm overall adjusted daily water heating energy
consumption including Qda and QHWD
Qhr hourly standby losses
QHW daily energy consumption to heat water over the
measured average temperature rise across the water heater
QHWD adjustment to daily energy consumption,
Qhw, due to variation of the temperature rise across the
water heater not equal to the nominal value of 77 deg.F (42.8 deg.C)
Qr energy consumption of fossil fuel or heat pump water
heaters between thermostat (or burner) cut-out prior to the first
draw and cut-out following the first draw of the 24-hr simulated use
test
Qr, max energy consumption of a modulating instantaneous
water heater between cut-out (burner) prior to the first draw and
cut-out following the first draw of the 24-hr simulated use test
Qr, min energy consumption of a modulating instantaneous
water heater from immediately prior to the fourth draw to burner
cut-out following the fourth draw of the 24-hr simulated use test
Qstby total energy consumed by the water heater during
the standby time interval
, 1
Qsu total fossil fueled and/or electric energy consumed
from the beginning of the first draw to the thermostat (or burner)
cut-out following the completion of the sixth draw during the 24-hr
simulated use test
Tmin for modulating instantaneous water heaters, steady
state outlet water temperature at the minimum fuel input rate
T0 mean tank temperature at the beginning of the 24-hr
simulated use test
T24 mean tank temperature at the end of the 24-hr
simulated use test
Ta, stby average ambient air temperature during standby
periods of the 24-hr use test
Tdel for instantaneous water heaters, average outlet
water temperature during a 10-minute continuous draw interval in the
maximum gpm (L/min) rating test
Tdel, i average outlet water temperature during the ith
draw of the 24-hr simulated use test
Tin for instantaneous water heaters, average inlet water
temperature during a 10-minute continuous draw interval in the
maximum gpm (L/min) rating test
Tin, i average inlet water temperature during the ith
draw of the 24-hr simulated use test
Tmax, 1 maximum measured mean tank temperature after cut-
out following the first draw of the 24-hr simulated use test
Tstby average storage tank temperature during the standby
period , 2
of the 24-hr use test
Tsu maximum measured mean tank temperature after cut-out
following the sixth draw of the 24-hr simulated use test
Tt, stby average storage tank temperature during the
standby period
, 1 of the 24-hr use
test
T*del, i for storage-type water heaters, average outlet
water temperature during the ith draw (i=1 to n) of the first-hour
rating test
T*max, i for storage-type water heaters, maximum outlet
water temperature observed during the ith draw (i=1 to n) of the
first-hour rating test
T*min, i for storage-type water heaters, minimum outlet
water temperature to terminate the ith draw during the first-hour
rating test
UA standby loss coefficient of a storage-type water heater
Vi volume of water removed during the ith draw (i=1 to 6)
of the 24-hr simulated use test
V* i volume of water removed during the ith draw (i=1 to
n) during the first-hour rating test
V10m for instantaneous water heaters, volume of water
removed continuously during a 10-minute interval in the maximum gpm
(L/min) rating test
Vmax steady state water flow rate of an instantaneous
water heater at the rated input to give a discharge temperature of
135 deg.F 5 deg.F (57.2 deg.C 2.8 deg.C)
Vmin steady state water flow rate of a modulating
instantaneous water heater at the minimum input to give a discharge
temperature of Tmin up to 135 deg.F 5 deg.F
(57.2 deg.C 2.8 deg.C)
Vst measured storage volume of the storage tank
Wf weight of storage tank when completely filled with
water
Wt tare weight of storage tank when completely empty of
water
nr recovery efficiency
p density of water
, 1 elapsed
time between the time the maximum mean tank temperature is observed
after the sixth draw and the end of the 24-hr simulated use test
, 2 overall
standby periods when no water is withdrawn during the 24-hr
simulated use test
2. Test Conditions
2.1 Installation Requirements. Tests shall be performed with
the water heater and instrumentation installed in accordance with
Section 4 of this appendix.
2.2 Ambient Air Temperature. The ambient air temperature shall
be maintained between 65.0 deg.F and 70.0 deg.F (18.3 deg.C and
21.1 deg.C) on a continuous basis. For heat pump water heaters, the
dry bulb temperature shall be maintained at 67.5 deg.F
1 deg.F (19.7 deg.C 0.6 deg.C) and, in addition, the
relative humidity shall be maintained between 49% and 51%.
2.3 Supply Water Temperature. The temperature of the water
being supplied to the water heater shall be maintained at 58 deg.F
2 deg.F (14.4 deg.C 1.1 deg.C) throughout
the test.
2.4 Storage Tank Temperature. The average temperature of the
water within the storage tank shall be set to 135 deg.F
5 deg.F (57.2 deg.C 2.8 deg.C).
2.5 Supply Water Pressure. During the test when water is not
being withdrawn, the supply pressure shall be maintained between 40
psig (275 kPa) and the maximum allowable pressure specified by the
water heater manufacturer.
2.6 Electrical and/or Fossil Fuel Supply.
2.6.1 Electrical. Maintain the electrical supply voltage to
within 1% of the center of the voltage range specified
by the water heater and/or heat pump manufacturer.
2.6.2 Natural Gas. Maintain the supply pressure in accordance
with the manufacturer's specifications. If the supply pressure is
not specified, maintain a supply pressure of 7-10 inches of water
column (1.7-2.5 kPa). If the water heater is equipped with a gas
appliance pressure regulator, the regulator outlet pressure shall be
within 10% of the manufacturer's specified manifold
pressure. For all tests, use natural gas having a heating value of
approximately 1,025 Btu per standard cubic foot (38,190 kJ per
standard cubic meter).
2.6.3 Propane Gas. Maintain the supply pressure in accordance
with the manufacturer's specifications. If the supply pressure is
not specified, maintain a supply pressure of 11-13 inches of water
column (2.7-3.2 kPa). If the water heater is equipped with a gas
appliance pressure regulator, the regulator outlet pressure shall be
within 10% of the manufacturer's specified manifold
pressure. For all tests, use propane gas with a heating value of
approximately 2,500 Btu per standard cubic foot (93,147 kJ per
standard cubic meter).
2.6.4 Fuel Oil Supply. Maintain an uninterrupted supply of fuel
oil. Use fuel oil
[[Page 26010]]
having a heating value of approximately 138,700 Btu per gallon
(38,660 kJ per liter).
3. Instrumentation
3.1 Pressure Measurements. Pressure-measuring instruments shall
have an error no greater than the following values:
------------------------------------------------------------------------
Item measured Instrument accuracy Instrument precision
------------------------------------------------------------------------
Gas pressure................ 0.1 0.05
inch of water inch of water
column ( 0.025 kPa). minus> 0.012 kPa).
Atmospheric pressure........ 0.1 0.05
inch of mercury inch of mercury
column ( 0.34 kPa). minus> 0.17 kPa).
