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Proposed Rule2021-27004

Energy Conservation Program: Test Procedure for Consumer Water Heaters and Residential-Duty Commercial Water Heaters

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Published

January 11, 2022

Issuing agencies

Energy Department

Abstract

The U.S. Department of Energy (DOE) proposes to amend the test procedure for consumer water heaters and residential-duty commercial water heaters to update the procedure to the latest versions of the industry standards that are incorporated by reference and to consider procedures that are included in a draft industry standard, which is not currently incorporated by reference. DOE also proposes to interpret the statutory definition of consumer water heater to cover larger capacity heat pump type units as commercial equipment and proposes several new definitions for water heaters that cannot be appropriately tested with the current DOE test procedure, along with test methods to test these products. DOE is seeking comment from interested parties on the proposals.

Full Text

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<title>Federal Register, Volume 87 Issue 7 (Tuesday, January 11, 2022)</title>
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[Federal Register Volume 87, Number 7 (Tuesday, January 11, 2022)]
[Proposed Rules]
[Pages 1554-1614]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2021-27004]

[[Page 1553]]

Vol. 87

Tuesday,

No. 7

January 11, 2022

Part IV

Department of Energy

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10 CFR Parts 429, 430, and 431

Energy Conservation Program: Test Procedure for Consumer Water Heaters
and Residential-Duty Commercial Water Heaters; Proposed Rule

Federal Register / Vol. 87 , No. 7 / Tuesday, January 11, 2022 /
Proposed Rules

[[Page 1554]]

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DEPARTMENT OF ENERGY

10 CFR Parts 429, 430, and 431

[EERE-2019-BT-TP-0032]
RIN 1904-AE77

Energy Conservation Program: Test Procedure for Consumer Water
Heaters and Residential-Duty Commercial Water Heaters

AGENCY: Office of Energy Efficiency and Renewable Energy, Department of
Energy.

ACTION: Notice of proposed rulemaking and request for comment.

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SUMMARY: The U.S. Department of Energy (DOE) proposes to amend the test
procedure for consumer water heaters and residential-duty commercial
water heaters to update the procedure to the latest versions of the
industry standards that are incorporated by reference and to consider
procedures that are included in a draft industry standard, which is not
currently incorporated by reference. DOE also proposes to interpret the
statutory definition of consumer water heater to cover larger capacity
heat pump type units as commercial equipment and proposes several new
definitions for water heaters that cannot be appropriately tested with
the current DOE test procedure, along with test methods to test these
products. DOE is seeking comment from interested parties on the
proposals.

DATES:
Comments: DOE will accept comments, data, and information regarding
this notice of proposed rulemaking (NOPR) on or before March 14, 2022.
See section V, ``Public Participation,'' for details.
Meeting: DOE will hold a webinar on Tuesday, January 25, 2022, from
1:00 p.m. to 5:00 p.m. See section V, ``Public Participation,'' for
webinar registration information, participant instructions, and
information about the capabilities available to webinar participants.

ADDRESSES: Interested persons are encouraged to submit comments using
the Federal eRulemaking Portal at <a href="http://www.regulations.gov">www.regulations.gov</a>. Follow the
instructions for submitting comments. Alternatively, interested persons
may submit comments, identified by docket number EERE-2019-BT-TP-0032,
by any of the following methods:
1. Federal eRulemaking Portal: <a href="http://www.regulations.gov">www.regulations.gov</a>. Follow the
instructions for submitting comments.
2. Email to: <a href="/cdn-cgi/l/email-protection#0e596f7a6b7c466b6f7a6b7c7d3c3e3f375a5e3e3e3d3c4e6b6b206a616b20696178">[email&#160;protected]</a>. Include the docket
number EERE-2019-BT-TP-0032 in the subject line of the message.
No telefacsimilies (faxes) will be accepted. For detailed
instructions on submitting comments and additional information on this
process, see section V of this document.
Although DOE has routinely accepted public comment submissions
through a variety of mechanisms, including postal mail and hand
delivery/courier, the Department has found it necessary to make
temporary modifications to the comment submission process in light of
the ongoing COVID-19 pandemic. DOE is currently suspending receipt of
public comments via postal mail and hand delivery/courier, and instead,
the Department is only accepting electronic submissions at this time.
If a commenter finds that this change poses an undue hardship, please
contact Appliance Standards Program staff at (202) 586-1445 to discuss
the need for alternative arrangements. Once the COVID-19 pandemic
health emergency is resolved, DOE anticipates resuming all of its
regular options for public comment submission, including postal mail
and hand delivery/courier.
Docket: The docket, which includes Federal Register notices, public
meeting attendee lists and transcripts (if a public meeting is held),
comments, and other supporting documents/materials, is available for
review at <a href="http://www.regulations.gov">www.regulations.gov</a>. All documents in the docket are listed
in the <a href="http://www.regulations.gov">www.regulations.gov</a> index. However, some documents listed in the
index, such as those containing information that is exempt from public
disclosure, may not be publicly available.
The docket web page can be found at <a href="http://www.regulations.gov/docket?D=EERE-2019-BT-TP-0032">www.regulations.gov/docket?D=EERE-2019-BT-TP-0032</a>. The docket web page contains
instructions on how to access all documents, including public comments,
in the docket. See section V for information on how to submit comments
through <a href="http://www.regulations.gov">www.regulations.gov</a>.

FOR FURTHER INFORMATION CONTACT:
Ms. Julia Hegarty, U.S. Department of Energy, Office of Energy
Efficiency and Renewable Energy, Building Technologies Office, EE-5B,
1000 Independence Avenue SW, Washington, DC 20585-0121. Telephone:
(202) 597-6737. Email <a href="/cdn-cgi/l/email-protection#7d3c0d0d11141c131e182e091c13191c0f190e2c08180e091412130e3d181853191218531a120b">[email&#160;protected]</a>.
Ms. Kristin Koernig, U.S. Department of Energy, Office of the
General Counsel, GC-33, 1000 Independence Avenue SW, Washington, DC
20585-0121. Telephone: (202) 586-3593. Email:
<a href="/cdn-cgi/l/email-protection#c4afb6adb7b0adaaeaafaba1b6aaada384acb5eaa0aba1eaa3abb2">[email&#160;protected]</a>.
For further information on how to submit a comment, review other
public comments and the docket, or participate in a public meeting (if
one is held), contact the Appliance and Equipment Standards Program
staff at (202) 287-1445 or by email:
<a href="/cdn-cgi/l/email-protection#fdbc8d8d91949c939e98ae899c93999c8f998eac88988e899492938ebd9898d3999298d39a928b">[email&#160;protected]</a>.

SUPPLEMENTARY INFORMATION: DOE proposes to incorporate by reference the
following industry standards into part 430:
American Society of Heating, Refrigerating, and Air-Conditioning
Engineers (ASHRAE) Standard 41.1-2020, (ASHRAE 41.1-2020), ``Standard
Methods for Temperature Measurement,'' approved June 30, 2020.
American National Standards Institute (ANSI)/ASHRAE Standard 41.6-
2014, (ASHRAE 41.6-2014), ``Standard Method for Humidity Measurement,''
ANSI approved July 3, 2014.
Copies of ASHRAE 41.1-2020 and ASHRAE 41.6-2014 can be obtained
from the American Society of Heating, Refrigerating, and Air-
Conditioning Engineers, Inc., 1791 Tullie Circle NE, Atlanta, GA 30329,
(800) 527-4723 or (404) 636-8400, or online at: <a href="http://www.ashrae.org">www.ashrae.org</a>.
American Society for Testing and Materials International (ASTM)
Standard D2156-09 (Reapproved 2018) (ASTM D2156-09 (RA 2018)),
``Standard Test Method for Smoke Density in Flue Gases from Burning
Distillate Fuels,'' reapproved October 1, 2018.
ASTM Standard E97-1987 (ASTM E97-1987 (W1991)), ``Standard Test
Methods for Directional Reflectance Factor, 45-Deg 0-Deg, of Opaque
Specimens by Broad-Band Filter Reflectometry,'' approved January 1987,
withdrawn 1991.
Copies of ASTM D2156-09 (RA 2018) and ASTM E97-1987 (W1991) can be
obtained from the American Society for Testing and Materials
International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken,
PA 19428-2959 or online at: <a href="http://www.astm.org">www.astm.org</a>.
See section IV.M of this document for a further discussion of these
industry standards.

Table of Contents

I. Authority and Background
A. Authority
B. Background
II. Synopsis of the Notice of Proposed Rulemaking
III. Discussion
A. Scope of Applicability
1. Definitions
B. Updates to Industry Standards

[[Page 1555]]

1. ASHRAE 41.1
2. ASHRAE 118.2
C. Test Procedure Requirements
1. Commercial Water Heater Draw Pattern
2. Terminology
3. Test Conditions
4. Mixing Valve
5. Mass Measurements
6. Very Small Draw Pattern Flow Rate
7. Low Temperature Water Heaters
8. Heat Pump Water Heater Heaters
9. Circulating Gas-Fired Water Heaters
10. Solar Water Heaters
11. Connected Water Heaters
12. Drain Down Test Method
13. Alternate Order 24-Hour Simulated-Use Test
14. Untested Provisions
D. Reporting
E. Test Procedure Costs and Harmonization
1. Test Procedure Costs and Impact
2. Harmonization With Industry Standards
F. Compliance Date and Waivers
IV. Procedural Issues and Regulatory Review
A. Review Under Executive Order 12866
B. Review Under the Regulatory Flexibility Act
1. Description of Reasons Why Action Is Being Considered
2. Objectives of, and Legal Basis for, Rule
3. Description and Estimate of Small Entities Regulated
4. Description and Estimate of Compliance Requirements
5. Duplication, Overlap, and Conflict With Other Rules and
Regulations
6. Significant Alternatives to the Rule
C. Review Under the Paperwork Reduction Act of 1995
D. Review Under the National Environmental Policy Act of 1969
E. Review Under Executive Order 13132
F. Review Under Executive Order 12988
G. Review Under the Unfunded Mandates Reform Act of 1995
H. Review Under the Treasury and General Government
Appropriations Act, 1999
I. Review Under Executive Order 12630
J. Review Under Treasury and General Government Appropriations
Act, 2001
K. Review Under Executive Order 13211
L. Review Under Section 32 of the Federal Energy Administration
Act of 1974
M. Description of Materials Incorporated by Reference
V. Public Participation
A. Participation in the Webinar
B. Submission of Comments
VI. Approval of the Office of the Secretary

I. Authority and Background

Consumer water heaters are included in the list of ``covered
products'' for which DOE is authorized to establish and amend energy
conservation standards and test procedures. (42 U.S.C. 6292(a)(4))
DOE's energy conservation standards and test procedure for consumer
water heaters are currently prescribed at Title 10 of the Code of
Federal Regulations (CFR), part 430, section 32(d), and 10 CFR part
430, subpart B, appendix E (appendix E). As discussed in this NOPR,
residential-duty commercial water heaters, for which DOE is also
authorized to establish and amend energy conservation standards and
test procedures (42 U.S.C. 6311(1)(K)), must also be tested according
to appendix E. 10 CFR 431.106(b)(1) (See 42 U.S.C. 6295(e)(5)(H)).
DOE's energy conservation standards for residential-duty commercial
water heaters are currently prescribed at 10 CFR 431.110(b)(1). The
following sections discuss DOE's authority to establish and amend test
procedures for consumer water heaters and residential-duty commercial
water heaters, as well as relevant background information regarding
DOE's consideration of test procedures for these products and
equipment.

A. Authority

The Energy Policy and Conservation Act, as amended (EPCA),\1\
authorizes DOE to regulate the energy efficiency of a number of
consumer products and certain industrial equipment. (42 U.S.C. 6291-
6317, as codified) Title III, Part B \2\ of EPCA established the Energy
Conservation Program for Consumer Products Other Than Automobiles,
which sets forth a variety of provisions designed to improve energy
efficiency. (42 U.S.C. 6291-6309, as codified) These products include
consumer water heaters, the subject of this document. (42 U.S.C.
6292(a)(4)) Title III, Part C \3\ of EPCA, added by Public Law 95-619,
Title IV, section 441(a), established the Energy Conservation Program
for Certain Industrial Equipment, which again sets forth a variety of
provisions designed to improve energy efficiency. (42 U.S.C. 6311-6317,
as codified) This equipment includes commercial water heaters, which
are also the subject of this document. (42 U.S.C. 6311(1)(k))
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\1\ All references to EPCA in this document refer to the statute
as amended through Energy Act of 2020, Public Law 116-260 (Dec. 27,
2020).
\2\ For editorial reasons, upon codification in the U.S. Code,
Part B was redesignated Part A.
\3\ For editorial reasons, upon codification in the U.S. Code,
Part C was redesignated Part A-1.
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The energy conservation program under EPCA consists essentially of
four parts: (1) Testing, (2) labeling, (3) the establishment of Federal
energy conservation standards, and (4) certification and enforcement
procedures. Relevant provisions of EPCA specifically include
definitions (42 U.S.C. 6291; 42 U.S.C. 6311), test procedures (42
U.S.C. 6293; 42 U.S.C. 6314), labeling provisions (42 U.S.C. 6294; 42
U.S.C. 6315), energy conservation standards (42 U.S.C. 6295; 42 U.S.C.
6313), and the authority to require information and reports from
manufacturers (42 U.S.C. 6296; 42 U.S.C. 6316).
The Federal testing requirements consist of test procedures that
manufacturers of covered products and commercial equipment must use as
the basis for: (1) Certifying to DOE that their products comply with
the applicable energy conservation standards adopted pursuant to EPCA
(42 U.S.C. 6295(s); 42 U.S.C. 6296; 42 U.S.C. 6316(a)-(b)), and (2)
making representations about the efficiency of those products (42
U.S.C. 6293(c); 42 U.S.C. 6314(d)). Similarly, DOE must use these test
procedures to determine whether the products comply with relevant
standards promulgated under EPCA. (42 U.S.C. 6295(s))
Federal energy efficiency requirements for covered products and
covered equipment established under EPCA generally supersede State laws
and regulations concerning energy conservation testing, labeling, and
standards. (42 U.S.C. 6297(a)-(c); 42 U.S.C. 6316(a)-(b)) However, DOE
may grant waivers of Federal preemption in limited circumstances for
particular State laws or regulations, in accordance with the procedures
and other provisions of EPCA. (42 U.S.C. 6297(d); 42 U.S.C. 6316(a); 42
U.S.C. 6316(b)(2)(D))
Under 42 U.S.C. 6293, the statute sets forth the criteria and
procedures DOE must follow when prescribing or amending test procedures
for covered products. Specifically, EPCA requires that any test
procedures prescribed or amended shall be reasonably designed to
produce test results which measure energy efficiency, energy use, or
estimated annual operating cost of a covered product during a
representative average use cycle or period of use and shall not be
unduly burdensome to conduct. (42 U.S.C. 6293(b)(3)) Under 42 U.S.C.
6314, the statute sets forth the criteria and procedures DOE must
follow when prescribing or amending test procedures for covered
equipment, reciting similar requirements at 42 U.S.C. 6314(a)(2).
In addition, the Energy Independence and Security Act of 2007 (EISA
2007) amended EPCA to require that DOE amend its test procedures for
all covered consumer products to integrate measures of standby mode and
off mode energy consumption. (42 U.S.C. 6295(gg)(2)(A)) Standby mode
and off mode energy consumption must be incorporated into the overall
energy efficiency, energy consumption, or other energy descriptor for
each covered product unless the current test procedures already account
for and incorporate standby and off mode energy consumption or such
integration

[[Page 1556]]

is technically infeasible. (42 U.S.C. 6295(gg)(2)(A)(i)-(ii)) If an
integrated test procedure is technically infeasible, DOE must prescribe
a separate standby mode and off mode energy use test procedure for the
covered product, if technically feasible. (42 U.S.C.
6295(gg)(2)(A)(ii)) Any such amendment must consider the most current
versions of the International Electrotechnical Commission (IEC)
Standard 62301 \4\ and IEC Standard 62087,\5\ as applicable. (42 U.S.C.
6295(gg)(2)(A))
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\4\ IEC 62301, Household electrical appliances--Measurement of
standby power (Edition 2.0, 2011-01).
\5\ IEC 62087, Methods of measurement for the power consumption
of audio, video, and related equipment (Edition 3.0, 2011-04).
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The American Energy Manufacturing Technical Corrections Act
(AEMTCA), Public Law 112-210, further amended EPCA to require that DOE
establish a uniform efficiency descriptor and accompanying test methods
to replace the energy factor (EF) metric for covered consumer water
heaters and the thermal efficiency (TE) and standby loss (SL) metrics
for commercial water-heating equipment \6\ within one year of the
enactment of AEMTCA. (42 U.S.C. 6295(e)(5)(B)-(C)) The uniform
efficiency descriptor and accompanying test method were required to
apply, to the maximum extent practicable, to all water-heating
technologies in use at the time and to future water-heating
technologies, but could exclude specific categories of covered water
heaters that do not have residential uses, can be clearly described,
and are effectively rated using the TE and SL descriptors. (42 U.S.C.
6295(e)(5)(F) and (H)) In addition, beginning one year after the date
of publication of DOE's final rule establishing the uniform descriptor,
the efficiency standards for covered water heaters were required to be
denominated according to the uniform efficiency descriptor established
in the final rule (42 U.S.C. 6295(e)(5)(D)); and for affected covered
water heaters tested prior to the effective date of the test procedure
final rule, DOE was required to develop a mathematical factor for
converting the measurement of their energy efficiency from the EF, TE,
and SL metrics to the new uniform energy descriptor. (42 U.S.C.
6295(e)(5)(E)(i)-(ii))
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\6\ The initial thermal efficiency and standby loss test
procedures for commercial water heating equipment (including
residential-duty commercial water heaters) were added to EPCA by the
Energy Policy Act of 1992 (EPACT 1992), Public Law 102-486, and
corresponded to those referenced in the ASHRAE and Illuminating
Engineering Society of North America (IESNA) Standard 90.1-1989
(i.e., ASHRAE Standard 90.1-1989). (42 U.S.C. 6314(a)(4)(A)) DOE
subsequently updated the commercial water heating equipment test
procedures on two separate occasions--once in a direct final rule
published on October 21, 2004, and again in a final rule published
on May 16, 2012. These rules incorporated by reference certain
sections of the latest versions of ANSI Standard Z21.10.3, Gas Water
Heaters, Volume III, Storage Water Heaters with Input Ratings Above
75,000 Btu Per Hour, Circulating and Instantaneous, available at the
time (i.e., ANSI Z21.10.3-1998 and ANSI Z21.10.3-2011,
respectively). 69 FR 61974, 61983 (Oct. 21, 2004) and 77 FR 28928,
28996 (May 16, 2012).
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EPCA also requires that, at least once every 7 years, DOE evaluate
test procedures for each type of covered product and covered equipment,
including consumer water heaters and commercial water heaters that are
the subject of this document, to determine whether amended test
procedures would more accurately or fully comply with the requirements
for the test procedures to not be unduly burdensome to conduct and be
reasonably designed to produce test results that reflect energy
efficiency, energy use, and estimated operating costs during a
representative average use cycle (or additionally, period of use for
consumer products). (42 U.S.C. 6293(b)(1)(A); 6314(a)(1))
If the Secretary determines, on her own behalf or in response to a
petition by any interested person, that a test procedure should be
prescribed or amended, the Secretary shall promptly publish in the
Federal Register proposed test procedures and afford interested persons
an opportunity to present oral and written data, views, and arguments
with respect to such procedures. (42 U.S.C. 6293(b)(2); 42 U.S.C.
6314(b)) The comment period on a proposed rule to amend a test
procedure shall be at least 60 days \7\ and may not exceed 270 days.
(42 U.S.C. 6293(b)(2)) In prescribing or amending a test procedure, the
Secretary shall take into account such information as the Secretary
determines relevant to such procedure, including technological
developments relating to energy use or energy efficiency of the type
(or class) of covered products involved. (42 U.S.C. 6293(b)(2)). If DOE
determines that test procedure revisions are not appropriate, DOE must
publish in the Federal Register its determination not to amend the test
procedures. (42 U.S.C. 6293(b)(1)(A)(ii); 42 U.S.C. 6314(a)(1)(A)(ii))
DOE is publishing this NOPR in satisfaction of the 7-year review
requirement specified in EPCA.
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\7\ For covered equipment, if the Secretary determines that a
test procedure amendment is warranted, the Secretary must publish
proposed test procedures in the Federal Register, and afford
interested persons an opportunity (of not less than 45 days'
duration) to present oral and written data, views, and arguments on
the proposed test procedures. (42 U.S.C. 6314(b))
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B. Background

As stated previously in this document, DOE's current test procedure
for consumer water heaters appears at appendix E.
Pursuant to the requirements of the AEMTCA amendments to EPCA
discussed previously, DOE updated the consumer water heater test
procedure through a final rule published on July 11, 2014 (July 2014
final rule). 79 FR 40542. The July 2014 final rule: Established a
uniform energy descriptor (i.e., uniform energy factor (UEF)) for all
consumer water heaters and for commercial water heaters with consumer
applications (i.e., those commercial water heaters that met the newly
established definition of a ``residential-duty commercial water
heater''); extended coverage to eliminate certain gaps in the previous
version of the consumer water heater test procedure, including small-
volume storage water heaters (i.e., with storage volumes between 2 and
20 gallons), large volume water heaters (i.e., greater than 100 gallons
for gas-fired and oil-fired storage water heaters and greater than 120
gallons for electric storage water heaters), and electric instantaneous
water heaters; updated the draw pattern from a single 24-hour
simulated-use test draw pattern to include several different draw
patterns that vary depending on equipment capacity as measured by the
first-hour rating (FHR) or maximum gallons per minute (Max GPM) test;
and updated the outlet water temperature test condition requirement. 79
FR 40542, 40545, 40548, 40551-40554 (July 11, 2014).
As indicated, the uniform energy descriptor and the consumer water
heater test procedure apply to ``residential-duty commercial water
heaters,'' which were initially defined in the July 2014 final rule and
include commercial water heaters with consumer applications. Id. at 79
FR 40586; 10 CFR 431.106(b)(1) and 10 CFR 431.110(b). DOE later amended
the definition of a ``residential-duty commercial water heater'' in a
final rule published on November 10, 2016 (November 2016 final rule),
to define such equipment as any gas-fired storage, oil-fired storage,
or electric instantaneous commercial water heater that meets the
following conditions: (1) For models requiring electricity, uses
single-phase external power supply; (2) Is not designed to provide
outlet hot water at temperatures greater than

[[Page 1557]]

180 [deg]F; and (3) Does not meet any of the following criteria:

------------------------------------------------------------------------
Indicator of non-residential
Water heater type application
------------------------------------------------------------------------
Gas-fired Storage...................... Rated input >105 kBtu/h; Rated
storage volume >120 gallons.
Oil-fired Storage...................... Rated input >140 kBtu/h; Rated
storage volume >120 gallons.
Electric Instantaneous................. Rated input >58.6 kW; Rated
storage volume >2 gallons.
------------------------------------------------------------------------

81 FR 79261, 79321-79322; 10 CFR 431.102.

In the November 2016 final rule DOE also, in relevant part, revised
some of the definitions for consumer water heater product classes and
removed others. Definitions for both ``electric heat pump water
heater'' and ``gas-fired heat pump water heater'' were removed, and
revisions were made to the definitions of ``electric storage water
heater'' and ``gas-fired storage water heater,'' which made each
sufficiently broad to cover electric heat pump water heaters and gas-
fired heat pump water heaters, respectively. 81 FR 79261, 79320-79321
(Nov. 10, 2016). The November 2016 final rule also amended the
definitions of ``electric instantaneous water heater'', ``gas-fired
instantaneous water heater'', ``oil-fired instantaneous water heater'',
and ``oil-fired storage water heater.'' Id.
On December 29, 2016, DOE published a final rule (December 2016
final rule) that denominated the efficiency standards for consumer
water heaters and residential-duty commercial water heaters in terms of
the uniform efficiency descriptor (i.e., the UEF metric) and
established mathematical conversion factors to translate the EF, TE,
and SL metrics to the UEF metric. 81 FR 96204. The published conversion
factors were applicable for converting test results for a period of one
year after the publication of the December 2016 final rule as required
by EPCA, as amended by AEMTCA. 42 U.S.C. 6295(e)(5)(E)(v)(II); 81 FR
96204, 96208 (Dec. 29, 2016). The conversion factors translating
previously tested EF, TE, and SL values to converted UEF values were
removed from 10 CFR 429.17 on December 29, 2017, at which time all
rated UEF values were to be based on actual testing to the test
procedure published in the July 2014 final rule (i.e., to the UEF test
procedure). 81 FR 96204, 96235.
Most recently, on April 16, 2020, DOE published in the Federal
Register a request for information (April 2020 RFI) seeking comments on
the existing DOE test procedure for consumer water heaters and
residential-duty commercial water heaters. 85 FR 21104. The April 2020
RFI discussed a draft version of the ANSI/ASHRAE Standard 118.2, which
was published in March 2019 (March 2019 ASHRAE Draft 118.2), which is
very similar to the existing DOE test procedure of consumer water
heaters and residential-duty commercial water heaters. 85 FR 21104,
21108-21110 (April 16, 2020).
In the April 2020 RFI, DOE requested comments, information, and
data about a number of issues, including: (1) Differences between the
March 2019 ASHRAE Draft 118.2 and the existing DOE test procedure; (2)
test tolerances for supply water temperature, ambient temperature,
relative humidity, voltage, and gas pressure; (3) the location of the
instrumentation that measures water volume or mass; and (4) how to test
certain types of consumer water heaters that cannot be easily tested to
the existing DOE test procedure (i.e., recirculating gas-fired
instantaneous water heaters, water heaters that cannot deliver water at
125 [deg]F <plus-minus>5 [deg]F, and water heaters with storage volumes
greater than 2 gallons that cannot have their internal tank
temperatures measured). Id. at 85 FR 21109-21114.
DOE received comments in response to the April 2020 RFI from the
interested parties listed in Table I.1.

Table I.1--List of Commenters With Written Submissions in Response to the April 2020 RFI
----------------------------------------------------------------------------------------------------------------
Commenter(s) Reference in this NOPR Commenter type *
----------------------------------------------------------------------------------------------------------------
A.O. Smith Corporation.................... A.O. SMITH........................... M.
Air-Conditioning, Heating, and AHRI................................. TA.
Refrigeration Institute.
American Public Gas Association........... APGA................................. TA.
Appliance Standards Awareness Project, Joint Advocates...................... AG.
American Council for an Energy-Efficient
Economy, Consumer Federation of America,
National Consumer Law Center, Natural
Resources Defense Council, and Northeast
Energy Efficiency Partnerships.
Bradford White Corporation................ BWC.................................. M.
California Energy Commission.............. CEC.................................. State.
CSA Group................................. CSA.................................. TL.
Edison Electric Institute................. EEI.................................. U.
Keltech Inc............................... Keltech.............................. M.
M C....................................... M C.................................. I.
Northwest Energy Efficiency Alliance...... NEEA................................. AG.
Pacific Gas and Electric Company, San CA IOUs.............................. U.
Diego Gas and Electric, and Southern
California Edison.
Rheem Manufacturing Company............... Rheem................................ M.
Rinnai America Corporation................ Rinnai............................... M.
Stone Mountain Technologies, Inc.......... SMTI................................. M.
----------------------------------------------------------------------------------------------------------------
* AG: Advocacy Group; State: Government Organization; I: Individual; M: Manufacturer; TA: Trade Association; TL:
Test Laboratory; U: Utility or Utility Trade Association.

[[Page 1558]]

A parenthetical reference at the end of a comment quotation or
paraphrase provides the location of the item in the public record.\8\
---------------------------------------------------------------------------

\8\ The parenthetical reference provides a reference for
information located in the docket of DOE's rulemaking to develop
test procedures for consumer water heaters and residential-duty
commercial water heaters. (Docket No. EERE-2019-BT-TP-0032, which is
maintained at: <a href="http://www.regulations.gov/docket/EERE-2019-BT-TP-0032">www.regulations.gov/docket/EERE-2019-BT-TP-0032</a>). The
references are arranged as follows: (Commenter name, comment docket
ID number, page of that document).
---------------------------------------------------------------------------

II. Synopsis of the Notice of Proposed Rulemaking

In this NOPR, DOE proposes to update appendix E, and related
sections of the CFR, as follows:

(1) Incorporate by reference current versions of industry
standards referenced by the current and proposed DOE test
procedures: ASHRAE 41.1, ASHRAE 41.6, the pending update to ASHRAE
118.2 (contingent on it being substantively the same as the current
draft under review), ASTM D2156, and ASTM E97.
(2) Add definitions for ``circulating water heater'', ``low
temperature water heater'', and ``tabletop water heater''.
(3) Specify how a mixing valve should be installed when the
water heater is designed to operate with one.
(4) Modify flow rate requirements during the FHR test for water
heaters with a rated storage volume less than 20 gallons.
(5) Modify timing of the first measurement in each draw of the
24-hour simulated-use test.
(6) Clarify the determination of the first recovery period.
(7) Clarify the mass of water to be used to calculate recovery
efficiency.
(8) Modify the terminology throughout appendix E to explicitly
state ``non-flow activated'' and ``flow-activated'' water heater,
where appropriate.
(9) Clarify the descriptions of defined measured values for the
standby period measurements.
(10) Modify the test condition specifications and tolerances,
including electric supply voltage tolerance, ambient temperature,
ambient dry bulb temperature, ambient relative humidity, standard
temperature and pressure definition, gas supply pressure, and
manifold pressure.
(11) Add provisions to address gas-fired water heaters with
measured fuel input rates that deviate from the certified input
rate.
(12) Clarify provisions for calculating the volume or mass
delivered.
(13) Add specifications for testing for the newly defined ``low
temperature water heaters''.
(14) Clarify testing requirements for the heat pump part of a
split-system heat pump water heater.
(15) Define the use of a separate unfired hot water storage tank
for testing water heaters designed to operate with a separately sold
hot water storage tank.
(16) Clarify that any connection to an external network or
control be disconnected during testing.
(17) Add procedures for estimating internal stored water
temperature for water heater designs in which the internal tank
temperature cannot be directly measured.
(18) Modify the provisions for untested water heater basic
models within 10 CFR 429.70(g) to include electric instantaneous
water heaters.

DOE's proposed actions are summarized in Table II.1 and compared to
the current test procedure; the reason for the proposed change is also
listed.

Table II.1--Summary of Changes in Proposed Test Procedure Relative to
Current Test Procedure
------------------------------------------------------------------------
Proposed test
Current DOE test procedure procedure Attribution
------------------------------------------------------------------------
References the 1986 (Reaffirmed References the Industry TP Update
2006) version of ASHRAE 41.1 updated 2020 to ASHRAE 41.1.
for methods for temperature version of ASHRAE
measurement. 41.1.
The 1982 version of ASHRAE 41.6 References the Industry TP Update
for methods for humidity 2014 version of to ASHRAE 41.6.
measurement is referenced ASHRAE 41.6,
within the 1986 version of which is
ASHRAE 41.1. referenced by
ASHRAE 41.1-2020.
References the 2009 version of References the Industry TP Update
ASTM D2156 for testing smoke version of ASTM to ASTM D2156.
density in flue gases from D2156 that was
burning distillate fuels. reaffirmed in
2018.
The 1987 version of ASTM E97 for References the Industry TP Update
testing directional reflectance 1987 version of to ASTM E97.
factor, 45-deg 0-deg, of opaque ASTM E97, which
specimens by broad-band filter is referenced by
reflectometry is referenced ASTM D2156-09
within ASTM D2156-09. (2018).
Does not define a ``circulating Adds a definition To improve the
water heater'' as used in 10 for ``circulating representativenes
CFR 430.2. water heater'' to s of the test
10 CFR 430.2. procedure.
Does not define a ``tabletop Adds a definition Reinstate
water heater'' as used as a for ``tabletop definition
product class distinction at 10 water heater'' to inadvertently
CFR 430.32(d). 10 CFR 430.2. removed by
previous final
rule.
Does not address how to Specifies how a To improve the
configure a water heater for mixing valve repeatability of
test when a mixing valve is should be the test
required for proper operation. installed when procedure.
the water heater
is designed to
operate with one.
Requires the flow rate during Requires the flow To improve the
the FHR test to be 1.0 <plus- rate during the representativenes
minus>0.25 gpm (3.8 <plus- FHR test to be s of the test
minus>0.95 L/min) for water 1.5 <plus- procedure and to
heaters with a rated storage minus>0.25 gpm align with the
volume less than 20 gallons. (3.8 <plus- industry test
minus>0.95 L/min) procedure ASHRAE
for water heaters 118.2.
with a rated
storage volume
less than 20
gallons.
Does not address the situation Clarifies that the To improve the
in which the first recovery first recovery repeatability of
ends during a draw when testing period will the test
to the 24-hour simulated-use extend to the end procedure.
test. of the draw in
which the first
recovery ended,
and that if a
second recovery
initiates prior
to the end of the
draw, that the
second recovery
is part of the
first recovery
period as well.
The recovery efficiency equation Clarifies that, To improve the
for storage-type water heaters for the repeatability of
refers to the mass of water calculation of the test
removed from the start of the recovery procedure.
test to the end of the first efficiency, the
recovery period. mass of water
removed during
the first
recovery period
includes water
removed during
all draws from
the start of the
test until the
end of the first
recovery period.