Water pressure.............. 1.0 0.50
pounds per square pounds per square
inch ( inch (
6.9 kPa). 3.45 kPa).
------------------------------------------------------------------------
3.2 Temperature Measurement
3.2.1 Measurement. Temperature measurements shall be made in
accordance with the Standard Measurement Guide: Section on
Temperature Measurements, ASHRAE Standard 41.1-86.
3.2.2 Accuracy and Precision. The accuracy and precision of the
instruments, including their associated readout devices, shall be
within the following limits:
----------------------------------------------------------------------------------------------------------------
Item measured Instrument accuracy Instrument precision
----------------------------------------------------------------------------------------------------------------
Air dry bulb temperature............. 0.2 deg.F ( 0.1 deg.F ( 0.06
minus> 0.1 deg.C). deg.C)
Air wet bulb temperature............. 0.2 deg.F ( 0.1 deg.F ( 0.06
minus> 0.1 deg.C). deg.C)
Inlet and outlet water temperatures.. 0.2 deg.F ( 0.1 deg.F ( 0.06
minus> 0.1 deg.C). deg.C)
Storage tank temperatures............ 0.5 deg.F ( 0.25 deg.F ( 0.14
minus> 0.3 deg.C). deg.C)
----------------------------------------------------------------------------------------------------------------
3.2.3 Scale Division. In no case shall the smallest scale
division of the instrument or instrument system exceed 2 times the
specified precision.
3.2.4 Temperature Difference. Temperature difference between
the entering and leaving water may be measured with any of the
following:
a. A thermopile
b. Calibrated resistance thermometers
c. Precision thermometers
d. Calibrated thermistors
e. Calibrated thermocouples
f. Quartz thermometers
3.2.5 Thermopile Construction. If a thermopile is used, it
shall be made from calibrated thermocouple wire taken from a single
spool. Extension wires to the recording device shall also be made
from that same spool.
3.2.6 Time Constant. The time constant of the instruments used
to measure the inlet and outlet water temperatures shall be no
greater than 5 seconds.
3.3 Liquid Flow Rate Measurement. The accuracy of the liquid
flow rate measurement, using the calibration if furnished, shall be
equal to or less than 1% of the measured value in mass
units per unit time.
3.4 Electric Energy. The electrical energy used shall be
measured with an instrument and associated readout device that is
accurate within 1% of the reading.
3.5 Fossil Fuels. The quantity of fuel used by the water heater
shall be measured with an instrument and associated readout device
that is accurate within 1% of the reading.
3.6 Mass Measurements. For mass measurements greater than or
equal to 10 pounds (4.5 kg), a scale that is accurate within
1% of the reading shall be used to make the
measurement. For mass measurements less than 10 pounds (4.5 kg), the
scale shall provide a measurement that is accurate within
0.1 pound (0.045 kg).
3.7 Heating Value. The higher heating value of the natural gas,
propane, or fuel oil shall be measured with an instrument and
associated readout device that is accurate within 1% of
the reading. The heating value of natural gas and propane must be
corrected for local temperature and pressure conditions.
3.8 Time. The elapsed time measurements shall be measured with
an instrument that is accurate within 0.5 seconds per
hour.
3.9 Volume. Volume measurements shall be measured with an
accuracy of 2% of the total volume.
4. Installation
4.1 Water Heater Mounting. A water heater designed to be
freestanding shall be placed on a \3/4\ inch (2 cm) thick plywood
platform supported by three 2 x 4 inch (5 cm x 10 cm) runners.
If the water heater is not approved for installation on combustible
flooring, suitable non-combustible material shall be placed between
the water heater and the platform. Counter-top water heaters shall
be placed against a simulated wall section. Wall-mounted water
heaters shall be supported on a simulated wall in accordance with
the manufacturer-published installation instructions. When a
simulated wall is used, the recommended construction is 2 x 4 inch
(5 cm x 10 cm) studs, faced with \3/4\ inch (2 cm) plywood. For
heat pump water heaters that are supplied with a storage tank, the
two components, if not delivered as a single package, shall be
connected in accordance with the manufacturer-published installation
instructions and the overall system shall be placed on the above-
described plywood platform. If installation instructions are not
provided by the heat pump manufacturer, uninsulated 8 foot (2.4 m)
long connecting hoses having an inside diameter of \5/8\ inch (1.6
cm) shall be used to connect the storage tank and the heat pump
water heater. With the exception of using the storage tank described
in 4.10, the same requirements shall apply for heat pump water
heaters that are supplied without a storage tank from the
manufacturer. The testing of the water heater shall occur in an area
that is protected from drafts.
4.2 Water Supply. Connect the water heater to a water supply
capable of delivering water at conditions as specified in Sections
2.3 and 2.5 of this appendix.
4.3 Water Inlet and Outlet Configuration. For freestanding
water heaters that are taller than 36 inches (91.4 cm), inlet and
outlet piping connections shall be configured in a manner consistent
with Figures 1 and 2. Inlet and outlet piping connections for wall-
mounted water heaters shall be consistent with Figure 3. For
freestanding water heaters that are 36 inches or less in height and
not supplied as part of a counter-top enclosure (commonly referred
to as an under-the-counter model), inlet and outlet piping shall be
installed in a manner consistent with Figures 4, 5, and 6. For water
heaters that are supplied with a counter-top enclosure, inlet and
outlet piping shall be made in a manner consistent with Figures 7A
and 7B, respectively. The vertical piping noted in Figures 7A and 7B
shall be located (whether inside the enclosure or along the outside
in a recessed channel) in accordance with the manufacturer-published
installation instructions.
All dimensions noted in Figures 1 through 7 shall be achieved.
All piping between the water heater and the inlet and outlet
temperature sensors, noted as TIN and TOUT in
the figures, shall be Type ``L'' hard copper having the same
diameter as the connections on the water heater. Unions may be used
to facilitate installation and removal of the piping arrangements. A
pressure gauge and diaphragm expansion tank shall be installed in
the supply water piping at a location upstream of the inlet
temperature sensor. An appropriately rated pressure and temperature
relief valve shall be installed on all water heaters at the port
specified by the manufacturer. Discharge piping for the relief valve
shall be non-metallic. If heat traps, piping insulation, or pressure
relief valve insulation are supplied with the water heater, they
shall be installed for testing. Except when using a simulated wall,
clearance shall be provided such that none of the piping contacts
other surfaces in the test room.
4.4 Fuel and/or Electrical Power and Energy Consumption.
Install one or more
[[Page 26011]]
instruments which measure, as appropriate, the quantity and rate of
electrical energy and/or fossil fuel consumption in accordance with
Section 3. For heat pump water heaters that use supplemental
resistive heating, the electrical energy supplied to the resistive
element(s) shall be metered separately from the electrical energy
supplied to the entire appliance or to the remaining components
(e.g., compressor, fans, pumps, controls).