[[Page 1559]]

Appendix E uses the phrases Uses the terms Clarification.
``storage-type'' and ``non-flow
``instantaneous-type'' to refer activated'' and
to ``non-flow activated'' and ``flow-
``flow-activated'' water activated'' water
heaters, respectively. heater, where
appropriate.
The descriptions for Qsu,0, The descriptions Clarification.
Qsu,f, Tsu,0, Tsu,f, for Qsu,0, Qsu,f,
[tau]stby,1, Tt,stby,1, and Tsu,0, Tsu,f,
Ta,stby,1 only address when the [tau]stby,1,
standby period occurs between Tt,stby,1, and
draw clusters 1 and 2. Ta,stby,1 are
generalized to
refer to the
section where the
standby period is
determined.
Specifies that the first Specifies that the Reduce burden.
required measurement for each first required
draw of the 24-hour simulated- measurement for
use test is 5 seconds after the each draw of the
draw is initiated. 24-hour simulated-
use test is 15
seconds after the
draw is initiated.
Requires the electric supply Requires the Reduce burden.
voltage to be within <plus- electric supply
minus>1 percent of the rated voltage to be
voltage for the entire test. within <plus-
minus>2 percent
of the rated
voltage beginning
5 seconds after
the start of a
recovery and
ending 5 seconds
before the end of
a recovery.
Requires maintaining ambient Requires Reduce burden.
temperature for non-heat pump maintaining the
water heaters within a range of ambient
67.5 [deg]F <plus-minus>2.5 temperature for
[deg]F. non-heat pump
water heaters
within a range of
67.5 [deg]F <plus-
minus>5 [deg]F,
and with an
average of 67.5
[deg]F <plus-
minus>2.5 [deg]F.
Requires maintaining the dry Requires Reduce burden.
bulb temperature for heat pump maintaining the
water heaters within a range of dry bulb
67.5 [deg]F <plus-minus>1 temperature for
[deg]F. heat pump water
heaters within a
range of 67.5
[deg]F <plus-
minus>5 [deg]F,
and with an
average of 67.5
[deg]F <plus-
minus>1 [deg]F
during recoveries
and an average of
67.5 [deg]F <plus-
minus>2.5 [deg]F
when not
recovering.
Requires maintaining the Requires Reduce burden.
relative humidity for heat pump maintaining the
water heaters within a range of relative humidity
50 percent <plus-minus>2 for heat pump
percent. water heaters
within a range of
50 percent <plus-
minus>5 percent,
and at an average
of 50 percent
<plus-minus>2
percent during
recoveries.
Requires that the heating value States that the To improve the
be corrected to a standard standard repeatability of
temperature and pressure, but temperature is 60 the test
does not state what temperature [deg]F (15.6 procedure.
and pressure is standard or how [deg]C) and the
to correct the heating value to standard pressure
the standard temperature and is 30 inches of
pressure. mercury column
(101.6 kPa).
Provides a method
for converting
heating value
from the measured
to the standard
conditions.
Requires that the manifold Clarifies that the Reduce burden.
pressure be within <plus- manifold pressure
minus>10 percent of the tolerance applies
manufacturer recommended value. only to water
heaters with a
pressure
regulator that
can be adjusted.
Requires that the
manifold pressure
be within the
greater of <plus-
minus>10 percent
of the
manufacturer
recommended value
or <plus-
minus>0.2 inches
water column.
Does not specify the input rate Specifies that the Clarification.
at which the gas supply gas supply
pressure tolerance is pressure
determined. tolerance is to
be maintained
when operating at
the maximum input
rate.
Does not contain procedures for Adds provisions To improve the
modifying the orifice of a regarding the repeatability of
water heater that is not modification of the test
operating at the manufacturer the orifice. procedure.
specified input rate.
Does not specify how to Specifies how to To improve the
calculate the mass removed from calculate the repeatability of
the water heater when mass is mass of water the test
calculated indirectly using indirectly using procedure.
density and volume measurements. density and
volume
measurements.
Does not accommodate testing of Adds a definition To improve the
``low temperature water of ``low representativenes
heaters'' in appendix E. temperature water s and
heater'' in 10 repeatability of
CFR 430.2 and the test
requires low procedure.
temperature water
heaters to be
tested to their
maximum possible
delivery
temperature in
appendix E.
Does not explicitly define the Explicitly states To improve the
test conditions required for that the heat repeatability of
each part of a split-system pump part of a the test
heat pump water heater. split-system heat procedure.
pump water heater
is tested at the
dry bulb
temperature and
relative humidity
conditions
required for heat
pump water
heaters, and that
the storage tank
is tested at the
ambient
temperature and
relative humidity
conditions
required for non-
heat pump water
heaters.
Does not accommodate testing of Requires water To improve the
water heaters that require a heaters designed representativenes
separately-sold hot water to operate with a s of the test
storage tank to properly separately-sold procedure.
operate. hot water storage
tank to use an 80-
gallon unfired
hot water storage
tank for testing.
Does not address water heaters Explicitly states To improve the
with network connection that any repeatability of
capabilities. connection to an the test
external network procedure.
or control be
disconnected
during testing.
Does not accommodate certain Adds a ``drain To improve the
water heaters for which the down'' procedure representativenes
mean tank temperature cannot be to estimate the s of the test
directly measured. mean tank procedure.
temperature for
certain water
heaters for which
the mean tank
temperature
cannot be
directly measured.

[[Page 1560]]

10 CFR 429.70(g) does not allow Extends the Reduce burden.
untested electric instantaneous untested
water heaters to be certified, provisions within
but does allow untested 10 CFR 429.70(g)
electric storage water heaters to include
to be certified. electric
instantaneous
water heaters.
------------------------------------------------------------------------

Additionally, DOE proposes to interpret the statutory definition of
consumer water heater to exclude certain larger capacity heat pump type
units and that such units would be covered as commercial equipment.
DOE has tentatively determined that the proposed amendments
described in section III of this NOPR would not significantly affect
the measured efficiency of consumer and residential-duty commercial
water heaters. Discussion of DOE's proposed actions are addressed in
detail in section III of this NOPR.

III. Discussion

A. Scope of Applicability

This document covers those products that meet the definition of
consumer ``water heater,'' as defined in the statute at 42 U.S.C.
6291(27), as codified at 10 CFR 430.2. This document also covers
commercial water heating equipment with residential applications, i.e.,
``residential-duty commercial water heater'' (10 CFR 431.102).
1. Definitions
In the context of covered consumer products, EPCA defines ``water
heater'' as a product which utilizes oil, gas, or electricity to heat
potable water for use outside the heater upon demand, including--
(a) Storage type units which heat and store water at a
thermostatically controlled temperature, including gas storage water
heaters with an input of 75,000 Btu per hour or less, oil storage water
heaters with an input of 105,000 Btu per hour or less, and electric
storage water heaters with an input of 12 kilowatts or less;
(b) Instantaneous type units which heat water but contain no more
than one gallon of water per 4,000 Btu per hour of input, including gas
instantaneous water heaters with an input of 200,000 Btu per hour or
less, oil instantaneous water heaters with an input of 210,000 Btu per
hour or less, and electric instantaneous water heaters with an input of
12 kilowatts or less; and
(c) Heat pump type units, with a maximum current rating of 24
amperes at a voltage no greater than 250 volts, which are products
designed to transfer thermal energy from one temperature level to a
higher temperature level for the purpose of heating water, including
all ancillary equipment such as fans, storage tanks, pumps, or controls
necessary for the device to perform its function. (42 U.S.C. 6291(27);
10 CFR 430.2)
In addition, at 10 CFR 430.2, DOE defines several specific
categories of consumer water heaters, as follows:

(1) ``Electric instantaneous water heater'' means a water heater
that uses electricity as the energy source, has a nameplate input
rating of 12 kW or less, and contains no more than one gallon of
water per 4,000 Btu per hour of input.
(2) ``Electric storage water heater'' means a water heater that
uses electricity as the energy source, has a nameplate input rating
of 12 kW or less, and contains more than one gallon of water per
4,000 Btu per hour of input.
(3) ``Gas-fired instantaneous water heater'' means a water
heater that uses gas as the main energy source, has a nameplate
input rating less than 200,000 Btu/h, and contains no more than one
gallon of water per 4,000 Btu per hour of input.
(4) ``Gas-fired storage water heater'' means a water heater that
uses gas as the main energy source, has a nameplate input rating of
75,000 Btu/h or less, and contains more than one gallon of water per
4,000 Btu per hour of input.
(5) ``Grid-enabled water heater'' means an electric resistance
water heater that--
(a) Has a rated storage tank volume of more than 75 gallons;
(b) Is manufactured on or after April 16, 2015;
(c) Is equipped at the point of manufacture with an activation
lock and;
(d) Bears a permanent label applied by the manufacturer that--
(i) Is made of material not adversely affected by water;
(ii) Is attached by means of non-water-soluble adhesive; and
(iii) Advises purchasers and end-users of the intended and
appropriate use of the product with the following notice printed in
16.5 point Arial Narrow Bold font: ``IMPORTANT INFORMATION: This
water heater is intended only for use as part of an electric thermal
storage or demand response program. It will not provide adequate hot
water unless enrolled in such a program and activated by your
utility company or another program operator. Confirm the
availability of a program in your local area before purchasing or
installing this product.''
(6) ``Oil-fired instantaneous water heater'' means a water
heater that uses oil as the main energy source, has a nameplate
input rating of 210,000 Btu/h or less, and contains no more than one
gallon of water per 4,000 Btu per hour of input.
(7) ``Oil-fired storage water heater'' means a water heater that
uses oil as the main energy source, has a nameplate input rating of
105,000 Btu/h or less, and contains more than one gallon of water
per 4,000 Btu per hour of input.

The definition for ``grid-enabled water heater'' includes the term
``activation lock,'' which is defined to mean a control mechanism
(either by a physical device directly on the water heater or a control
system integrated into the water heater) that is locked by default and
contains a physical, software, or digital communication that must be
activated with an activation key to enable the product to operate at
its designed specifications and capabilities and without which the
activation of the product will provide not greater than 50 percent of
the rated first-hour delivery of hot water certified by the
manufacturer. 10 CFR 430.2. As specified in this definition, the
control mechanism must be physically incorporated into the water heater
or, if a control system, integrated into the water heater to qualify as
an activation lock. DOE is aware of certain state programs that
encourage water heaters to be equipped with communication ports that
allow for demand-response communication between the water heater and
the utility.\9\ DOE notes that

[[Page 1561]]

presence of such a communication port, in and of itself, would not
qualify as an activation lock for the purpose of classifying a water
heater as a grid-enabled water heater.
---------------------------------------------------------------------------

\9\ On May 7, 2019, the State of Washington signed House Bill
1444, which amended the Revised Code of Washington (RCW) (i.e., the
statutory code in the State of Washington), Title 19, Chapter 19.260
(RCW 19.260). On January 6, 2020, the State of Washington amended
the Washington Administrative Code (WAC) (i.e., the regulatory code
in the State of Washington), Title 194, Chapter 194-24 (WAC 194-24)
(Washington January 2020 Amendment) to align with RCW 19.260.
Similarly, the State of Oregon published a final rule (Oregon August
2020 final rule) on August 8, 2020, which amended the Oregon
Administrative Rules (OAR), Chapter 330, Division 92 (OAR-330-092).
The Washington House Bill 1444 and the Oregon August 2020 final rule
established a definition for electric storage water heater (RCW
19.260.020(14); OAR-330-092-0010(10)), an effective date of January
1, 2021 in Washington and January 1, 2022 in Oregon (RCW
19.260.080(1); OAR-330-092-0015(17)), a requirement that electric
storage water heaters must have a modular demand response
communications port compliant with the March 2018 version of the
ANSI/CTA-2045-A communication interface standard, or a standard
determined to be equivalent (RCW 19.260.080(1)(a)-(b); OAR-330-092-
0020(17)), and, in Oregon, must bear a label or marking on the
products stating either ``DR-ready: CTA-2045-A'' or ``DR-ready: CTA-
2045-A and [equivalent DR system protocol]'' (OAR-330-092-0045(17)).
---------------------------------------------------------------------------

In the April 2020 RFI, DOE requested comment on the definitions
currently applicable to consumer water heaters. 85 FR 21104, 21108
(April 16, 2020). Sections III.A.1.a through III.A.1.e address specific
issues either requested by DOE or submitted by commenters.
a. Electric Heat Pump Storage Water Heater
In the April 2020 RFI, DOE requested feedback on the need for
creating a separate definition for ``electric heat pump storage water
heater,'' similar to the definition in the March 2019 ASHRAE Draft
118.2, or whether the current DOE definitions in 10 CFR 430.2 for
``electric storage water heater'' and ``water heater,'' which include
``heat pump type units,'' would adequately cover such products for the
purpose of performing the DOE test procedure. 85 FR 21104, 21110 (April
16, 2020). Rheem supported the creation of a separate definition for
electric heat pump storage water heaters, specifically to clarify power
rating limits and to include different design types. (Rheem, No. 14 at
p. 3) Rinnai supported the inclusion of a definition for electric heat
pump water heaters but not the creation of a separate product category.
(Rinnai, No. 13 at p. 4) EEI stated that DOE should adopt the March
2019 ASHRAE Draft 118.2 definition for electric heat pump storage water
heaters. (EEI, No. 8 at p. 3) On the other hand, BWC stated that the
definition for ``electric heat pump water heater'' is adequate at this
time. (BWC, No. 12 at p. 2) A.O. Smith stated that the introduction of
the electric heat pump water heater definition from the March 2019
ASHRAE Draft 118.2 is unnecessary and will cause confusion due to the
difference in scope, and that DOE's definitions for heat pump type
units with additional clarification regarding maximum amperage and
input power would be sufficient. (A.O. Smith, No. 20 at p. 2) AHRI
stated that DOE should carefully review the entire heat pump water
heater market, consider how each of the various designs should be
characterized, and consider changes to the definitions, as necessary.
(AHRI, No. 17 at p. 4) NEEA stated that no change to the definition is
needed yet as the ``heat pump type units'' definition is adequate as
written. (NEEA, No. 21 at p. 6) NEEA also requested that DOE clarify
the boundary between residential and commercial heat pump water heaters
for testing purposes and further stated that residential is implied to
include input rates lower than 6 kW,\10\ whereas commercial is implied
to include input rates greater than 12 kW, such that the 6-12 kW range
is ambiguous. (Id. at pp. 1-3)
---------------------------------------------------------------------------

\10\ Power equals amperage times voltage, so the definition of
consumer heat pump type unit corresponds to a maximum power rating
of 6,000 W, or 6 kW (24 A times 250 V equals 6,000 W).
---------------------------------------------------------------------------

DOE's consideration of the March 2019 ASHRAE Draft 118.2 ``electric
heat pump storage water heater'' definition, the comments received in
response to the April 2020 RFI, and a review of the market, lead DOE to
revisit its prior application of the water heater definition in the
context of heat pump type water heaters. DOE is re-evaluating these
terms with additional consideration of the distinction between heat
pump water heater consumer products and commercial products. More
specifically, DOE proposes to clarify the application of the ``heat
pump type'' provision in the EPCA definition of ``water heater.'' DOE
proposes that the ``heat pump type'' provision specifies the criteria
to distinguish consumer water heaters that incorporate heat pumps from
commercial water heaters that incorporate heat pumps.
As noted, EPCA defines water heater to include ``(A) storage type
units which heat and store water at a thermostatically controlled
temperature, including . . . electric storage water heaters with an
input of 12 kilowatts or less; (B) instantaneous type units which heat
water but contain no more than one gallon of water per 4,000 Btu per
hour of input, including . . . electric instantaneous water heaters
with an input of 12 kilowatts or less; and (C) heat pump type units,
with a maximum current rating of 24 amperes at a voltage no greater
than 250 volts, which are products designed to transfer thermal energy
from one temperature level to a higher temperature level for the
purpose of heating water, including all ancillary equipment such as
fans, storage tanks, pumps, or controls necessary for the device to
perform its function.'' (42 U.S.C. 6291(27))
``Storage type units'' and ``instantaneous type units'' are not
exclusive of ``heat pump type units.'' Based on the ``water heater''
definition, an electric heat pump type unit could be covered under the
water heater definition's description of storage type units (if it
heats and stores water at a thermostatically controlled temperature
with an input of 12 kilowatts or less) or instantaneous type unit (if
it heats water and contains no more than one gallon of water per 4,000
Btu per hour of input and has an input of 12 kilowatts or less). EPCA
is not explicit as to whether heat pump type units are considered a
subcategory of storage type units and instantaneous type units.
The November 2016 final rule treated heat pump type units as a
subcategory of the other two types of units listed in the definition of
water heater. Specifically, DOE stated in the November 2016 final rule
that a heat pump water heater with a total rated input of less than 12
kW would be a consumer water heater, as EPCA classifies electric water
heaters with less than 12 kW rated electrical input as consumer water
heaters. 81 FR 79261, 79301-79302 (Nov. 10, 2016). However, upon a
review of EPCA and the water heater market, DOE has tentatively
determined that the interpretation presented in the November 2016 final
rule is not the best reading of EPCA.
The structure of the statutory definition of ``water heater'' in
the Energy Conservation Program for Consumer Products in Part A of
EPCA, lists each type of water heater at equal subparagraph
designations. Therefore, when defining ``water heater'' for the purpose
of determining whether a water heater is a consumer water heater, the
energy use criteria specified for heat pump type units \11\ is to be
applied separately and distinctly from the criteria specified for the
broader categorizations of storage type units \12\ and instantaneous
type units.\13\
---------------------------------------------------------------------------

\11\ For heat pump type units EPCA specifies a maximum current
rating of 24 amperes at a voltage no greater than 250 volts. (42
U.S.C. 6291(27)(C))
\12\ For storage type units EPCA specifies gas storage water
heaters with an input of 75,000 Btu per hour or less, oil storage
water heaters with an input of 105,000 Btu per hour or less, and
electric storage water heaters with an input of 12 kilowatts or
less. (42 U.S.C. 6291(27)(A))
\13\ For instantaneous type units EPCA specifies gas
instantaneous water heaters with an input of 200,000 Btu per hour or
less, oil instantaneous water heaters with an input of 210,000 Btu
per hour or less, and electric instantaneous water heaters with an
input of 12 kilowatts or less. (42 U.S.C. 6291(27)(B))
---------------------------------------------------------------------------

This separate consideration of heat pump type units when defining
the scope of the consumer water heater definition is further supported
by

[[Page 1562]]

considering the output capacities associated with the input limits
specified for each type of unit. The electrical requirements for heat
pump type water heaters (i.e., less than or equal to 24 amperes (A) at
250 volts (V) or less) align with common electrical requirements for a
residential electrical circuit.\14\ EPCA's energy use criteria for heat
pump type units corresponds to an input rate of 6 kW.\15\ Whereas,
DOE's interpretation in the November 2016 final rule additionally
applies the 12 kW input rate limit to heat pump type units. A heat pump
type unit with an input rate of 12 kW would have a heating capacity
(i.e., output capacity) of approximately 42 kW, which is 3.6 times the
output heating capacity provided by the largest possible consumer
electric storage type water heater (i.e., 11.8 kW).\16\ While a heat
pump type unit with a 12 kW input capacity could theoretically be
designed and installed in a residential application, a water heating
capacity (i.e., output capacity) of 42 kW would far exceed the water
heating demand of any residential installation.
---------------------------------------------------------------------------

\14\ In a safely designed home electrical circuit, a circuit
breaker should only service outlets and/or devices that add up to 80
percent of the maximum current rating for the circuit breaker (i.e.,
a 30 A circuit breaker should only service up to 24 A across all
outlets and/or devices connected to that circuit breaker). Further,
large appliances, such as water heaters, if installed on a dedicated
circuit, should not exceed 80 percent of the circuit rating. See
section 550.12(D) of the 2019 California Electrical Code:
<a href="http://www.nfpa.org/codes-and-standards/all-codes-and-standards/codes-and-standards/free-access?mode=view">www.nfpa.org/codes-and-standards/all-codes-and-standards/codes-and-standards/free-access?mode=view</a>.
\15\ Power (in watts) is calculated as current (i.e., amperage)
multiplied by voltage. The EPCA criteria of 24 A and 250 V
correspond to a power of 6,000 W (i.e., 24 x 250 = 6,000), or 6 kW.
\16\ A 12-kW electric resistance water heater with an assumed
recovery efficiency of 98 percent would have an output heating
capacity of 11.8 kW (i.e., 12 kW x 0.98 = 11.8 kW). Whereas, an
electric heat pump type water heater with a 12 kW input capacity,
with an assumed recovery efficiency of 350 percent, would have an
output heating capacity of 42 kW (i.e., 12 kW x 3.5 = 42 kW), which
is 3.6 times greater than the 11.8 kW output heating capacity of an
electric resistance water heater with equivalent input capacity.
---------------------------------------------------------------------------

This tentative interpretation is supported by the current market.
DOE reviewed manufacturers' product literature and found no electric
heat pump water heaters marketed towards residential use that were
designed to operate at greater than 24 A at 250 V.
This proposed interpretation of the ``heat pump type'' provision
would define the scope of ``water heater'' for the purpose of Part A of
EPCA. The interpretation would not be applicable in the context of
determining product classes for water heaters. Any such consideration
of product classes would be governed by 42 U.S.C. 6295(q). As stated
previously, ``storage type units'' and ``instantaneous type units'' are
not exclusive of ``heat pump type units.'' The criteria established in
the statutory definition of water heater for each of these types of
units in the definition of ``water heater'' excludes units with
capacities that would be more appropriately addressed as commercial
water heaters.
When considering the unit types included in the water heater
definition (i.e., ``storage type,'' ``instantaneous type,'' and ``heat
pump type'') as separate and distinct elements, the statutory
definition of consumer water heater includes only those heat pump type
units that have a maximum current rating of 24 A at a voltage no
greater than 250 V. Heat pump type water heaters with an input capacity
greater than the 24 A at 250 V do not meet the EPCA definition of a
covered water heater. Instead, such units would be commercial water
heaters, i.e., if a heat pump type water heater has either an amperage
greater than 24 A or a voltage greater than 250 V, under the definition
it would be a commercial water heater.
EPCA defines covered equipment as certain types of industrial
equipment, including storage water heaters and instantaneous water
heaters. (42 U.S.C. 6311(1)(K)) EPCA defines ``industrial equipment,''
in relevant part, as ``any article of equipment [. . .] which is not a
``covered product'' as defined in 42 U.S.C. 6291(a)(2). (42 U.S.C.
6311(2)(A)) In the context of covered equipment, EPCA defines ``storage
water heater'' as a water heater that heats and stores water within the
appliance at a thermostatically controlled temperature for delivery on
demand. Such term does not include units with an input rating of 4,000
Btu per hour or more per gallon of stored water. (42 U.S.C.
6311(12)(A)) The term ``instantaneous water heater'' is defined in the
context of covered equipment as a water heater that has an input rating
of at least 4,000 Btu per hour per gallon of stored water. (42 U.S.C.
6311(12)(B)) Under these EPCA definitions, a heat pump type water
heater that was not defined as a consumer water heater would be either
a commercial storage water heater or a commercial instantaneous water
heater, depending on the input rating.
DOE has tentatively determined that heat pump water heaters, which
operate with a maximum current rating greater than 24 A or at a voltage
greater than 250 V, are more appropriately covered as commercial water
heaters than consumer water heaters.
As discussed in the November 2016 final rule, electric heat pump
water heaters with greater than 24 A at 250 V and a total input rate
less than or equal to 12kW would be covered by the energy conservation
standards for consumer electric storage water heaters. See 81 FR 79261,
79301-79302. (Nov. 10, 2016). These standards for consumer electric
storage water heaters effectively require electric resistance
technology at less than or equal to 55 gallons of rated storage volume
or baseline \17\ heat pump technology at greater than 55 gallons of
rated storage volume. However, section 1.12.3 of the DOE test procedure
at the time \18\ only included heat pump water heaters which have ``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.'' Therefore, electric heat pump water heaters with greater than
24 A at 250 V were not considered in the analysis of the April 2010
final rule, and, as such, the electric storage water heater standards
are not applicable to these heat pump water heaters. Under the proposed
interpretation in this NOPR, electric heat pump water heaters with
greater than 24 A at 250 V and a total input rate less than or equal to
12kW would be subject to the commercial water heater standards, which
specify a maximum standby loss. 10 CFR 431.110(a). DOE notes that it
has established a test procedure for commercial water heaters (10 CFR
431.106), and any representation made by a manufacturer as to the
energy efficiency or energy use of a commercial water heater must be
based on testing in accordance with the DOE test procedure, and such
representation must fairly disclose the results of such testing. (42
U.S.C. 6314(d)(1))
---------------------------------------------------------------------------

\17\ The electric storage water heater energy conservation
standards established by the April 2010 final rule set a minimum
efficiency level that was attainable by all heat pump water heaters
available at the time. Therefore, the standard did not eliminate any
heat pump water heaters from the market.
\18\ At the time of the April 2010 final, rule, the DOE test
procedure for consumer water heaters was last updated by a final
rule published on July 20, 1998. 63 FR 38737.
---------------------------------------------------------------------------

In determining the input rate of a water heater with a heat pump
component for the purpose of classifying such a water heater as either
a consumer water heater or a commercial water heater, DOE would
consider the total input rate, including all heat pump components and
the resistive elements. As specified in the definition of ``water
heater'' and ``commercial heat pump water heater,'' determination of
the rated electric power input includes all ancillary

[[Page 1563]]

equipment. 10 CFR 430.2 and 10 CFR 431.102. Similarly, DOE would
consider all heat pump components and resistive elements in determining
voltage and amperage.
DOE reviewed the electric heat pump water heater market and found
that several new configurations of heat pump water heaters have either
become available or will soon become available on the market. Based its
review of the market, DOE has identified these new configurations as
electric storage water heaters that are heat pump type units.
In the present market, a consumer heat pump water heater typically
consists of an air-source heat pump and a storage tank that are
integrated together into one assembly. This ``typical'' consumer heat
pump water heater uses electricity, operates around 240 volts, and has
two 4,500-watt backup resistance elements within the storage tank that
operate non-simultaneously. The new configurations that DOE identified
include split-system heat pump water heaters (which consist of a
separate heat pump and storage tank that are sold together), heat pump
only models (which are sold without a storage tank but require being
paired with one), ``retrofit-ready'' or ``plug-in'' heat pump water
heaters (which are integrated heat pump and storage tank water heaters
that can operate on a shared 120V/15A circuit and plugged into a
standard 120 V receptacle (i.e., wall outlet)), and ground- or water-
source heat pump water heaters.
Split-system heat pump water heaters are currently available and
used in residential applications; however, they are relatively uncommon
when compared to typical integrated heat pump water heaters. Although
split-system heat pump water heaters are more prevalent outside of the
United States, they are produced by manufacturers that sell water
heaters within the United States. As such, split-system water heaters
may become more prevalent in the U.S. market in the future, and the DOE
test procedure should adequately test these products. The current DOE
test procedure covers split-system heat pump water heaters and the
relevant proposed amendments are discussed in section III.C.8.b of this
document. DOE has tentatively determined that split-system heat pump
water heaters are covered by the current definitions of ``electric
storage water heater'' and ``heat pump type units.''
DOE has identified heat pump water heaters models that are sold
with only the heat pump (heat pump only water heaters) and must be
paired with an external storage tank in the field, with the specific
tank characteristics depending on the hot water requirements of the
installation (i.e., the heat pump can be used with storage tanks of
various storage volumes). Currently, these units are marketed only for
commercial use. However, some models of these units have rated voltage
and amperage values below the limits specified in the ``heat pump type
unit'' consumer water heater definition. Further, DOE has identified
models that will soon enter the market that are marketed for
residential and light-commercial use. To the extent that a heat pump
only water heater is covered by the definition of ``heat pump type
unit'' consumer water heater, it would be subject to the DOE test
procedure for consumer water heaters. DOE proposes to add a definition
to cover heat pump only water heaters to 10 CFR 430.2. This definition
is presented in section III.A.1.c of this document where products with
a similar application are discussed. Test procedure amendments proposed
in this document specific to heat pump only water heaters are discussed
in section III.C.8.c of this NOPR.
DOE reviewed the plug-in (or ``retro-fit ready'') heat pump water
heater market described previously (integrated heat pump and storage
tank water heaters that can operate on a 120V/15A circuit and plugged
into a standard 120 V receptacle (i.e., wall outlet)) and has initially
found that these products are still under development and are not
commercially available at this time. On December 23, 2019, NEEA
published version 7.0 of its Advanced Water Heating Specification,\19\
which includes an appendix that describes plug-in heat pump water
heaters. As reported, these products are being designed as an
integrated heat pump and storage tank for space-constrained
installations (e.g., small closets) and to operate on a shared 120V/15A
circuit. Indications are that plug-in heat pump water heaters will be
marketed for residential use, have input rates at or below the 12 kW
threshold to be considered a consumer electric storage water heater,
and have voltage and amperage levels below the 250 V and 24 A limits to
be considered a ``heat pump type unit.'' Based on the initial
information available, plug-in heat pump water heaters would be covered
by either the current definition of ``electric storage water heater''
or ``heat pump type units.'' As plug-in heat pump water heaters are not
currently available on the market, DOE is not proposing any changes to
the test procedure specific to these products in this NOPR. DOE may
reevaluate this tentative determination at such time as when these
models enter the market.
---------------------------------------------------------------------------

\19\ Version 7.0 of NEEA's Advanced Water Heater Specification
can be found at: <a href="http://www.neea.org/img/documents/Advanced-Water-Heating-Specification.pdf">www.neea.org/img/documents/Advanced-Water-Heating-Specification.pdf</a>.
---------------------------------------------------------------------------

DOE has also identified heat pump water heaters that use
alternative heat sources (e.g., water- or ground-source) that, although
more commonly installed in commercial applications, do have residential
applications and are at or below the 12kW limit to be considered a
consumer ``water heater.'' Alternative source heat pump water heaters
were not prevalent in the market at the time DOE established the
current consumer water heater test procedure and therefore were not
considered in the development of the current DOE test procedure. 79 FR
40542, 40566-40567 (July 11, 2014).
Significant changes and clarifications to the test setup and test
conditions would be required to appropriately represent the various
alternative source heat pump water heater components and installation
requirements. The current test procedure for consumer water heaters
incorporates draw patterns to represent an average period of use for
the products subject to the test procedure. Section 5.4.1 of appendix
E. Alternative source heat pump water heaters were not considered in
the development of the current draw pattern requirements. Based on a
current review of the market, these water heaters continue to have a
small market share and indications are that they are predominantly used
in commercial applications. DOE currently does not have data as to the
use of such water heaters as installed. Absent such data, DOE is unable
to develop and propose test procedure provisions that would be
representative of such water heaters during an average period of use.
To the extent there is no test procedure for such covered water
heaters, they would not be subject to energy conservation standards.
Because of the limited market share and unavailability of usage data,
DOE has tentatively determined not to propose test procedures for these
products.
Based on the forgoing discussion, DOE has tentatively determined
that the current definitions of ``heat pump type'' and ``electric
storage water heaters'' adequately cover the electric heat pump water
heaters on the market that are representative of residential use,
including ``plug in'' and alternative source heat pump water heaters,
and that a separate definition for ``electric heat pump water heaters''
is not needed at this time. However, as discussed previously in this
NOPR, DOE is