4.5 Internal Storage Tank Temperature Measurements. Install six
temperature measurement sensors inside the water heater tank with a
vertical distance of at least 4 inches (100 mm) between successive
sensors. A temperature sensor shall be positioned at the vertical
midpoint of each of the six equal volume nodes within the tank.
Nodes designate the equal volumes used to evenly partition the total
volume of the tank. As much as is possible, the temperature sensor
should be positioned away from any heating elements, anodic
protective devices, tank walls, and flue pipe walls. If the tank
cannot accommodate six temperature sensors and meet the installation
requirements specified above, install the maximum number of sensors
which comply with the installation requirements. The temperature
sensors shall be installed either through (1) the anodic device
opening; (2) the relief valve opening; or (3) the hot water outlet.
If installed through the relief valve opening or the hot water
outlet, a tee fitting or outlet piping, as applicable, shall be
installed as close as possible to its original location. If the
relief valve temperature sensor is relocated, and it no longer
extends into the top of the tank, a substitute relief valve that has
a sensing element that can reach into the tank shall be installed.
If the hot water outlet includes a heat trap, the heat trap shall be
installed on top of the tee fitting. Added fittings shall be covered
with thermal insulation having an R value between 4 and 8
hft2 deg.F/Btu (0.7 and 1.4
m2 deg.C/W).
4.6 Ambient Air Temperature Measurement. Install an ambient air
temperature sensor at the vertical mid-point of the water heater and
approximately 2 feet (610 mm) from the surface of the water heater.
The sensor shall be shielded against radiation.
4.7 Inlet and Outlet Water Temperature Measurements. Install
temperature sensors in the cold-water inlet pipe and hot-water
outlet pipe as shown in Figures 1, 2, 3, 4, 5, 6, 7a and 7b, as
applicable.
4.8 Flow Control. A valve shall be installed to provide flow as
specified in sections 5.1.4.1 for storage tank water heaters and
5.2.1 for instantaneous water heaters.
4.9 Flue Requirements.
4.9.1 Gas-Fired Water Heaters. Establish a natural draft in the
following manner. For gas-fired water heaters with a vertically
discharging draft hood outlet, a 5-foot (1.5-meter) vertical vent
pipe extension with a diameter equal to the largest flue collar size
of the draft hood shall be connected to the draft hood outlet. For
gas-fired water heaters with a horizontally discharging draft hood
outlet, a 90-degree elbow with a diameter equal to the largest flue
collar size of the draft hood shall be connected to the draft hood
outlet. A 5-foot (1.5-meter) length of vent pipe shall be connected
to the elbow and oriented to discharge vertically upward. Direct
vent gas-fired water heaters shall be installed with venting
equipment specified in the manufacturer's instructions using the
minimum vertical and horizontal lengths of vent pipe recommended by
the manufacturer.
4.9.2 Oil-Fired Water Heaters. Establish a draft at the flue
collar at the value specified in the manufacturer's instructions.
Establish the draft by using a sufficient length of vent pipe
connected to the water heater flue outlet, and directed vertically
upward. For an oil-fired water heater with a horizontally
discharging draft hood outlet, a 90-degree elbow with a diameter
equal to the largest flue collar size of the draft hood shall be
connected to the draft hood outlet. A length of vent pipe sufficient
to establish the draft shall be connected to the elbow fitting and
oriented to discharge vertically upward. Direct-vent oil-fired water
heaters should be installed with venting equipment as specified in
the manufacturer's instructions, using the minimum vertical and
horizontal lengths of vent pipe recommended by the manufacturer.
4.10 Heat Pump Water Heater Storage Tank. The tank to be used
for testing a heat pump water heater without a tank supplied by the
manufacturer (see Section 1.12.3b) shall be an electric storage-type
water heater having a measured volume of 47.0 gallons
1.0 gallon (178 liters 3.8 liters); two 4.5
kW heating elements controlled in such a manner as to prevent both
elements from operating simultaneously; and an energy factor greater
than or equal to the minimum energy conservation standard (as
determined in accordance with Section 6.1.7) and less than or equal
to the sum of the minimum energy conservation standard and 0.02.
5. Test Procedures
5.1 Storage-type Water Heaters, Including Heat Pump Water
Heaters.
5.1.1 Determination of Storage Tank Volume. Determine the
storage capacity, Vst, of the water heater under test, in
gallons (liters), by subtracting the tare weight--measured while the
tank is empty--from the gross weight of the storage tank when
completely filled with water (with all air eliminated and line
pressure applied as described in section 2.5) and dividing the
resulting net weight by the density of water at the measured
temperature.
5.1.2 Setting the Thermostat.
5.1.2.1 Single Thermostat Tanks. Starting with a tank at the
supply water temperature, initiate normal operation of the water
heater. After cut-out, determine the mean tank temperature every
minute until the maximum value is observed. Determine whether this
maximum value for the mean tank temperature is within the range of
135 deg.F5 deg.F (57.2 deg.C2.8 deg.C). If
not, turn off the water heater, adjust the thermostat, drain and
refill the tank with supply water. Then, once again, initiate normal
operation of the water heater, and determine the maximum mean tank
temperature after cut-out. Repeat this sequence until the maximum
mean tank temperature after cut-out is 135 deg.F5 deg.F
(57.2 deg.C2.8 deg.C).
5.1.2.2 Tanks with Two or More Thermostats. Follow the same
sequence as for a single thermostat tank, i.e. start at the supply
water temperature, operate normally until cutout. Determine if the
thermostat that controls the uppermost heating element yields a
maximum water temperature of 135 deg.F5 deg.F
(57.2 deg.C2.8 deg.C), as measured by the in-tank
sensors that are positioned above the uppermost heating element. If
the tank temperature at the thermostat is not within
135 deg.F5 deg.F (57.2 deg.C2.8 deg.C), turn
off the water heater, adjust the thermostat, drain and refill the
tank with supply water. The thermostat that controls the heating
element positioned next highest in the tank shall then be set to
yield a maximum water temperature of 135 deg.F5 deg.F
(57.2 deg.C2.8 deg.C). This process shall be repeated
until the thermostat controlling the lowest element is correctly
adjusted. When adjusting the thermostat that controls the lowest
element, the maximum mean tank temperature after cut-out, as
determined using all the in-tank sensors, shall be
135 deg.F5 deg.F (57.2 deg.C2.8 deg.C). When
adjusting all other thermostats, use only the in-tank temperature
sensors positioned above the heating element in question to evaluate
the maximum water temperature after cut-out.
For heat pump water heaters that control an auxiliary resistive
element, the thermostat shall be set in accordance with the
manufacturer's installation instructions.
5.1.3 Power Input Determination. For all water heaters except
electric types having immersed heating elements, initiate normal
operation and determine the power input, P, to the main burners
(including pilot light power, if any) after 15 minutes of operation.