[[Page 1564]]

proposing to add a new definition to cover heat pump only water
heaters.
b. Gas-Fired Heat Pump Storage Water Heater
In the April 2020 RFI, DOE requested feedback on whether a separate
definition for ``gas-fired heat pump storage water heater,'' similar to
the definition in the March 2019 ASHRAE Draft 118.2, was needed or
whether the current DOE definitions in 10 CFR 430.2 for ``gas-fired
storage water heater'' and ``water heater,'' which include ``heat pump
type units,'' would adequately cover such products for the purpose of
performing the DOE test procedure. 85 FR 21104, 21110 (April 16, 2020).
AHRI, A.O. Smith, BWC, EEI, Rheem, Rinnai, and SMTI recommended that
DOE add a separate definition for ``gas-fired heat pump storage water
heater.'' (AHRI, No. 17 at p. 4; A.O. Smith, No. 20 at p. 2; BWC, No.
12 at p. 2; EEI, No. 8 at p. 3; Rheem, No. 14 at p. 3; Rinnai, No. 13
at p. 4; SMTI, No. 19 at p. 2) A.O. Smith further stated that the gas-
fired storage water heater input capacity limit (less than or equal to
75,000 Btu/h) is not appropriate for defining a gas-fired heat pump
storage water heater that is representative of residential
applications. (A.O. Smith, No. 20 at p. 2) AHRI stated that a separate
definition for ``gas-fired heat pump water heater'' is appropriate and
that DOE had already established a definition for it as part of the
July 2014 final rule. (AHRI, No. 17 at p. 4) However, CEC stated there
is no need to add a definition for ``gas-fired heat pump storage water
heater'' because the definition currently in 10 CFR 430.2 for ``gas-
fired storage water heater'' and ``water heater'' includes ``heat pump
type units,'' which adequately covers gas-fired heat pump storage water
heaters. (CEC, No. 11 at p. 2) CEC argued that introducing the new
definition as suggested under the March 2019 ASHRAE Draft 118.2 would
indirectly limit the scope of heat pump water heaters standards by
limiting the size of the gas-fired heat pump water heaters to be
tested. (Id.) NEAA agreed that the current definitions for ``gas-fired
storage water heater'' and ``heat pump units'' are adequate to cover
gas-fired heat pump storage water heaters for purposes of testing, but
the commenter noted there is value in creating a definition for market
clarity. (NEEA, No. 21 at p. 6)
In the July 2014 final rule, DOE defined a ``gas-fired heat pump
water heater'' as ``a water heater that uses gas as the main energy
source, has a nameplate input rating of 75,000 Btu/h (79 MJ/h) or less,
has a maximum current rating of 24 amperes (including all auxiliary
equipment such as fans, pumps, controls, and, if on the same circuit,
any resistive elements) at an input voltage of no greater than 250
volts, has a rated storage volume not more than 120 gallons (450
liters), and is designed to transfer thermal energy from one
temperature level to a higher temperature level to deliver water at a
thermostatically controlled temperature less than or equal to 180
[deg]F (82 [deg]C).'' 79 FR 40542, 40567 (July 11, 2014). DOE also
stated that gas-fired heat pump water heaters are covered by the test
procedure established in the July 2014 final rule. Id. at 79 FR 40549.
The November 2016 final rule replaced this definition with the current
definition of ``gas-fired storage water heater.'' 81 FR 79261, 79320-
79321 (Nov. 10, 2016). The current definition of ``water heater,''
which includes ``heat pump type units'' was added in a final rule
published on February 7, 1989. 54 FR 6062, 6075. DOE reasoned in the
November 2016 final rule that, because the definition of ``gas-fired
heat pump water heater'' is not used in DOE's test procedures or energy
conservation standards for consumer waters, removing this definition
will have no effect on the implementation of DOE's regulations. 81 FR
79261, 79287.
Currently, a water heater that uses gas as the main energy source,
has a nameplate input rating of 75,000 Btu/h or less, and contains more
than one gallon of water per 4,000 Btu per hour of input is a gas-fired
storage water heater. 10 CFR 430.2. If the gas-fired storage water
heater also has a heat pump with a maximum current rating of 24 amperes
at a voltage no greater than 250 volts, is designed to transfer thermal
energy from one temperature level to a higher temperature level for the
purpose of heating water, including all ancillary equipment such as
fans, storage tanks, pumps, or controls necessary for the device to
perform its function, it would be a heat pump type unit. 10 CFR 430.2.
This definition of heat pump type unit is not exclusive of gas-fired
units.
The input rate of models currently in development for residential
application are less than 20,000 Btu/h, which the March 2019 ASHRAE
Draft 118.2 defines as the limit for gas-fired heat pump water heaters,
and which is well below the 75,000 Btu/h limit in DOE's regulations.
Gas-fired heat pump water heaters currently under design will likely
have voltage and amperage requirements below the DOE ``heat pump type
unit'' requirements, as electricity is not the main fuel source.
Recognizing that the market for heat pump type units that are gas-fired
is still developing, limiting coverage to less than 20,000 Btu/h
(consistent with March 2019 ASHRAE Draft 118.2) would not accommodate
the potential for future products designed for residential applications
that may have input rates above 20,000 Btu/h. Therefore, DOE has
tentatively determined that the definitions of ``heat pump type'' and
``gas-fired storage water heaters'' adequately cover the water heaters
that are within the ASHRAE definition of ``gas-fired heat pump water
heaters,'' and a separate DOE regulatory definition is not needed at
this time. Further, as DOE stated in the July 2014 final rule, gas-
fired heat pump water heaters are covered by the DOE test procedure
established in that rule. 79 FR 40542, 40549 (July 11, 2014).
c. Gas-Fired Instantaneous Water Heater
As discussed previously in this document, a gas-fired instantaneous
water heater is a water heater that uses gas as the main energy source,
has a nameplate input rating less than 200,000 Btu/h, and contains no
more than one gallon of water per 4,000 Btu per hour of input. 10 CFR
430.2. In the April 2020 RFI, DOE requested feedback on the typical
application of a specific configuration of gas-fired instantaneous
water heaters, commonly referred to as ``circulating gas-fired
instantaneous water heaters.'' 85 FR 21104, 21113 (April 16, 2020). As
explained in the April 2020 RFI, DOE has found that several
manufacturers produce consumer gas-fired instantaneous water heaters
that are designed to be used with a volume of stored water (usually in
a tank, but sometimes in a recirculating hot water system of sufficient
volume, such as a hydronic space heating or designated hot water
system) in which the water heater does not provide hot water directly
to fixtures, such as a faucet or shower head, but rather replenishes
heat lost from the tank or system through hot water draws or standby
losses by circulating water to and from the tank or other system. Id.
These circulating gas-fired instantaneous water heaters are typically
activated by an aquastat \20\ installed in a storage tank that is sold
separately or by an inlet water temperature sensor. Id. DOE further
stated that while the products identified by DOE are within the
statutory and regulatory definition of a consumer water heater as a
covered product, the design and application of circulating gas-fired
instantaneous water heaters makes testing to the consumer water

[[Page 1565]]

heater test procedure difficult, if not impossible, as these products
are not capable of delivering water at the temperatures and flow rates
specified in the UEF test method. Id.
---------------------------------------------------------------------------

\20\ An ``aquastat'' is a temperature measuring device typically
used to control the water temperature in a separate hot water
storage tank.
---------------------------------------------------------------------------

In response to the April 2020 RFI, AHRI, APGA, Rheem, and Rinnai
recommended generally that DOE amend the regulatory definitions of gas-
fired instantaneous water heaters to exclude models designed
exclusively for commercial use with input rates below the consumer
water heater input rate limit (i.e., <=200,000 Btu/h) and provided
circulating gas-fired instantaneous water heaters as an example. (AHRI,
No. 17 at p. 2; APGA, No. 16 at pp. 1-2; Rheem, No. 14 at p. 2; Rinnai,
No. 13 at p. 2) A.O. Smith addressed circulating gas-fired water
heaters specifically, stating that these models are produced at input
rates both above and below the consumer water heater input rate cut-off
for gas-fired instantaneous water heaters, and that all circulating
water heaters, regardless of input rate, serve commercial applications;
as such, they should be excluded from the consumer water heater
regulations. (A.O. Smith, No. 20 at pp. 1-2) AHRI, Rheem, and Rinnai
stated that these types of water heaters are sold into commercial
building applications and should not be tested using a residential draw
profile, which would not be applicable. (AHRI, No. 17 at p. 11; Rheem,
No. 14 at p. 8; Rinnai, No. 13 at p. 10)
Currently, an enforcement policy \21\ is in place addressing
circulating water heaters. As provided in the enforcement policy, DOE
will not seek civil penalties for the failure to properly certify
covered products or the distribution in commerce by a manufacturer or
private labeler of covered products that are not in compliance with an
applicable energy conservation standard, if the violation occurs on or
before December 31, 2021, with respect to an individual model of water
heater that:
---------------------------------------------------------------------------

\21\ Enforcement policy for circulating water heaters is
available at: <a href="http://www.energy.gov/sites/prod/files/2019/09/f66/Enforcement%20Policy-CirculatingWH.92019.pdf">www.energy.gov/sites/prod/files/2019/09/f66/Enforcement%20Policy-CirculatingWH.92019.pdf</a>.
---------------------------------------------------------------------------

<bullet> Meets the statutory definition of an instantaneous type of
consumer water heater per 42 U.S.C. 6291(27);
<bullet> Does not have an operational scheme in which the burner or
heating element initiates and terminates heating based on sensing flow;
<bullet> Has a water temperature sensor located at the inlet of the
water heater or in a separate storage tank that is the primary
operating temperature means of initiating and terminating heating;
<bullet> Must be used in combination with a recirculating pump and
either a separate storage tank or water circulation loop in order to
achieve the water flow and temperature conditions recommended in the
manufacturer's installation and operation instructions;
<bullet> Is designed to provide outlet hot water at a
thermostatically controlled temperature greater than 180 [deg]F; and
<bullet> Meets the corresponding energy conservation standards in
10 CFR 431.110.
As provided in the enforcement policy, a water heater must first
meet the statutory definition of an instantaneous type of consumer
water heater per 42 U.S.C. 6291(27) in order to be a circulating water
heater. Inherent to being a water heater per 42 U.S.C. 6291(27), a
product must be a ``consumer product.'' DOE's authority under the
Energy Conservation Program for Consumer Products Other Than
Automobiles established by EPCA (42 U.S.C. 6291-6309) applies to
``consumer products.'' (See 42 U.S.C. 6292)
In relevant part, 42 U.S.C. 6291(1) states that a ``consumer
product'' means any article of a type which, to any significant extent,
is distributed in commerce for personal use or consumption by
individuals. Through an examination of product literature, DOE has
found that circulating water heaters are predominately marketed for
commercial applications. However, the input rates of many of the
available models are below the maximum input rate of a consumer water
heater and can therefore be suitable for residential applications. As
such, DOE has tentatively determined that circulating water heaters are
covered ``consumer products.'' Further, circulating water heaters
operate similarly to the heat pump only water heaters discussed in
section III.A.1.a, which DOE tentatively determined are marketed
towards consumers and have residential applications (e.g., they extract
water from a storage tank, heat the water, and return the heated water
to the storage tank). The circulating water heaters currently on the
market circulate water at high flow rates (e.g., greater than 10 gpm)
and are, for the most part, designed to deliver water at a temperature
greater than 180 [deg]F. These characteristics suggest that the
circulating water heaters on the market would not be appropriate for
residential applications. However, when developing the test procedure
currently in appendix E, DOE is required to develop a test procedure
that applied, to the maximum extent practicable, to all water heating
technologies in use and to future water heating technologies. (42
U.S.C. 6295(e)(5)(H)) As a circulating water heater could be designed
to operate in a similar manner to other consumer water heaters (i.e.,
heat pump only water heaters) and at conditions appropriate for
residential applications, DOE is required to amend appendix E to
address these products.
DOE proposes to add the definition described below for circulating
water heaters to 10 CFR 430.2. The proposed definition also covers heat
pump only water heaters which are discussed in section III.A.1.a in
this NOPR. Test procedure amendments for circulating water heaters are
discussed in section III.C.9 of this document.
DOE proposes to define ``circulating water heater'' at 10 CFR 430.2
as ``an instantaneous or heat pump type water heater that does not have
an operational scheme in which the burner, heating element, or
compressor initiates and terminates heating based on sensing flow; has
a water temperature sensor located at the inlet of the water heater or
in a separate storage tank that is the primary means of initiating and
terminating heating; and must be used in combination with a
recirculating pump and either a separate storage tank or water
circulation loop in order to achieve the water flow and temperature
conditions recommended in the manufacturer's installation and operation
instructions.''
With regard to the other gas-fired instantaneous water heaters
referenced by commenters, DOE has also examined the market for gas-
fired instantaneous water heaters with an emphasis on product lines
with input rates both above and below the consumer and commercial input
rate threshold of 200,000 Btu/h. The models with an input rate at or
below the 200,000 Btu/h threshold could be used in consumer
applications, are nearly indistinguishable from water heaters marketed
and used in consumer applications, and are completely self-contained;
that is, no other components would be required for these products to
operate within a residence. As such, DOE has tentatively determined
that these models continue to be considered ``consumer products'' and
are subject to the test procedures and energy conservation standards
for consumer gas-fired instantaneous water heaters.
DOE has also examined gas-fired water heaters with input rates of
200,000 Btu/h or less, containing less than one gallon of water per
4,000 Btu/h of input, and with rated storage volumes greater than 2
gallons. In the July 2014 final rule, storage volume requirements were
removed from the definition of a ``gas-fired instantaneous water
heater.'' 79 FR 40542, 40567 (July 11, 2014). In the December 2016
final

[[Page 1566]]

rule, DOE stated that definitions for consumer water heaters added to
EPCA under the National Appliance Energy Conservation Act of 1987
(NAECA; Pub. L. 100-12 (March 17, 1987)), which amended EPCA, do not
place any limitation on the storage volume of consumer water heaters.
(42 U.S.C. 6291(27); 81 FR 96204, 96210 (Dec. 29, 2016)) DOE further
stated that the energy conservation standards established by EPCA for
consumer water heaters apply to all consumer water heaters regardless
of storage volume. 81 FR 96204, 96210. DOE also acknowledged that its
delay in issuing test procedures for such products, as well as
statements it has made in the past, may have caused confusion about
whether these products are covered by energy conservation standards for
consumer water heaters, and that achieving compliance with the
statutory standards immediately would be quite burdensome for industry.
Id. at 81 FR 96211. As such, DOE stated that it will not enforce the
statutory standards applicable to these products until some point after
DOE finalizes a conversion factor and the converted standards
applicable to those products. Id. DOE has tentatively determined that
the interpretation presented in the December 2016 final rule for gas-
fired instantaneous water heaters with storage volume greater than 2
gallons is still valid.
d. Tabletop Water Heaters
On January 17, 2001, DOE published a final rule (January 2001 final
rule) that established definitions and created a separate product class
for tabletop water heaters. 66 FR 4474. A ``tabletop water heater,''
was defined in the January 2001 final rule as a water heater in a
rectangular box enclosure designed to slide into a kitchen countertop
space with typical dimensions of 36 inches high, 25 inches deep, and 24
inches wide. Id. at 66 FR 4497. The definition for ``tabletop water
heater'' was removed from appendix E as part of the July 2014 final
rule and was inadvertently not added to 10 CFR 430.2. 79 FR 40542,
40567-40568 (July 11, 2014). However, energy conservation standards for
tabletop water heaters are still specified at 10 CFR 430.32(d).
In the April 2020 RFI, DOE requested feedback on whether the
previous definition for ``tabletop water heater'' is still appropriate,
and whether such products should continue to be considered separately
from other classes of consumer water heaters. 85 FR 21104, 21108 (April
16, 2020). AHRI, A.O. Smith, BWC, Rheem, and Rinnai commented that the
definition for ``tabletop water heater'' is still appropriate and
should remain as a separate product class. (AHRI, No. 17 at p. 3; A.O.
Smith, No. 20 at p. 2; BWC, No. 12 at p. 2; Rheem, No. 14 at p. 2;
Rinnai, No. 13 at p. 2) EEI suggested that the definition include a
rated capacity of at least 20 gallons and exclude the phrases
``rectangular box'' and ``designed to slide into a kitchen countertop
space'' to make the definition broader. (EEI, No. 8 at p. 3) Keltech
stated that point-of-use (POU) units may benefit from being classified
as a ``tabletop water heater'' and that a category should be created
for POU water heaters that can be installed under a countertop.
(Keltech, No. 7 at p. 1)
In the January 2001 final rule, DOE separated tabletop water
heaters from the electric storage water heater product class ``due to
strict size limitations for these products.'' 66 FR 4474, 4478 (Jan.
17, 2001). Tabletop water heaters are a unique type of water heater
that are designed to fit into a countertop and provide a working
surface in the installed location; as such, they are inherently size-
constrained. DOE has tentatively determined that excluding the phrases
``rectangular box'' and ``designed to slide into a kitchen countertop
space'' would make the tabletop water heater definition broader but
would also remove the distinction of the key features that distinguish
tabletop water heaters from electric storage water heaters (i.e., the
tabletop water heater product class addresses the very specific size
limitations and location installations associated with these products).
Further, the addition of a minimum rated storage volume of 20 gallons
would define a scope of coverage that might not include the full volume
range of water heaters in a rectangular box enclosure designed to slide
into a kitchen countertop space. Therefore, DOE has tentatively
determined not to add a minimum rated storage volume.
A POU water heater is, in general terms, a water heater that is
located where the hot water is needed (e.g., under a sink or counter).
Water heaters that are installed under sinks or counters are typically
small electric storage water heaters (30 gallons or less) or electric
instantaneous water heaters. For small electric storage water heaters,
these products are currently covered by the definition for electric
storage water heater, which does not have storage volume requirements.
See 10 CFR 430.2. The test procedure for electric storage water heaters
varies slightly depending on the delivery capacity of the water heater,
which is a result of the first-hour rating test. See section 5.4.1 of
appendix E. DOE has tentatively determined that POU or small electric
storage water heaters are adequately covered by the current DOE test
procedure when tested to the very small or low draw patterns. The same
can be said for electric instantaneous water heaters, for which the
test procedure also varies slightly depending on the delivery capacity
of the water heater, which is a result of the Max GPM test. See section
5.4.1 of appendix E.
For the reasons discussed previously, DOE proposes to add the
``tabletop water heater'' definition that was removed from appendix E
in the July 2014 final rule to 10 CFR 430.2.
e. Residential-Duty Commercial Water Heaters
In the April 2020 RFI, DOE requested comment on the definition for
``residential-duty commercial water heater,'' which defines a category
of commercial water heaters that are subject to the consumer water
heater test procedure. 85 FR 21104, 21108 (April 16, 2020). AHRI, A.O.
Smith, Rheem, and Rinnai supported the current definition of
``residential-duty commercial water heater'' and had no recommended
changes. (AHRI, No. 17 at p. 3; A.O. Smith, No. 20 at p. 2; Rinnai, No.
13 at p. 3; Rheem, No. 14 at p. 2) Keltech recommended adding the
intended market for the water heater as another criteria for
determining whether a water heater is a residential-duty commercial
water heater and stated that if a water heater is not intended for sale
in a consumer setting, it should not be held to consumer requirements.
(Keltech, No. 7 at p. 1) DOE acknowledges that some water heaters,
which are intended for commercial use, are covered by the residential-
duty commercial water heater definition and tested and rated to the
consumer water heater test procedure and residential-duty commercial
water heater energy conservation standards. These water heaters have
characteristics that are similar to water heaters with residential
applications and, as such, under 42 U.S.C. 6295(e)(5)(F), cannot be
excluded from being tested and rated using the consumer water heaters
test procedure and residential-duty commercial water heater energy
conservation standards. Further, DOE has tentatively determined that
whether a product is marketed as commercial or residential may not
always be indicative of the intended installation location. For
example, water heaters intended for residential use are sometimes
marketed as ``commercial-grade'' as a means to convey

[[Page 1567]]

reliability.\22\ Therefore, DOE has tentatively determined not to amend
the definition for ``residential-duty commercial water heater.''
---------------------------------------------------------------------------

\22\ A water heater designed to be installed in commercial
applications will typically be used more often and be subjected to
environments that are harsher than would be experienced by a water
heater designed to be installed in residential application.
Therefore, a ``commercial-grade'' water heater could be considered
more reliable, as it can operate longer in such an environment
without malfunctioning.
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B. Updates to Industry Standards

The current DOE test procedure in appendix E references the
following industry standards:
<bullet> ASHRAE 41.1-1986 (Reaffirmed 2006), Standard Method for
Temperature Measurement (ASHRAE 41.1-1986 (RA 2006)); and
<bullet> ASTM D2156-09, (ASTM D2156-09), Standard Test Method for
Smoke Density in Flue Gases from Burning Distillate Fuels.
ASHRAE 41.1-1986 (RA 2006) was superseded by ASHRAE 41.1-2013 on
January 30, 2013 (ASHRAE 41.1-2013). ASHRAE 41.1-2013 was superseded by
ASHRAE 41.1-2020 on June 30, 2020. Updates to ASHRAE 41.1 are discussed
in section III.B.1.
ASTM D2156-09 was reapproved without modification in 2018 (ASTM
D2156-09 (RA 2018)). Therefore, DOE proposes to update the reference of
ASTM D2156-09 to the most recent industry standard (i.e., ASTM D2156-09
(RA 2018)). ASTM D2156-09 and ASTM D2156-09 (RA 2018) directly
reference ASTM E97-1987 (W1991), which is necessary to perform the
procedures within ASTM D216-09 and ASTM D2156-09 (RA 2018). Therefore,
DOE also proposes to incorporate by reference ASTM E97-1987 (W1991).
ASHRAE maintains a published water heater test procedure titled,
``ANSI/ASHRAE Standard 118.2-2006 (RA 2015), Method of Testing for
Rating Residential Water Heaters'' (ANSI/ASHRAE 118.2-2006 (RA 2015)).
The ANSI/ASHRAE 118.2-2006 (RA 2015) test procedure is similar to the
DOE test procedure that was in effect prior to the July 2014 final
rule, although neither the former nor the current DOE consumer water
heater test procedure reference ANSI/ASHRAE Standard 118.2-2006 (RA
2015). In March 2019, ASHRAE published the March 2019 ASHRAE Draft
118.2, the second public review draft of Board of Standards Review
(BSR) ANSI/ASHRAE Standard 118.2-2006R, ``Method of Testing for Rating
Residential Water Heaters and Residential-Duty Commercial Water
Heaters,'' which DOE referenced in the April 2020 RFI. 85 FR 21104,
21109-21111 (April 16, 2020). In April 2021, ASHRAE published
substantive changes to a previous public review draft \23\ of BSR ANSI/
ASHRAE Standard 118.2-2006R, ``Method of Testing for Rating Residential
Water Heaters and Residential-Duty Commercial Water Heaters.'' (April
2021 ASHRAE Draft 118.2) The March 2019 ASHRAE Draft 118.2 and April
2021 ASHRAE Draft 118.2 are examined together in section III.B.2. Both
the March 2019 ASHRAE Draft 118.2 and April 2021 ASHRAE Draft 118.2 are
similar to the current DOE test procedure but include some differences
throughout, some of which would result in test procedure results
different from the current DOE test procedure.
---------------------------------------------------------------------------

\23\ The April 2021 ASHRAE Draft 118.2 shows only the proposed
substantive changes to the March 2019 ASHRAE Draft 118.2. All
sections not included in the April 2021 ASHRAE Draft 118.2 are as
proposed in the March 2019 ASHRAE Draft 118.2 or have not been
changed in a way that their content affects the results of the test
procedure proposed in the March 2019 ASHRAE Draft 118.2.
---------------------------------------------------------------------------

As discussed previously in this document, DOE will adopt industry
test standards as DOE test procedures for covered products and
equipment, unless such methodology would be unduly burdensome to
conduct or would not produce test results that reflect the energy
efficiency, energy use, water use (as specified in EPCA) or estimated
operating costs of that equipment during a representative average use
cycle. 10 CFR part 430, subpart C, appendix A, Section 8(c). While DOE
would only consider adopting through incorporation by reference (IBR) a
finalized version of ASHRAE 118.2, DOE is interested in receiving
comments on the merits of the draft in anticipation of such a
possibility, or to consider incorporating aspects of the draft into a
revised DOE test procedure. The differences between the March 2019
ASHRAE Draft 118.2, the April 2021 ASHRAE Draft 118.2, and the DOE test
procedure are discussed in section III.B.2 of this NOPR.
1. ASHRAE 41.1
As stated previously, ASHRAE 41.1-1986 (RA 2006) was superseded by
ASHRAE 41.1-2013 and ASHRAE 41.1-2013 was superseded by ASHRAE 41.1-
2020. ASHRAE 41.1-2013 removed the aspirated wet bulb psychrometer
descriptions and stated they would be included in the next revision to
ASHRAE 41.6, ``Standard Method for Humidity Measurement.'' ASHRAE 41.6
was updated on July 3, 2014 and included the aspirated wet bulb
psychrometer descriptions that were removed in ASHRAE 41.1-2013. ASHRAE
41.1-2013 also added uncertainty analysis for temperature measurements,
information for thermistor-type devices, descriptions for thermopiles,
and reorganized the standard to be consistent with other ASHRAE
standards. ASHRAE 41.1-2020 added conditional steady-state test
criteria and further updated the standard to meet ASHRAE's mandatory
language requirements.
Section 3.2.1 of appendix E requires that temperature measurements
be made in accordance with ASHRAE 41.1-1986 (RA 2006), and section
3.2.2 of appendix E provides accuracy and precision requirements for
air dry bulb, air wet bulb, inlet and outlet water, and storage tank
temperatures. Sections 5.2.2.1 and 5.3.2 of appendix E effectively
require steady-state operation in which the flow-activated water heater
is operating at the maximum input rate, is supplied with water at a
temperature of 58 [deg]F <plus-minus>2 [deg]F, and delivers water at a
temperature of 125 [deg]F <plus-minus>5 [deg]F.
DOE reviewed ASHRAE 41.1-1986 (RA 2006), ASHRAE 41.1-2013, and
ASHRAE 41.1-2020 and found that the sections most relevant to appendix
E are the temperature measurement sections (i.e., sections 5 through 11
of ASHRAE 41.1-1986 (RA 2006), section 7 of ASHRAE 41.1-2013, and
section 7 of ASHRAE 41.1-2020) \24\ and the steady-state test criteria
added in ASHRAE 41.1-2020. The information in the temperature
measurement sections of the three versions of ASHRAE 41.1 examined does
not vary significantly. The additional steady-state test criteria of
ASHRAE 41.1-2020 varies significantly from and is more stringent than
\25\ the criteria specified in sections 5.2.2.1 and 5.3.2 of appendix
E; however, the appendix E criteria supersedes those in ASHRAE 41.1-
2020. DOE has tentatively determined that updating the reference of
ASHRAE 41.1-1986 (RA 2006) to the most recent version of the industry
standard (i.e., ASHRAE 41.1-2020) would not have a significant effect
on the test results, as the content of the relevant sections of the
ASHRAE 41.1 standards have not changed significantly and the new

[[Page 1568]]

content published in ASHRAE 41.1-2020 is superseded by appendix E. As
such, DOE proposes to update the reference of ASHRAE 41.1-1986 (RA
2006) to ASHRAE 41.1-2020. ASHRAE 41.1-2020 references ASHRAE 41.6-2014
and requires its use when measuring the wet bulb temperature. The wet
bulb temperature is required when testing heat pump water heaters to
appendix E and, therefore, DOE proposes to incorporate by reference
ASHRAE 41.6-2014.
---------------------------------------------------------------------------

\24\ Sections 5 through 11 of ASHRAE 41.1-1986 (RA 2006) were
combined into section 7 of ASHRAE 41.1-2013.
\25\ If adopted, section 5.5.3 of ASHRAE 41.1-2020 would be used
to determine steady-state operation within sections 5.2.2.1 and
5.3.2 of appendix E. Using this criteria, a flow-activated water
heater delivering water between 120 [deg]F and 121 [deg]F, which is
within the current delivery temperature range of 125 [deg]F <plus-
minus>5 [deg]F, would not be considered in steady-state due to the
difference in temperature between the average of the sample and the
set point temperature.
---------------------------------------------------------------------------

2. ASHRAE 118.2
a. Scope
Section 2 of the March 2019 ASHRAE Draft 118.2 defines the scope of
products covered by the industry test standard more narrowly than the
definitions for consumer water heaters and relevant commercial water
heater definitions contained in EPCA. For example, section 2 of the
March 2019 ASHRAE Draft 118.2 limits the storage volume for storage-
type water heaters to 120 gallons or less and limits the maximum
delivery temperature to 180 [deg]F (82 [deg]C), whereas EPCA does not
define limits on storage volume or maximum delivery temperature (42
U.S.C. 6291(27); 42 U.S.C. 6311(12)(A)-(B).
In the April 2020 RFI, DOE requested comment on whether the March
2019 ASHRAE Draft 118.2 test method could be applied to water heaters
beyond the scope defined in the March 2019 ASHRAE Draft 118.2 to cover
all water heaters included within the scope of DOE's definitions for
consumer water heaters and residential-duty commercial water heaters.
85 FR 21104, 21110 (April 16, 2020). And if modifications to the March
2019 ASHRAE Draft 118.2 would be required, DOE requested comment on
what those modifications should be. Id. CA IOUs and Rinnai expressed
their understanding that the March 2019 ASHRAE Draft 118.2 applies to
all water heaters within the current scope of DOE's test procedure. (CA
IOUs, No. 18 at p. 3; Rinnai, No. 13 at p. 5) A.O. Smith stated that
most aspects of the March 2019 ASHRAE Draft 118.2 could be applied to
water heaters beyond the scope defined in section 2 of the March 2019
ASHRAE Draft 118.2 with similar characteristics. (A.O. Smith, No. 20 at
p. 3) Rheem supported application of the March 2019 ASHRAE Draft 118.2
test method to cover a broader scope, including all water heaters
within DOE's definitions of consumer water heaters. However, Rheem
commented that modification may be required to address key differences,
along with validation testing of any changes. (Rheem, No. 14 at pp. 3)
The April 2021 ASHRAE Draft 118.2 did not propose changes to the
scope; therefore, section 2 of the April 2021 ASHRAE Draft 118.2 is the
same as the March 2019 ASHRAE Draft 118.2. DOE has tentatively reached
a similar conclusion as the commenters that the March 2019 ASHRAE Draft
118.2 and April 2021 ASHRAE Draft 118.2 could be applied to water
heaters that are outside of the scope found in section 2 of the March
2019 ASHRAE Draft 118.2 and within the scope of DOE's current consumer
water heater test procedure. As noted previously in this section, the
March 2019 ASHRAE Draft 118.2 scope limits the maximum rated storage
capacity at 120 gallons and the maximum delivery temperature at 180
[deg]F; whereas the scope prescribed by EPCA and the relevant
implementing regulations does not include these limits. Further, DOE
has found through testing that models with rated storage volumes above
120 gallons or that can deliver water above 180 [deg]F can be tested to
DOE's consumer water heater test procedure. Given the similarities
between the current DOE test procedure and the March 2019 ASHRAE Draft
118.2 and April 2021 ASHRAE Draft 118.2, such models could also be
tested using the ASHRAE test standard. Therefore, DOE has tentatively
determined that the test procedure presented in the March 2019 ASHRAE
Draft 118.2 and the April 2021 ASHRAE Draft 118.2 could be used to test
water heaters outside of the scope presented in section 2 of the March
2019 ASHRAE Draft 118.2.
b. Test Setup
Figures
Section 6 of the March 2019 ASHRAE Draft 118.2 includes new figures
that provide greater detail illustrating how to set up a water heater
for test. For example, a by-pass (purge) loop is added to the inlet
water line in Figures 1 through 8. Additional figures include: A test
set-up for a storage water heater with a side inlet water line and top
outlet water line; a test set-up for an instantaneous water heater with
connections on the top; the placement of a thermal break in the inlet
water line (the thermal break is added to the test set-up to prevent
heat from traveling up the inlet piping into the by-pass loop section,
as discussed in the next subsection); and two configurations for the
thermocouple tree if it needs to be installed through the outlet water
line.
In the April 2020 RFI, DOE requested feedback on whether the
figures in appendix E should be updated to include additional detail,
including the detail provided in the figures in the March 2019 ASHRAE
Draft 118.2. 85 FR 21104, 21110 (April 16, 2020). If thought to be
necessary, DOE asked that commenters address whether the additional
specificity provided in the figures could be too restrictive for the
purpose of the DOE test procedure, or whether such specificity would be
justified by improving reproducibility of test results. Id. AHRI, A.O.
Smith, CA IOUs, CSA, NEEA, Rheem, and Rinnai recommended that the
figures in appendix E be updated to include additional detail in
alignment with ASHRAE 118.2. (AHRI, No. 17 at p. 5; A.O. Smith, No. 20
at p. 3; CA IOUS, No. 18 at p. 3; CSA, No. 10 at p. 3; NEEA, No. 21 at
p. 6; Rheem, No. 14 at p. 4; Rinnai, No. 13 at p. 5) Rheem stated
further that the figures in the March 2019 ASHRAE Draft 118.2 represent
test set-up configurations that have been utilized by the AHRI contract
laboratories and were also developed through a best practices effort to
improve test consistency and repeatability across different labs.
(Rheem, No. 14 at p. 4) However, A.O. Smith suggested that any updates
to the figures in appendix E be used for reference only and not be
required, in order to avoid being overly restrictive. (A.O. Smith, No.
20 at p. 3)
Upon further comparison of the figures within the March 2019 ASHRAE
Draft 118.2 and appendix E, DOE found that the location in which the
inlet temperature is measured in figures 2A, 2B, and 3 of the March
2019 ASHRAE Draft 118.2 is different than in the corresponding figures
2 and 3 within appendix E. In the March 2019 ASHRAE Draft 118.2, the
inlet temperature is measured on the upstream side of the heat trap
formed by the U-bend in the required piping, while in appendix E the
inlet temperature measurement location is on the downstream side of the
U-bend. All figures in the March 2019 ASHRAE Draft 118.2 have the inlet
temperature location on the upstream side of the U-bend, while the
figures in appendix E vary depending on the type of water heater being
tested. Maintaining the same inlet temperature location for all water
heater types would simplify the test setup as compared to the current
requirements of appendix E. Further, given the short pipe distance
between the upstream and downstream side of the U-bend (on the order of
a few inches), it is unlikely that changing the location from the
downstream side to the upstream side would result in a measurable
difference in temperature.