If the water heater is equipped with a gas appliance pressure
regulator, the regulator outlet pressure shall be set within
10% of that recommended by the manufacturer. For oil-
fired water heaters the fuel pump pressure shall be within
10% of the manufacturer's specified pump pressure. All
burners shall be adjusted to achieve an hourly Btu (kJ) rating that
is within 2% of the value specified by the
manufacturer. For an oil-fired water heater, adjust the burner to
give a CO2 reading recommended by the manufacturer and an
hourly Btu (kJ) rating that is within 2% of that
specified by the manufacturer. Smoke in the flue may not exceed No.
1 smoke as measured by the procedure in ASTM-D-2156-80.
5.1.4 First-Hour Rating Test.
5.1.4.1 General. During hot water draws, remove water at a rate
of 3.00.25 gallons per minute (11.40.95
liters per minute). Collect the water in a container that is large
enough to hold the volume removed during an individual draw and
suitable for weighing at the termination of each draw.
Alternatively, a water meter may be used to directly measure the
water volume(s) withdrawn.
5.1.4.2 Draw Initiation Criteria. Begin the first-hour rating
test by imposing a draw on the storage-type water heater. After
completion of this first draw, initiate successive draws based on
the following criteria. For gas-and oil-fired water heaters,
initiate successive draws when the thermostat acts to reduce the
supply of fuel to the main burner. For electric water heaters having
a single element or multiple elements that all operate
simultaneously, initiate
[[Page 26012]]
successive draws when the thermostat acts to reduce the electrical
input supplied to the element(s). For electric water heaters having
two or more elements that do not operate simultaneously, initiate
successive draws when the applicable thermostat acts to reduce the
electrical input to the element located vertically highest in the
storage tank. For heat pump waters heaters that do not use
supplemental resistive heating, initiate successive draws
immediately after the electrical input to the compressor is reduced
by the action of the water heater's thermostat. For heat pump waters
heaters that use supplemental resistive heating, initiate successive
draws immediately after the electrical input to the compressor or
the uppermost resistive element is reduced by the action of the
applicable water heater thermostat. This draw initiation criterion
for heat pump water heaters that use supplemental resistive heating,
however, shall only apply when the water located above the
thermostat at cut-out is heated to 135 deg.F5 deg.F
(57.2 deg.C2.8 deg.C).
5.1.4.3 Test Sequence. Establish normal water heater operation.
If the water heater is not presently operating, initiate a draw. The
draw may be terminated anytime after cut-in occurs. After cut-out
occurs (i.e., all thermostats are satisfied), monitor the internal
storage tank temperature sensors described in section 4.5 every
minute.
Initiate a draw after a maximum mean tank temperature has been
observed following cut-out. Record the time when the draw is initiated
and designate it as an elapsed time of zero (* = 0). (The
superscript * is used to denote variables pertaining to the first-hour
rating test.) Record the outlet water temperature beginning 15 seconds
after the draw is initiated and at 5-second intervals thereafter until
the draw is terminated. Determine the maximum outlet temperature that
occurs during this first draw and record it as T*max, 1. For
the duration of this first draw and all successive draws, in addition,
monitor the inlet temperature to the water heater to ensure that the
required 58 deg.F2 deg.F (14.4 deg.C1.1 deg.C)
test condition is met. Terminate the hot water draw when the outlet
temperature decreases to T*max,1-25 deg.F
(T*max,1-13.9 deg.C). Record this temperature as
T*min,1. Following draw termination, determine the average
outlet water temperature and the mass or volume removed during this
first draw and record them as T*del,1 and M*1 or
V*1, respectively.
Initiate a second and, if applicable, successive draw each time the
applicable draw initiation criteria described in section 5.1.4.2 are
satisfied. As required for the first draw, record the outlet water
temperature 15 seconds after initiating each draw and at 5-second
intervals thereafter until the draw is terminated. Determine the
maximum outlet temperature that occurs during each draw and record it
as T*max, i, where the subscript i refers to the draw
number. Terminate each hot water draw when the outlet temperature
decreases to T*max, i-25 deg.F
(T*max, i-13.9 deg.C). Record this temperature as
T*min, i. Calculate and record the average outlet
temperature and the mass or volume removed during each draw
(T*del, i and M*i or V*i,
respectively). Continue this sequence of draw and recovery until one
hour has elapsed, then shut off the electrical power and/or fuel
supplied to the water heater.
If a draw is occurring at an elapsed time of one hour, continue
this draw until the outlet temperature decreases to
T*max, n-25 deg.F (T*max, n -13.9 deg.C), at
which time the draw shall be immediately terminated. (The subscript n
shall be used to denote quantities associated with the final draw.) If
a draw is not occurring at an elapsed time of one hour, a final draw
shall be imposed at one hour. This draw shall be immediately terminated
when the outlet temperature first indicates a value less than or equal
to the cut-off temperature used for the previous draw
(T*min, n-1). For cases where the outlet temperature is
close to T*min, n-1, the final draw shall proceed for a
minimum of 30 seconds. If an outlet temperature greater than
T*min, n-1 is not measured within 30 seconds, the draw shall
be immediately terminated and zero additional credit shall be given
towards first-hour rating (i.e., M*n = 0 or V*n =
0). After the final draw is terminated, calculate and record the
average outlet temperature and the mass or volume removed during the
draw (T*del, n and M*n or V*n,
respectively).
5.1.5 24-Hour Simulated Use Test. During the simulated use
test, a total of 64.3 1.0 gallons (2433.8
liters) shall be removed. This value is referred to as the daily hot
water usage in the following text.
With the water heater turned off, fill the water heater with
supply water and apply pressure as described in section 2.5. Turn on
the water heater and associated heat pump unit, if present. After
the cut-out occurs, the water heater may be operated for up to three
cycles of drawing until cut-in, and then operating until cut-out,
prior to the start of the test.
At this time, record the mean tank temperature (To),
and the electrical and/or fuel measurement readings, as appropriate.
Begin the 24-hour simulated use test by withdrawing a volume from
the water heater that equals one-sixth of the daily hot water usage.
Record the time when this first draw is initiated and assign it as
the test elapsed time () of zero (0). Record the average
storage tank and ambient temperature every 15 minutes throughout the
24-hour simulated use test unless a recovery or a draw is occurring.
At elapsed time intervals of one, two, three, four, and five hours
from = 0, initiate additional draws, removing an amount of
water equivalent to one-sixth of the daily hot water usage with the
maximum allowable deviation for any single draw being
0.5 gallons (1.9 liters). The quantity of water withdrawn during the
sixth draw shall be increased or decreased as necessary such that
the total volume of water withdrawn equals 64.3 gallons
1.0 gallon (243.4 liters 3.8 liters).