[[Page 1569]]

However, DOE does not have adequate test data to fully understand the
effect that changing the location of the inlet temperature measurement
will have on test results and therefore is not proposing the use of the
inlet temperature locations specified in the March 2019 ASHRAE Draft
118.2. DOE welcomes information or data that may demonstrate any impact
of inlet temperature measurement location on energy efficiency results.
Thermal Break
Section 6 of the March 2019 ASHRAE Draft 118.2 includes new figures
that provide greater detail illustrating how to set up a water heater
for test. These additional figures include the installation location of
a thermal break in the inlet water line. Figure 9 of the March 2019
ASHRAE Draft 118.2 shows the thermal break installed in greater detail
than the other figures and provides more detail on the material
properties of the thermal break. The thermal break is added to the test
set-up to prevent heat from traveling up the inlet piping into the by-
pass loop section. When purging before a draw, any heat that is
transferred from the water heater through the inlet piping to the by-
pass loop section would be lost, as the by-pass loop is replenished
with cold supply water. The thermal break helps to prevent this heat
loss.
In the April 2020 RFI, DOE requested feedback on whether a
definition of ``thermal break'' \26\ should be added to its consumer
water heater test procedure. 85 FR 21104, 21110 (April 16, 2020). AHRI,
A.O. Smith, BWC, CSA, Keltech, NEEA, Rheem, and Rinnai supported the
addition of a definition for ``thermal break'' to the test procedure.
(AHRI, No. 17 at p. 5; A.O. Smith, No. 20 at p. 3; BWC, No. 12 at p. 2;
CSA, No. 10 at pp. 3; Keltech, No. 7 at p. 1; NEEA, No. 21 at p. 6;
Rheem, No. 14 at p. 4; Rinnai, No. 13 at p. 5) However, CEC argued that
there is no need to add the definition to the test procedure since the
definition can be incorporated by referencing a finalized version of
ASHRAE 118.2. (CEC, No. 11 at p. 2)
---------------------------------------------------------------------------

\26\ A ``thermal break'' is defined in the March 2019 ASHRAE
Draft 118.2 as a nipple made of material that has thermal insulation
properties (e.g., plastics) to insulate the by-pass loop from the
inlet piping. It should be able to withstand a pressure of 150 psi
and a temperature of 150 [deg]F.
---------------------------------------------------------------------------

In the April 2020 RFI, DOE requested feedback on the necessity of a
thermal break if no by-pass or purge loop is included in the test set-
up. 85 FR 21104, 21110 (April 16, 2020). AHRI, A.O. Smith, and Rinnai
stated that a thermal break should be included in the test set-up
regardless of whether there is a by-pass or purge loop. (AHRI, No. 17
at p. 5; A.O. Smith, No. 20 at p. 3; Rinnai, No. 13 at p. 5) CSA, NEEA,
and Rheem stated that a thermal break is not needed if no by-pass or
purge loop is present. (CSA, No. 10 at p. 4; NEEA, No. 21 at p. 6;
Rheem, No. 14 at p. 4)
Thermal breaks are not typically installed in the field. Therefore,
installation of a thermal break is not representative of an actual
installation configuration. The purpose of a thermal break is to
minimize unrepresentative effects of other parts of the test setup. A
by-pass loop is a method test labs use to ensure inlet water
temperatures are within the bounds of the test procedure (i.e., within
58 [deg]F <plus-minus>2 [deg]F by the first measurement of the draw,
which occurs at either 15 or 5 seconds from the start of draw when
testing to the first-hour rating or 24-hour simulated-use test,
respectively), but its inclusion in the test setup can create a
condition whereby a constant low temperature can remove energy from the
water heater at a higher rate than would be removed in the field. Heat
naturally travels through the inlet piping during standby, and the flow
rates and inlet temperatures required by the test procedure do not
always counteract this heating of the inlet piping before the required
inlet temperature measurements are taken. The addition of a thermal
break can help prevent these unrepresentative tank losses due to the
by-pass loop by creating a barrier between the highly conductive piping
materials. The inclusion of a thermal break in test setups that use a
by-pass loop would likely result in test results that are more
representative than a test setup with a by-pass loop and no thermal
break. However, use of a by-pass loop is not the only possible test
setup for meeting the test conditions within appendix E and it is
unclear the effect that requiring a thermal break in test setups would
have on the results from testing using a setup other than one employing
a by-pass loop. Absent such information DOE is not proposing to require
the use of a thermal break at this time. Therefore, DOE has tentatively
determined that a definition for ``thermal break'' is not necessary to
include, and DOE is not proposing one in this NOPR.
In the April 2020 RFI, DOE requested feedback on whether the
maximum temperature the thermal break must be able to withstand would
appropriately be set at 150 [deg]F, as is set in the March 2019 ASHRAE
Draft 118.2. 85 FR 21104, 21110 (April 16, 2020). AHRI, A.O. Smith,
BWC, CSA, Rheem, and Rinnai commented that a temperature of at least
150 [deg]F is an appropriate temperature for a thermal break to be able
to withstand. (AHRI, No. 17 at p. 5; A.O. Smith, No. 20 at p. 3; BWC,
No. 12 at p. 2; CSA, No. 10 at pp. 3-4; Rheem, No. 14 at p. 4; Rinnai,
No. 13 at p. 5-6) AHRI and BWC further commented that a thermal break
should be made of plastic or another material that is not thermally
conductive. (AHRI, No. 17 at p. 5; BWC, No. 12 at p. 2) Keltech stated
that thermal breaks should be able to withstand a maximum temperature
of at least 200 [deg]F, stating that 150 [deg]F might pose a problem
for water heaters capable of producing more than 125 [deg]F. (Keltech,
No. 7 at p. 1)
The thermal break is installed on the inlet water line, upstream of
the thermocouple measuring the inlet water temperature. DOE examined
its test data and found that, when water was not being drawn off, the
maximum temperature measured by the thermocouple measuring the inlet
water temperature never exceeded 100 [deg]F. Therefore, a thermal break
that is installed upstream of the thermocouple measuring the inlet
water temperature would not experience water temperatures exceeding 100
[deg]F. However, as stated previously, DOE is not proposing to require
the use of a thermal break and, as such, does not need to propose the
maximum temperature the thermal break must be able to withstand.
c. First-Hour Rating
Flow Rate
The April 2021 ASHRAE Draft 118.2 indicates that the flow rate for
water heaters with rated storage volumes less than 20 gallons would be
1.5 <plus-minus>0.25 gpm (5.7 <plus-minus>0.95 L/min). DOE has
identified consumer water heaters with storage volumes less than 20
gallons and with input rates near or at the maximum input rate
specified at 10 CFR 430.2 (i.e., water heaters with low volume and high
input rate). Section 5.3.3, ``First-Hour Rating Test'' of appendix E
requires that water heaters with a storage volume less than 20 gallons
be tested at 1.0 <plus-minus>0.25 gallons per minute (gpm) (3.8 <plus-
minus>0.95 liters (L)/minute (min)), as opposed to 3.0 <plus-minus>0.25
gpm (11.4 <plus-minus>0.95 L/min) required for water heaters with rated
storage volumes greater than or equal to 20 gallons. Water heaters with
low volume and high input rates can potentially operate indefinitely at
the 3.0 <plus-minus>0.25 gpm (11.4 <plus-minus>0.95 L/min) flow rate.
When tested as currently required by appendix E, such products would
have a measured FHR around 60 gallons (227 L) and, therefore, would be
required to use the medium draw pattern, although such models could be

[[Page 1570]]

used in applications similar to water heaters that are required to test
using the high draw pattern (e.g., flow-activated instantaneous water
heaters with high input rates and storage water heaters with greater
than 20 gallons stored water and high input rates and/or volumes). As
such, the current method of testing these products may not best
represent how they are used in the field.
In the April 2020 RFI, DOE requested feedback on the consumer water
heater test procedure with respect to testing the delivery capacity of
non-flow activated water heaters with low volume and high input rate.
85 FR 21104, 21114 (April 16, 2020). If amendments were thought to be
warranted, DOE requested comment on what method(s) would be appropriate
for determining the delivery capacity of such models and what
attributes can be used to distinguish these water heaters from non-flow
activated water heaters more appropriately tested by the FHR test. Id.
Rheem stated that there is a need to update the test procedure for
testing delivery capacity of non-flow activated water heaters with low
volume and high input rate. (Rheem, No. 14 at p. 9) DOE submitted a
comment on this issue to the March 2019 ASHRAE Draft 118.2, and a
solution was proposed in the April 2021 ASHRAE Draft 118.2 in which the
flow rate for water heaters with rated storage volumes less than 20
gallons would be 1.5 <plus-minus>0.25 gpm (5.7 <plus-minus>0.95 L/min)
instead of the 1.0 <plus-minus>0.25 gpm (3.8 <plus-minus>0.95 L/min)
currently specified in the consumer water heater test procedure. This
change would allow a water heater that can run continuously (i.e., low
volume and high input rate) to have a FHR that would correspond to the
high draw pattern. Further, lower capacity water heaters would not be
able to continuously deliver hot water at 1.5 gpm, which would result
in them continuing to be rated in a lower draw pattern.
DOE tested three electric storage water heaters with rated storage
volumes below 20 gallons to the current DOE FHR test (i.e., 1.0 <plus-
minus>0.25 gpm (3.8 <plus-minus>0.95 L/min)) and a FHR test at a flow
rate of 1.5 <plus-minus>0.25 gpm (5.7 <plus-minus>0.95 L/min). All
three electric storage water heaters are rated in the very small draw
pattern (i.e., they have low input rates). The three electric storage
water heaters were tested 4 times to each version of the FHR test
(i.e., 8 tests per unit and 24 tests total). The results of the tests
are shown in Table III.1.

Table III.1--Average First-Hour Rating Based on a Flow Rate of 1.0 gpm
and 1.5 gpm
------------------------------------------------------------------------
Average FHR at Average FHR at
Unit No. 1.0 gpm (3.8 L/ 1.5 gpm (5.7 L/ Change (%)
min) (gallons) min) (gallons)
------------------------------------------------------------------------
1....................... 7.3 7.5 +3.4
2....................... 6.4 6.2 -2.2
3....................... 6.9 7.2 +4.7
------------------------------------------------------------------------

As shown in Table III.1, changing the flow rate from 1.0 gpm to 1.5
gpm resulted in an average change in FHR between -2.2 percent and +4.7
percent. As the FHR rating did not increase above 10 gallons (i.e., the
threshold for determining whether to test to the very small or low draw
patterns during the 24-hour simulated-use test) when tested at 1.5 gpm,
the water heaters would continue to be tested to the very small draw
pattern when tested to the 24-hour simulated-use test.
Based on the testing of the three models, changing the flow rate
during the FHR test for water heaters with a rated storage volume less
than 20 gallons from 1.0 <plus-minus>0.25 gpm (3.8 <plus-minus>0.95 L/
min) to 1.5 <plus-minus>0.25 gpm (5.7 <plus-minus>0.95 L/min) would
have a relatively minimal impact on the FHR for water heaters with low
input rates, and the resultant FHR and associated draw pattern for the
24-hour simulated-use test would still be representative of the
expected use in the field. However, for water heaters with high input
rates the change in flow rate could significantly increase the FHR and
result in some models being tested and rated for UEF using a higher
draw pattern, which would provide ratings that are more representative
of their actual use. For these reasons, DOE is proposing to change the
flow rate during the FHR test for water heaters with a rated storage
volume less than 20 gallons from 1.0 <plus-minus>0.25 gpm (3.8 <plus-
minus>0.95 L/min) to 1.5 <plus-minus>0.25 gpm (5.7 <plus-minus>0.95 L/
min). This proposed change is also consistent with the April 2021
ASHRAE Draft 118.2, and, in development of the final rule, DOE will
consider the flow rate as finalized in the update to ASHRAE 118.2.
Initiation Criteria
The April 2021 ASHRAE Draft 118.2 includes additional criteria
defining the start of the FHR test, as compared to DOE's test
procedure. Section 5.3.3.3 of appendix E of the current DOE test
procedure states that prior to the start of the FHR test, if the water
heater is not operating (i.e., heating water), initiate a draw until
cut-in \27\ (i.e., when the water heater begins heating water). The
draw is then terminated any time after cut-in, and the water heater is
operated until cut-out.\28\ Once the maximum mean tank temperature is
observed after cut-out, the initial draw of the FHR test begins.
Section 7.3.3.3 of the April 2021 ASHRAE Draft 118.2 specifies that the
draw preceding the initial draw of the FHR test must proceed until the
outlet temperature drops 15 [deg]F below the maximum outlet temperature
observed, or until the draw time limit \29\ is reached. If the draw
time limit is reached before the outlet temperature drops 15 [deg]F
below the maximum outlet temperature observed, then the main heating
source of the water heater is shut off and the draw is continued until
the outlet temperature has dropped 15 [deg]F below the maximum outlet
temperature. Requiring the outlet temperature to drop 15 [deg]F below
the maximum outlet temperature may provide a more consistent starting
condition for the FHR test compared to the pre-conditioning method
specified in the current DOE test procedure because draws of varying
lengths can create different internal tank temperature profiles. Thus,
the additional requirement to tie the length

[[Page 1571]]

of the initial draw to a specific outlet temperature, which in some
cases would extend the draw length as compared to the current DOE test
procedure, could increase the repeatability of the FHR test.
---------------------------------------------------------------------------

\27\ ``Cut-in'' is defined in section 1 of appendix E as ``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.''
\28\ ``Cut-out'' is defined in section 1 of appendix E as ``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.''
\29\ The draw time limit is the rated storage capacity divided
by the flow rate times 1.2 (i.e., for a 75-gallon water heater the
draw time limit would be 30 minutes, or 75 gallons divided by 3 gpm
times 1.2).
---------------------------------------------------------------------------

The March 2019 ASHRAE Draft 118.2 specified two criteria for
terminating the water draw prior to the start of the FHR test: A 15
[deg]F drop in outlet temperature from the maximum outlet temperature
observed and a cut-in. The draft requirement for a cut-in was replaced
with the draw time limit in the April 2021 ASHRAE Draft 118.2.
In the April 2020 RFI, DOE requested feedback on whether the
addition of an outlet temperature drop criterion for terminating the
water draw prior to the start of the FHR test within the March 2019
ASHRAE Draft 118.2 is appropriate and/or necessary. 85 FR 21104, 21109
(April 16, 2020). If an outlet temperature drop criterion is
appropriate, DOE requested comment and data on whether 15 [deg]F is
sufficiently representative, given consumer expectation, or whether a
different threshold should be considered. Id. DOE also requested
information on any potential impact to the testing burden that would
result from an outlet temperature drop criterion. Id. Further, DOE
requested comment on how to address water heaters that would not meet
both initiation criteria (i.e., both a cut-in and an outlet temperature
drop) due to the ability to continuously deliver hot water at the
prescribed test conditions. Id. AHRI generally agreed that the 15
[deg]F drop is sufficiently representative. However, AHRI stated there
are oil-fired water heaters available that cannot achieve this
temperature drop. AHRI recommended that additional review and testing
be done to determine how to address water heaters that would not meet
both initiation criteria (i.e., the 15 [deg]F drop in outlet water
temperature and a cut-in). (AHRI, No. 17 at p. 4) A.O. Smith, BWC,
NEEA, Keltech, Rheem, and Rinnai agreed with AHRI's statements. (A.O.
Smith, No. 20 at p. 2; BWC, No. 12 at p. 3; Keltech, No. 7 at p. 1;
NEEA, No. 21 at p. 5; Rheem, No. 14 at p. 2; Rinnai, No. 13 at p. 3)
CSA stated that it is part of a working group for ASHRAE Draft 118.2 to
address this issue. (CSA, No. 10 at p. 2) NEEA stated that for water
heaters with enough output capacity to never drop 15 [deg]F, the FHR
test is not necessary, and the water heater should be tested to the Max
GPM test, even if the water heater is not technically flow-activated.
(NEEA, No. 21 at p. 5)
The combination of the 15 [deg]F drop in outlet water temperature
and the draw time limit criteria to the start of the FHR test would
provide a more repeatable pre-FHR draw, as the criteria to end the draw
would be explicitly stated (in contrast to the current test procedure,
which allows for any length of pre-FHR test draw, as long as a cut-in
occurs before the end of the draw). Because the pre-FHR test draw would
be more repeatable, the available energy content of the tank at the
start of the FHR test would be more consistent among different test
runs. In both the current DOE test procedure and the procedure in the
April 2021 ASHRAE Draft 118.2, the FHR test is initiated after a cut-
out from the recovery that occurs due to the pre-FHR test draw.
Therefore, in both cases, the water heater can be considered ``fully
heated'' and to have similar internal energy content, although
differences may be present due to the internal water temperature
gradient throughout the tank. However, it is unclear how these
differences in internal tank temperature will affect the test results.
Absent information as to the impact of the differences in internal tank
temperature on the test results, DOE is not proposing to amend appendix
E to include the pre-FHR test conditioning proposed in the April 2021
ASHRAE Draft 118.2.
Additionally, in the April 2020 RFI, DOE raised concerns over high
input rate water heaters that can heat water quicker than it is being
drawn off. 85 FR 21104, 21113-21114 (April 16, 2020). The solution \30\
presented in the April 2021 ASHRAE Draft 118.2 was the addition of a
draw time limit, which eliminates the chances of an indefinite water
draw. The procedure currently in appendix E \31\ also would not allow
an indefinite draw and, as stated previously, it is unclear the effect
the draw time limit proposal would have on test results. Therefore, DOE
is not proposing to include the draw time limit within appendix E.
---------------------------------------------------------------------------

\30\ The draw time limit solution was the result of the working
group in which CSA stated it was a part of. (CSA, No. 10 at p. 2)
\31\ Appendix E requires that the pre-FHR test draw be
terminated after the water heater initiates a recovery.
---------------------------------------------------------------------------