All draws during the simulated use test shall be made at flow
rates of 3.0 gallons 0.25 gallons per minute (11.4
liters 0.95 liters per minute). Measurements of the
inlet and outlet temperatures shall be made 15 seconds after the
draw is initiated and at every subsequent 5-second interval
throughout the duration of each draw. The arithmetic mean of the hot
water discharge temperature and the cold water inlet temperature
shall be determined for each draw (Tdel, i and
Tin, i). Determine and record the net mass or volume
removed (Mi or Vi ), as appropriate, after
each draw.
At the end of the recovery period following the first draw,
record the maximum mean tank temperature observed after cut-out,
Tmax, 1, and the energy consumed by an electric
resistance, gas or oil-fired water heater, Qr. For heat
pump water heaters, the total electrical energy consumed during the
first recovery by the heat pump (including compressor, fan,
controls, pump, etc.) and, if applicable, by the resistive
element(s) shall be recorded as Qr.
At the end of the recovery period that follows the sixth draw,
determine and record the total electrical energy and/or fossil fuel
consumed since the beginning of the test, Qsu. In
preparation for determining the energy consumed during standby,
record the reading given on the electrical energy (watt-hour) meter,
the gas meter, and/or the scale used to determine oil consumption,
as appropriate. Record the maximum value of the mean tank
temperature after cut-out as Tsu. Except as noted below,
allow the water heater to remain in the standby mode until 24 hours
have elapsed from the start of the test (i.e., since = 0). Prevent
the water heater from beginning a recovery cycle during the last
hour of the test by turning off the electric power to the electrical
heating elements and heat pump, if present, or by turning down the
fuel supply to the main burner at an elapsed time of 23 hours. If a
recovery is taking place at an elapsed time of 23 hours, wait until
the recovery is complete before reducing the electrical and/or fuel
supply to the water heater. At 24 hours, record the mean tank
temperature, T24, and the electric and/or fuel instrument
readings. Determine the total fossil fuel or electrical energy
consumption, as appropriate, for the entire 24-hour simulated use
test, Q. Record the time interval between the time at which the
maximum mean tank temperature is observed after the sixth draw and
the end of the 24-hour test as stby, 1. Record the time
during which water is not being withdrawn from the water heater
during the entire 24-hour period as stby, 2.
5.2 Instantaneous Gas and Electric Water Heaters
5.2.1 Setting the Outlet Discharge Temperature. Initiate normal
operation of the water heater at the full input rating for electric
instantaneous water heaters and at
[[Page 26013]]
the maximum firing rate specified by the manufacturer for gas
instantaneous water heaters. Monitor the discharge water temperature
and set to a value of 135 deg.F 5 deg.F (57.2 deg.C
2.8 deg.C) in accordance with the manufacturer's
instructions. If the water heater is not capable of providing this
discharge temperature when the flow rate is 3.0 gallons
0.25 gallons per minute (11.4 liters 0.95 liters per
minute), then adjust the flow rate as necessary to achieve the
specified discharge water temperature. Record the corresponding flow
rate as Vmax.
5.2.2 Additional Requirements for Variable Input Instantaneous
Gas Water Heaters. If the instantaneous water heater incorporates a
controller that permits operation at a reduced input rate, adjust
the flow rate as necessary to achieve a discharge water temperature
of 135 deg.F 5 deg.F (57.2 deg.C
2.8 deg.C) while maintaining the minimum input rate. Record the
corresponding flow rate as Vmin. If an outlet temperature
of 135 deg.F 5 deg.F (57.2 deg.C
2.8 deg.C) cannot be achieved at the minimum flow rate permitted by
the instantaneous water heater, record the flow rate as
Vmin and the corresponding outlet temperature as
Tmin.
5.2.3 Maximum GPM Rating Test for Instantaneous Water Heaters.
Establish normal water heater operation at the full input rate for
electric instantaneous water heaters and at the maximum firing rate
for gas instantaneous water heaters with the discharge water
temperature set in accordance with Section 5.2.1. During the 10-
minute test, either collect the withdrawn water for later
measurement of the total mass removed, or alternatively, use a water
meter to directly measure the water volume removed.
After recording the scale or water meter reading, initiate water
flow throughout the water heater, record the inlet and outlet water
temperatures beginning 15 seconds after the start of the test and at
subsequent 5-second intervals throughout the duration of the test.
At the end of 10 minutes, turn off the water. Determine the mass of
water collected, M10m, in pounds (kilograms), or the
volume of water, V10m, in gallons (liters).
5.2.4 24-hour Simulated Use Test for Gas Instantaneous Water
Heaters.
5.2.4.1 Fixed Input Instantaneous Water Heaters. Establish
normal operation with the discharge water temperature and flow rate
set to values of 135 deg.F 5 deg.F (57.2 deg.C
2.8 deg.C) and Vmax per Section 5.2.1,
respectively. With no draw occurring, record the reading given by
the gas meter and/or the electrical energy meter as appropriate.
Begin the 24-hour simulated use test by drawing an amount of water
out of the water heater equivalent to one-sixth of the daily hot
water usage. Record the time when this first draw is initiated and
designate it as an elapsed time, , of 0. At elapsed time
intervals of one, two, three, four, and five hours from =
0, initiate additional draws, removing an amount of water equivalent
to one-sixth of the daily hot water usage, with the maximum
allowable deviation for any single draw being 0.5
gallons (1.9 liters). The quantity of water drawn during the sixth
draw shall be increased or decreased as necessary such that the
total volume of water withdrawn equals 64.3 gallons 1.0
gallons (243.4 liters 3.8 liters).
Measurements of the inlet and outlet water temperatures shall be
made 15 seconds after the draw is initiated and at every 5-second
interval thereafter throughout the duration of the draw. The
arithmetic mean of the hot water discharge temperature and the cold
water inlet temperature shall be determined for each draw. Record
the scale used to measure the mass of the withdrawn water or the
water meter reading, as appropriate, after each draw. At the end of
the recovery period following the first draw, determine and record
the fossil fuel or electrical energy consumed, Qr.
Following the sixth draw and subsequent recovery, allow the water
heater to remain in the standby mode until exactly 24 hours have
elapsed since the start of the test (i.e., since = 0). At
24 hours, record the reading given by the gas meter and/or the
electrical energy meter as appropriate. Determine the fossil fuel or
electrical energy consumed during the entire 24-hour simulated use
test and designate the quantity as Q.
5.2.4.2 Variable Input Instantaneous Water Heaters. If the
instantaneous water heater incorporates a controller that permits
continuous operation at a reduced input rate, the first three draws
shall be conducted using the maximum flow rate, Vmax,
while removing an amount of water equivalent to one-sixth of the
daily hot water usage, with the maximum allowable deviation for any
one of the three draws being 0.5 gallons (1.9 liters).
The second three draws shall be conducted at Vmin. If an
outlet temperature of 135 deg.F 5 deg.F (57.2 deg.C
2.8 deg.C) could not be achieved at the minimum flow
rate permitted by the instantaneous water heater, the last three
draws should be lengthened such that the volume removed is:
[GRAPHIC] [TIFF OMITTED] TR11MY98.001
or
[GRAPHIC] [TIFF OMITTED] TR11MY98.002
where Tmin is the outlet water temperature at the flow
rate Vmin as determined in Section 5.2.1, and where the
maximum allowable variation for any one of the three draws is
0.5 gallons (1.9 liters). The quantity of water
withdrawn during the sixth draw shall be increased or decreased as
necessary such that the total volume of water withdrawn equals
(32.15 + 31V4,5,6) 1.0
gallons
((121.7 + 3V. 4,5,6) 3.8
liters).
Measurements of the inlet and outlet water temperatures shall be
made 5 seconds after a draw is initiated and at every 5-second
interval thereafter throughout the duration of the draw. Determine
the arithmetic mean of the hot water discharge temperature and the
cold water inlet temperature for each draw. Record the scale used to
measure the mass of the withdrawn water or the water meter reading,
as appropriate, after each draw. At the end of the recovery period
following the first draw, determine and record the fossil fuel or
electrical energy consumed, Qr, max. Likewise, record the
reading of the meter used to measure fossil fuel or electrical
energy consumption prior to the fourth draw and at the end of the
recovery period following the fourth draw, and designate the
difference as Qr,min. Following the sixth draw and
subsequent recovery, allow the water heater to remain in the standby
mode until exactly 24 hours have elapsed since the start of the test
(i.e., since =0). At 24 hours, record the reading given by
the gas meter and/or the electrical energy meter, as appropriate.
Determine the fossil fuel or electrical energy consumed during the
entire 24-hour simulated use test and designate the quantity as Q.
6. Computations
6.1 Storage Tank and Heat Pump Water Heaters.
6.1.1 Storage Tank Capacity. The storage tank capacity is
computed using the following:
[GRAPHIC] [TIFF OMITTED] TR11MY98.003
Where:
Vst = the storage capacity of the water heater, gal (L).
Wf = the weight of the storage tank when completely
filled with water, lb (kg).
Wt = the (tare) weight of the storage tank when
completely empty, lb (kg).
= the density of water used to fill the tank measured at
the temperature of the water, lb/gal (kg/L).
6.1.2. First-Hour Rating Computation. For the case in which the
final draw is initiated at or prior to an elapsed time of one hour,
the first-hour rating shall be computed using,
[GRAPHIC] [TIFF OMITTED] TR11MY98.004
Where:
n = the number of draws that are completed during the first-hour
rating test.
V*i = the volume of water removed during the ith draw of
the first-hour rating test, gal (L)
or, if the mass of water is being measured,
[GRAPHIC] [TIFF OMITTED] TR11MY98.005
Where:
M*i = the mass of water removed during the ith draw of
the first-hour rating test, lb (kg).
= the water density corresponding to the average outlet
temperature measured during the ith draw, (T*del, I), lb/
gal (kg/L).
For the case in which a draw is not in progress at the elapsed
time of one hour and a final draw is imposed at the elapsed time of
one hour, the first-hour rating shall be calculated using
[[Page 26014]]
[GRAPHIC] [TIFF OMITTED] TR11MY98.006
where n and V*i are the same quantities as defined above,
and
V*n = the volume of water drawn during the nth (final)
draw of the first-hour rating test, gal (L)
T*del,n-1 = the average water outlet temperature measured
during the (n-1)th draw of the first-hour rating test, deg.F
( deg.C).
T*del,n = the average water outlet temperature measured
during the nth (final) draw of the first-hour rating test, deg.F
( deg.C).
T*min,n-1 = the minimum water outlet temperature measured
during the (n-1)th draw of the first-hour rating test, deg.F
( deg.C).
6.1.3 Recovery Efficiency. The recovery efficiency for gas,
oil, and heat pump storage-type water heaters is computed as:
[GRAPHIC] [TIFF OMITTED] TR11MY98.007
Where:
M1 = total mass removed during the first draw of the 24-
hour simulated use test, lb (kg), or, if the volume of water is
being measured,
M1 = V1 1
Where:
V1 = total volume removed during the first draw of the
24-hour simulated use test, gal (L).
1 = density of the water at the water
temperature measured at the point where the flow volume is measured,
lb/gal (kg/L).
Cp1 = specific heat of the withdrawn water,
(Tdel,1 + Tin,1) / 2, Btu/lb deg.F (kJ/
kg deg.C).
Tdel,1 = average water outlet temperature measured during
the first draw of the 24-hour simulated use test, deg.F ( deg.C).
Tin,1 = average water inlet temperature measured during
the first draw of the 24-hour simulated use test, deg.F ( deg.C).
Vst = as defined in section 6.1.1.
2 = density of stored hot water,
(Tmax,1 + To)/2, lb/gal (kg/L).
Cp2 = specific heat of stored hot water evaluated at
(Tmax,1 + To) / 2, Btu/lb deg.F (kJ/
kg+ deg.C).
Tmax,1 = maximum mean tank temperature recorded after
cut-out following the first draw of the 24-hour simulated use test,
deg.F ( deg.C).
To = maximum mean tank temperature recorded prior to the
first draw of the 24-hour simulated use test, deg.F ( deg.C).
Qr = the total energy used by the water heater between
cut-out prior to the first draw and cut-out following the first
draw, including auxiliary energy such as pilot lights, pumps, fans,
etc., Btu (kJ). (Electrical auxiliary energy shall be converted to
thermal energy using the following conversion: 1 kWh = 3,412 Btu.)
The recovery efficiency for electric water heaters with immersed
heating elements is assumed to be 98%.
6.1.4 Hourly Standby Losses. The hourly standby energy losses
are computed as:
[GRAPHIC] [TIFF OMITTED] TR11MY98.008
Where:
Qhr = the hourly standby energy losses of the water
heater, Btu/h (kJ/h).
Qstby = the total energy consumed by the water heater
between the time at which the maximum mean tank temperature is
observed after the sixth draw and the end of the 24-hour test
period, Btu (kJ).
Vst = as defined in section 6.1.1.
= density of stored hot water, (T24 +
Tsu) / 2, lb/gal (kg/L).
Cp = specific heat of the stored water, (T24 +
Tsu) / 2, Btu/lb deg.F (kJ/kg deg.C).
T24 = the mean tank temperature at the end of the 24-hour
simulated use test, deg.F ( deg.C).
Tsu = the maximum mean tank temperature observed after
the sixth draw, deg.F ( deg.C).
r = as defined in section 6.1.3.
stby, 1 = elapsed time between the time at which
the maximum mean tank temperature is observed after the sixth draw
and the end of the 24-hour simulated use test, h.
The standby heat loss coefficient for the tank is computed as:
[GRAPHIC] [TIFF OMITTED] TR11MY98.009
Where:
UA = standby heat loss coefficient of the storage tank, Btu/
h deg.F (kJ/h deg.C).
Qhr = as defined in this section.
Tt, stby,1= overall average storage tank temperature
between the time when the maximum mean tank temperature is observed
after the sixth draw and the end of the 24-hour simulated use test,
deg.F ( deg.C).
Ta, stby,1= overall average ambient temperature between
the time when the maximum mean tank temperature is observed after
the sixth draw and the end of the 24-hour simulated use test, deg.F
( deg.C).
6.1.5 Daily Water Heating Energy Consumption. The daily water
heating energy consumption, Qd, is computed as:
[GRAPHIC] [TIFF OMITTED] TR11MY98.010
Where:
Q = total energy used by the water heater during the 24-hour
simulated use test including auxiliary energy such as pilot lights,
pumps, fans, etc., Btu (kJ). (Electrical auxiliary energy shall be
converted to thermal energy using the following conversion: 1 kWh =
3,412 Btu.)
Vst = as defined in section 6.1.1.
= density of the stored hot water, (T24 +
To) / 2, lb/gal (kg/L).
Cp = specific heat of the stored water, (T24 +
To) / 2, Btu/lb deg.F (kJ/kg deg.C).
T24 = mean tank temperature at the end of the 24-hour
simulated use test, deg.F ( deg.C).
To = mean tank temperature at the beginning of the 24-
hour simulated use test, recorded one minute before the first draw
is initiated, deg.F ( deg.C).
r = as defined in section 6.1.3.
6.1.6 Adjusted Daily Water Heating Energy Consumption. The
adjusted daily water heating energy consumption, Qda,
takes into account that the temperature difference between the
storage tank and surrounding ambient air may not be the nominal
value of 67.5 deg.F (135 deg.F-67.5 deg.F) or 37.5 deg.C
(57.2 deg.C-19.7 deg.C) due to the 10 deg.F (5.6 deg.C) allowable
variation in storage tank temperature, 135 deg.F
5 deg.F (57.2 deg.C 2.8 deg.C), and the 5 deg.F
(2.8 deg.C) allowable variation in surrounding ambient temperature
65 deg.F (18.3 deg.C) to 70 deg.F (21.1 deg.C). The adjusted daily
water heating energy consumption is computed as:
Qda = QD - [(Tstby, 2 -
Ta, stby,2) - (135 deg.F - 67.5 deg.F)]
UAstby, 2
or Qda = QD - [(Tstby, 2
- Ta, stby, 2) - (57.2 deg.C - 19.7 deg.C)]
UAstby, 2
Where:
Qda = the adjusted daily water heating energy
consumption, Btu (kJ).
Qd = as defined in section 6.1.5.
Tstby, 2 = the mean tank temperature during the total
standby portion, stby, 2, of the 24-hour test,
deg.F ( deg.C).
Ta, stby, 2 = the average ambient temperature during the
total standby portion, stby, 2, of the 24-
hour test, deg.F ( deg.C).
UA = as defined in section 6.1.4.
stby, 2 = the number of hours during the 24-hour
simulated test when water is not being withdrawn from the water
heater.
A modification is also needed to take into account that the
temperature difference between the outlet water temperature and
supply water temperature may not be equivalent to the nominal value
of 77 deg.F
[[Page 26015]]
(135 deg.F-58 deg.F) or 42.8 deg.C (57.2 deg.C-14.4 deg.C). The
following equations adjust the experimental data to a nominal
77 deg.F (42.8 deg.C) temperature rise.
The energy used to heat water, Btu/day (kJ/day), may be computed
as:
[GRAPHIC] [TIFF OMITTED] TR11MY98.011
Where:
Mi = the mass withdrawn for the ith draw (i = 1 to 6), lb
(kg).
Cpi = the specific heat of the water of the ith draw,
Btu/lb deg.F (kJ/kg deg.C).
Tdel, i = the average water outlet temperature measured
during the ith draw (i=1 to 6), deg.F ( deg.C).
Tin, i = the average water inlet temperature measured
during the ith draw (i=1 to 6), deg.F ( deg.C).
r = as defined in section 6.1.3.
The energy required to heat the same quantity of water over a
77 deg.F (42.8 deg.C) temperature rise, Btu/day (kJ/day), is:
[GRAPHIC] [TIFF OMITTED] TR11MY98.012
The difference between these two values is:
QHWD = QHW, 77+-F -QHW
or QHWD = QHW,42.8+-F -QHW
which must be added to the adjusted daily water heating energy
consumption value. Thus, the daily energy consumption value which
takes into account that the temperature difference between the
storage tank and ambient temperature may not be 67.5 deg.F
(37.5 deg.C) and that the temperature rise across the storage tank
may not be 77 deg.F (42.8 deg.C) is:
Qdm = Qda + QHWD
6.1.7 Energy Factor. The energy factor, Ef, is computed as:
[GRAPHIC] [TIFF OMITTED] TR11MY98.013
or
[GRAPHIC] [TIFF OMITTED] TR11MY98.014
Where:
Qdm = the modified daily water heating energy consumption
as computed in accordance with section 6.1.6, Btu (kJ).
Mi = the mass withdrawn for the ith draw (i = 1 to 6), lb
(kg).
Cpi = the specific heat of the water of the ith draw,
Btu/lb deg.F (kJ/kg deg.C).
6.1.8 Annual Energy Consumption. The annual energy consumption
for storage-type and heat pump water heaters is computed as:
Eannual = 365 x Qdm
Where:
Qdm = the modified daily water heating energy consumption
as computed in accordance with section 6.1.6, Btu (kJ).
365 = the number of days in a year.
6.2 Instantaneous Water Heaters.
6.2.1 Maximum GPM (L/min) Rating Computation. Compute the
maximum gpm (L/min) rating as:
[GRAPHIC] [TIFF OMITTED] TR11MY98.015
which may be expressed as:
[GRAPHIC] [TIFF OMITTED] TR11MY98.016
Where:
M10m = the mass of water collected during the 10-minute
test, lb (kg).
Tdel = the average delivery temperature, deg.F ( deg.C).
Tin = the average inlet temperature, deg.F ( deg.C).
= the density of water at the average delivery
temperature, lb/gal (kg/L).
If a water meter is used the maximum gpm (L/min) rating is
computed as:
[GRAPHIC] [TIFF OMITTED] TR11MY98.017
Where:
V10m = the volume of water measured during the 10-minute
test, gal (L).
Tdel = as defined in this section.
Tin = as defined in this section.
6.2.2 Recovery Efficiency
6.2.2.1 Fixed Input Instantaneous Water Heaters. The recovery
efficiency is computed as:
[GRAPHIC] [TIFF OMITTED] TR11MY98.018
Where:
M1 = total mass removed during the first draw of the 24-
hour simulated use test, lb (kg), or, if the volume of water is
being measured,
M1 = V1 .
Where:
V1 = total volume removed during the first draw of the
24-hour simulated use test, gal (L).
= density of the water at the water temperature measured at
the point where the flow volume is measured, lb/gal (kg/L).
Cp1 = specific heat of the withdrawn water,
(Tdel,1 + Tin,1) / 2, Btu/lb deg.F (kJ/kg
deg.C).
Tdel, 1 = average water outlet temperature measured
during the first draw of the 24-hour simulated use test, deg.F
( deg.C).
Tin, 1 = average water inlet temperature measured during
the first draw of the 24-hour simulated use test, deg.F ( deg.C).
Qr = the total energy used by the water heater between
cut-out prior to the first draw and cut-out following the first
draw, including auxiliary energy such as pilot lights, pumps, fans,
etc., Btu (kJ). (Electrical auxiliary energy shall be converted to
thermal energy using the following conversion: 1 kWh = 3,412 Btu.)
6.2.2.2 Variable Input Instantaneous Water Heaters. For
instantaneous water heaters that have a variable firing rate, two
recovery efficiency values are computed, one at the maximum input
rate and one at the minimum input rate. The recovery efficiency used
in subsequent computations is taken as the average of these two
values. The maximum recovery efficiency is computed as:
[GRAPHIC] [TIFF OMITTED] TR11MY98.019
Where:
M1 = as defined in section 6.2.2.1.
Cp1 = as defined in section 6.2.2.1.
Tdel, 1 = as defined in section 6.2.2.1.
Tin, 1 = as defined in section 6.2.2.1.
Qr, max = the total energy used by the water heater
between burner cut-out prior to the first draw and burner cut-out
following the first draw, including auxiliary energy such as pilot
lights, Btu (kJ).
The minimum recovery efficiency is computed as:
[GRAPHIC] [TIFF OMITTED] TR11MY98.020
Where:
M4 = the mass withdrawn during the fourth draw, lb (kg),
or, if the volume of water is being measured,
M4 = V4
Where:
V4 = total volume removed during the first draw of the
24-hour simulated use test, gal (L).
= as defined in 6.2.2.1
Cp4 = the specific heat of water, Btu/lb deg.F (kJ/kg
deg.C).
Tdel, 4 = the average delivery temperature for the fourth
draw, deg.F ( deg.C).
Tin, 4 = the average inlet temperature for the fourth
draw, deg.F ( deg.C).
Qr, min = the total energy consumed between the beginning
of the fourth draw and burner cut-out following the fourth draw,
including auxiliary energy such as pilot lights, Btu (kJ).
The recovery efficiency is computed as:
[[Page 26016]]
[GRAPHIC] [TIFF OMITTED] TR11MY98.021
Where:
r,max = as calculated above.
r,min = as calculated above.
6.2.3 Daily Water Heating Energy Consumption. The daily water
heating energy consumption, Qd, is computed as:
Qd = Q
Where:
Q = the energy used by the instantaneous water heater during the 24-
hr simulated use test.
A modification is needed to take into account that the
temperature difference between the outlet water temperature and
supply water temperature may not be equivalent to the nominal value
of 77 deg.F (135 deg.F-58 deg.F) or 42.8 deg.C
(57.2 deg.C-14.4 deg.C). The following equations adjust the
experimental data to a nominal 77 deg.F (42.8 deg.C) temperature
rise.
The energy used to heat water may be computed as:
[GRAPHIC] [TIFF OMITTED] TR11MY98.022
Where:
Mi = the mass withdrawn during the ith draw, lb (kg).
Cpi = the specific heat of water of the ith draw, Btu/
lb deg.F (kJ/kg ( deg.C).
Tdel,i = the average delivery temperature of the ith
draw, deg.F ( deg.C).
Tin,i = the average inlet temperature of the ith draw,
deg.F ( deg.C).
r = as calculated in section 6.2.2.2.
The energy required to heat the same quantity of water over a
77 deg.F (42.8 deg.C) temperature rise is:
[GRAPHIC] [TIFF OMITTED] TR11MY98.023
Where:
Mi = the mass withdrawn during the ith draw, lb (kg).
Cpi = the specific heat of water of the ith draw, Btu/
lb deg.F (kJ/kg ( deg.C).
r = as calculated above.
The difference between these two values is:
QHWD = QHW, 77 deg.F - QHW
or QHWD = QHW, 42.8 deg.C -
QHW
which much be added to the daily water heating energy
consumption value. Thus, the daily energy consumption value which
takes into account that the temperature rise across the storage tank
may not be 77 deg.F (42.8 deg.C) is:
Qdm = Qd + QHWD
6.2.4 Energy Factor. The energy factor, Ef, is
computed as:
[GRAPHIC] [TIFF OMITTED] TR11MY98.024
Where:
Qdm = the daily water heating energy consumption as
computed in accordance with section 6.2.3, Btu (kJ).
Mi = the mass associated with the ith draw, lb (kg).
Cpi = the specific heat of water computed at a
temperature of (58 deg.F + 135 deg.F) / 2, Btu/lb deg.F
[(14.4 deg.C + 57.2 deg.C) / 2, kJ/kg deg.C].
6.2.5 Annual Energy Consumption. The annual energy consumption
for instantaneous type water heaters is computed as:
Eannual = 365 x Qdm
Where:
Qdm = the modified daily energy consumption, Btu/day (kJ/
day).
365 = the number of days in a year.
7. Ratings for Untested Models
In order to relieve the test burden on manufacturers who offer
water heaters which differ only in fuel type or power input, ratings
for untested models may be established in accordance with the
following procedures. In lieu of the following procedures a
manufacturer may elect to test the unit for which a rating is
sought.
7.1 Gas Water Heaters. Ratings obtained for gas water heaters
using natural gas can be used for an identical water heater which
utilizes propane gas if the input ratings are within
10%.
7.2 Electric Water Heaters
7.2.1 First-Hour Rating. If an electric storage-type water
heater is available with more than one input rating, the
manufacturer shall designate the standard input rating, and the
water heater need only be tested with heating elements at the
designated standard input ratings. The first-hour ratings for units
having power input rating less than the designated standard input
rating shall be assigned a first-hour rating equivalent to the first
draw of the first-hour rating for the electric water heater with the
standard input rating. For units having power inputs greater than
the designated standard input rating, the first-hour rating shall be
equivalent to that measured for the water heater with the standard
input rating.
7.2.2 Energy Factor. The energy factor for identical electric
storage-type water heaters, with the exception of heating element
wattage, may use the energy factor obtained during testing of the
water heater with the designated standard input rating.
[FR Doc. 98-12296 Filed 5-8-98; 8:45 am]
BILLING CODE 6450-01-P