DOE agrees in principle with NEEA that the Max GPM test may provide
a representative value of delivery capacity and could be used to
determine the appropriate draw pattern of a water heater with a
sufficiently high input rate and low storage volume, despite not being
flow-activated. However, it is unclear at this time how these types of
non-flow activated water heaters could be separated from other non-flow
activated water heaters that are appropriately tested with the FHR test
and would be inappropriately tested with the Max GPM test.
Minimum Outlet Temperature
Section 7.3.3.3 of the March 2019 ASHRAE Draft 118.2 and section
7.3.3.4 of the April 2021 ASHRAE Draft 118.2 include additional
criteria regarding water draws during the FHR test, as compared to the
current DOE test procedure. The FHR test required in section 5.3.3 of
appendix E specifies a series of water draws over the course of one
hour. After each water draw is initiated, the draw is terminated when
the outlet water temperature decreases 15 [deg]F from the maximum
outlet water temperature measured during the draw. For example, if
after initiating a water draw, the outlet water temperature reaches a
maximum temperature of 125 [deg]F, the water draw would continue until
the outlet water temperature drops to 110 [deg]F, at which time the
water draw would be terminated. Section 7.3.3.4 of the April 2021
ASHRAE Draft 118.2 specifies that water draws during the FHR test
terminate if either: (1) The outlet water temperature decreases 15
[deg]F from the maximum outlet water temperature measured during the
draw, or (2) the outlet water temperature decreases to 105 [deg]F,
regardless of the maximum outlet water temperature measured during the
draw. Setting a minimum temperature threshold of 105 [deg]F would
reflect that in practice because consumers would likely stop drawing
water when it gets below 105 [deg]F, as the water would no longer be
considered ``hot.''
In the April 2020 RFI, DOE requested feedback on whether the
addition of a minimum outlet temperature as a criterion for terminating
draws during the FHR test is appropriate and/or necessary. 85 FR 21104,
21109 (April 16, 2020). If a minimum outlet temperature criterion is
appropriate, DOE requested comment and data on whether 105 [deg]F would
be sufficiently representative given consumer expectation, or whether a
different threshold should be considered. Id. DOE also requested
information on any potential impact this minimum outlet temperature may
have on testing burden. Id. BWC and NEEA supported the minimum outlet
temperature of 105 [deg]F for terminating draws of the FHR test. (BWC,
No. 12 at p. 2; NEEA, No. 21 at p. 5) Rheem supported a minimum outlet
temperature, but suggested a 100 [deg]F limit would be more appropriate
and would better represent usable hot water temperatures, especially
when considering electric water heaters used for point-of-use, such as
handwashing applications. (Rheem, No. 14 at p. 3)

[[Page 1572]]

AHRI and Rinnai stated that a 15 [deg]F drop in outlet temperature or
105 [deg]F minimum outlet temperature, whichever is higher, would be
sufficiently representative. (AHRI, No. 17 at p. 4; Rinnai, No. 13 at
p. 4) A.O. Smith and Rheem suggested more testing and investigation are
necessary before any decisions are made. (A.O. Smith, No. 20 at p. 2;
Rheem, No. 14 at p. 3) CSA stated that, when testing to the March 2019
ASHRAE Draft 118.2, all draws would be terminated at 105 [deg]F
regardless of outlet temperature, but stated that this can potentially
create a bias for conducting the procedure at the higher end of 125
<plus-minus>5 [deg]F tolerance. CSA further stated that some water
heaters start stacking \32\ after the first draw, resulting in the
outlet temperature going above 130 [deg]F during the FHR test, and
questioned how that would affect the overall FHR and draw pattern bin.
(CSA, No. 10 at p. 2)
---------------------------------------------------------------------------

\32\ ``Stacking'' refers to when a storage water heater has hot
water within the storage tank that is well above the temperature
that is typically stored, which can result from successive short
duration draws in a short amount of time. During typical operation,
a draw removes hot water from the top of the storage tank, and the
removed water is replaced with cold water that enters near the
bottom the tank. The thermostat that controls the burner or element
operation is also located near the bottom of the tank. Repeated
short-duration draws result in multiple ``bursts'' of cold water
entering the bottom of the tank; however, because the draws are
short-duration, the total amount of water drawn is relatively small,
and the temperature at the top of the tank may remain ``hot'' at the
target setpoint. These short bursts of cold water entering near the
thermostat may trigger a cut-in, and the water heater will begin
heating despite the temperature at the top of the tank still being
hot at the target setpoint. As the already-hot tank is being heated
further, the temperature within the tank increases above the
temperature that the water heater typical operates.
---------------------------------------------------------------------------

Based on a review of existing test data, the 105 [deg]F outlet
temperature criteria would affect only a small number of tests, if any.
The test currently requires that the draw be terminated after a 15
[deg]F drop in outlet temperature, and the outlet temperature is
required to be between 120 [deg]F and 130 [deg]F when setting the
thermostat. Therefore, the outlet temperature is unlikely to be below
105 [deg]F during the test, as most draws should terminate before that
point. The maximum outlet temperature of the draw would have to be
below 120 [deg]F for the 105 [deg]F criteria to be triggered. As a
result, DOE understands CSA's comment that all draws will be terminated
at 105 [deg]F, if tested to ASHRAE Draft 118.2, to be incorrect.
Section 7.3.3.4 of the April 2021 ASHRAE Draft 118.2 includes a
statement that requires the draw be terminated at 105 [deg]F or when
the outlet temperature is 15 [deg]F below the maximum outlet
temperature measured during the draw, ``whichever is higher.''
Therefore, if the maximum outlet temperature of a draw was 125 [deg]F,
for example, then the draw would end after a 15 [deg]F drop, or once
the outlet water temperature is 110 [deg]F, which is higher than 105
[deg]F. Also, Rheem's suggestion of a 100 [deg]F limit to address
handwashing water heaters would not be appropriate for water heaters
generally and would be more appropriately addressed as part of
development of a method to appropriately test such water heaters (see
section III.C.7). DOE is not proposing to add the 105 [deg]F minimum
outlet temperature criteria to the FHR test draw termination criteria,
as further test data is needed to assess the effect on the FHR test
results.
Scaling of the Last Draw Volume
Section 5.3.3.3 of appendix E includes a provision for the FHR test
requiring that if the final draw is not initiated prior to one hour
from the start of the test, then a final draw is imposed at the elapsed
time of one hour. In this situation, calculations presented in section
6.1 of appendix E are used to determine the volume drawn during the
final draw for purposes of calculating FHR. The volume of the final
draw is scaled based on the temperature of the water delivered during
the final draw as compared to the temperature of the water delivered
during the previous draw. The calculated final draw volume is added to
the total volume drawn during the prior draws to determine the FHR. The
April 2021 ASHRAE Draft 118.2 does not include a final draw volume
scaling calculation for the case in which a draw is not in progress at
one hour from the start of the test and a final draw is imposed at the
elapsed time of one hour. Instead, the April 2021 ASHRAE Draft 118.2
method calculates FHR as the sum of the volume of hot water delivered
without any scaling of the final draw.
The methodology for conducting the FHR test, and in particular the
issue of whether to scale the final draw, was considered by DOE in a
final rule that was published on May 11, 1998 (May 1998 final rule). In
the May 1998 final rule, DOE determined that scaling the final draw
volume based on the outlet water temperature was appropriate and was
included to adjust the volume of the last draw to account for the lower
heat content of the last draw compared to the earlier draws with fully
heated water. 63 FR 25996, 26004-26005 (May 11, 1998).
In the April 2020 RFI, DOE requested comment on whether the scaling
of final draw volume should be maintained as part of the FHR
calculation, in the case that a draw is not initiated prior to one hour
from the start of the test but is imposed at that time before the water
has been heated to the specified temperature to initiate the draw. 85
FR 21104, 21111 (April 16, 2020). DOE further requested feedback on the
effect that removing the scaling of the final draw volume would have on
the rated FHR, draw pattern, and rated UEF values of the various types
of non-flow activated water heaters that are tested to the FHR test.
Id. In response, AHRI, A.O. Smith, BWC, Rheem, Rinnai, and SMTI
suggested that DOE remove the final draw volume scaling calculation,
which would be consistent with the March 2019 ASHRAE Draft 118.2.
(AHRI, No. 17 at p. 6; A.O. Smith, No. 20 at p. 3; BWC, No. 12 at p. 3;
Rheem, No. 14 at p. 5; Rinnai, No. 13 at p. 6; SMTI, No. 19 at p. 3)
AHRI, A.O. Smith, Rinnai, and Rheem further stated that removing the
final draw volume scaling would have minimal impact on the rated FHR,
draw pattern, and rated UEF values. (AHRI, No. 17 at p. 6; A.O. Smith,
No. 20 at p. 3; Rinnai, No. 13 at p. 6; Rheem, No. 14 at p. 5) CSA
stated that the current final draw volume scaling method should be
maintained and that a water heater delivering water at 106 [deg]F
should not be equal to a water heater delivering water at 110 [deg]F.
According to CSA, the outlet water temperatures would most likely be
tempered by the end user, and the water heater delivering 110 [deg]F
water would supply more tempered water than a water heater delivering
106 [deg]F, even though the volume of the last draw, as measured, would
be roughly the same. CSA stated further that removing the scaling of
the final draw volume could possibly move water heaters to the next
highest draw pattern. (CSA, No. 10 at p. 5)
The scaling of the final draw accounts for the possible lower heat
content of the last draw as compared to earlier draws. The test
procedure specifies a constant flow rate throughout testing. The flow
rate is fixed, and, as water is drawn, the water temperature decreases.
In practice, water used by the consumer is typically at a lower
temperature than is delivered by the water heater (i.e., water drawn
from the water heater is mixed with water from the cold tap). The flow
rate of water delivered to the consumer by a faucet or showerhead is
fixed by the faucet or showerhead. As the heat content of the water
delivered by the water heater decreases, the flow rate of water from
the water heater is increased to maintain the temperature of the mixed
water delivered by the faucet

[[Page 1573]]

or showerhead (i.e., in practice, as water temperature decreases, the
flow rate of water from the water heater is increased). Thus, DOE has
tentatively determined that scaling the final draw volume based on
outlet temperature is more representative of the actual use in the
field.
Further, removing the scaling of the final draw volume would result
in many FHR values having to be recertified as many models have the
final draw imposed at the one-hour mark (only those models that
initiated their final draw prior to 1 hour would not be affected).
Because the change is to the calculation of FHR only, retesting would
not be needed unless the resulting FHR value required a new 24-hour
simulated-use test due to a change in the applicable draw pattern bin
(e.g., if the FHR increases such that a model moves from the medium to
the high draw pattern). DOE agrees with commenters that most models
would not require a new 24-hour simulated-use test. However, any
retesting would be a burden on manufacturers and, as stated previously,
removing the scaling provisions would result in a less representative
test.
Removing or amending the scaling of the final draw volume would
change the FHR value, which could change the required draw pattern to
use for the simulated-use test, as defined in section 5.4.1 of appendix
E. The current draw pattern thresholds were determined based on the
current final draw scaling methodology, and are therefore
representative of actual use only when used with FHR values based on
the current final draw scaling methodology. Removing or amending the
scaling of the final draw volume could require adjusting the draw
pattern thresholds to ensure that the applicable draw patterns (based
on FHR value thresholds) remain representative of actual use.
The FHR metric is a method to compare the amount of usable water
that a water heater can produce in a given amount of time. As long as
the metric is applied consistently throughout the market, the consumer
can use it to make comparisons among different models. Removing the
scaling of the final draw volume may increase test burden on some
manufacturers while resulting in a less representative test, and could
require an update to the draw pattern thresholds. As described, changes
to the draw pattern threshold could result in water heaters being
classified in a lower draw pattern than they are currently, and it is
uncertain as to the extent the reclassification would result in a test
procedure that is representative for such models. Therefore, DOE has
tentatively determined not to remove or amend the scaling of the final
draw volume.
In response to the April 2020 RFI, SMTI stated that, if the scaling
of the final draw volume was maintained, the equation should be amended
to use the inlet water temperature as opposed to the minimum outlet
temperature of the previous draw. According to SMTI, this change would
make the overall calculation more representative of the energy
availability in the final draw. (SMTI, No. 19 at p. 3-4) However, while
basing the scaling calculation on inlet water temperature as opposed to
outlet water temperature would be more representative of the energy
availability in the tank, it would not be more representative of the
energy availability in the final draw. The energy that is useful to the
consumer is based on the energy of water delivered at a temperature at
or above the consumer's desired temperature. The consumer's desired
temperature is approximated in the FHR test by the minimum delivery
temperature of the draw and not the inlet water temperature. Therefore,
DOE has tentatively determined that scaling the final draw volume based
on the inlet water temperature would result in a less representative
test and a metric that could mislead the consumer as to how much hot
water they actually have available. Further, the change suggested by
SMTI to base the scaling of the final draw volume on inlet water
temperature would result in a FHR value that is higher than under the
current DOE test procedure, but to a lesser degree than if the
temperature scaling were removed. As stated, DOE has tentatively
determined that amending scaling of the final draw volume to use the
inlet water temperature as opposed to the minimum outlet water
temperature would result in a less representative test and, therefore,
DOE is not proposing this change.
d. 24-Hour Simulated-Use Test
Initiation Criteria
Similar to the initiation criteria discussed in section III.B.2.c
for the FHR test, section 7.4.2 of the April 2021 ASHRAE Draft 118.2
includes criteria for a pre-24-hour simulated-use test draw, which ends
after either the outlet temperature drops by 15 [deg]F or the draw time
limit is reached. Section 5.4.2 of appendix E currently requires that
the water heater sit idle for 1 hour prior to the start of the 24-hour
simulated-use test; during which time no water is drawn from the unit
and no energy is input to the main heating elements, heat pump
compressor, and/or burners. Appendix E provides no instruction on how
to condition the tank prior to this one hour. However, as discussed in
section III.B.2.c, it is unclear how the outlet temperature drop
criteria and the draw time limit will affect the internal tank
temperature at the start of the 24-hour simulated-use test and how this
difference in internal tank temperatures will affect the test results.
Therefore, DOE is not proposing to amend appendix E to include the
preconditioning proposed in the April 2021 ASHRAE Draft 118.2. DOE
welcomes data that provide information regarding the impact of the
preconditioning provisions in the April 2021 ASHRAE Draft 118.2 on the
UEF result.
Recovery Efficiency
Section 8.3.2 of the March 2019 ASHRAE Draft 118.2 includes
language specifying that, when the first recovery of the 24-hour
simulated-use test ends during a draw, the first recovery period
extends until the end of that draw. The first recovery period is used
in section 8.3.2 of the March 2019 ASHRAE Draft 118.2 and section 6.3.2
of appendix E to calculate recovery efficiency. DOE's test procedure
does not explicitly address how to calculate recovery efficiency if the
first recovery period ends during a draw. A recovery period is defined
in section 1 of appendix E as ``the time when the main burner of a
storage water heater is raising the temperature of the stored water.''
Each of the parameters in the recovery efficiency equation are recorded
from the ``beginning of the test to the end of the first recovery
period following the first draw.'' The DOE test procedure does not
explicitly state whether values are recorded at the end of the recovery
period that ends after the initiation of the first draw, or at the end
of a recovery period that occurs after the end of the first draw.
In the April 2020 RFI, DOE requested feedback on whether additional
specification should be added to appendix E addressing the first
recovery period ending during a draw. 85 FR 21104, 21111 (April 16,
2020). DOE further requested that if extending the first recovery
period to the end of the draw is thought to be appropriate, whether the
test procedure should also address the situation where a second
recovery is initiated prior to the ending of the draw. Id. DOE also
requested how to appropriately find the maximum mean tank temperature
after cut-out following the recovery period. Id. AHRI, A.O. Smith, CSA,
Rheem, and Rinnai generally supported adding a specification in
appendix E to address the first recovery period ending during a draw.
(AHRI, No. 17 at p. 7; A.O.

[[Page 1574]]

Smith, No. 20 at p. 3; CSA, No. 10 at p. 5; Rheem, No. 14 at p. 5;
Rinnai, No. 13 at p. 7) AHRI, A.O. Smith, Rheem, and Rinnai supported
extending the first recovery period to the end of the draw to include
all water heater activity up to and including the end of the draw.
(AHRI, No. 17 at p. 7; A.O. Smith, No. 20 at p. 3; Rheem, No. 14 at p.
5; Rinnai, No. 13 at p. 7) AHRI and Rheem recommended that the maximum
mean tank temperature just after the first cut-out be used. (AHRI, No.
17 at p. 7; Rheem, No. 14 at p. 5) CSA recommended that for the other
scenarios outlined by DOE, testing should be conducted to determine the
proper procedure. (CSA, No. 10 at p. 5) No comments were received
directly addressing the issue of when a second recovery starts prior to
the end of the draw in which the first recovery ended.
The situation in which a recovery ends during a draw likely occurs
during draws with a low enough flow rate that the water heater can heat
water more quickly than the draw is removing. The energy used for the
recovery efficiency calculation includes energy used to heat water and
auxiliary energy; therefore, the energy associated with the first
recovery period should represent the entire draw to capture all energy
use. Commenters generally agreed that the maximum mean tank temperature
measured after the recovery should be right after cut-out (i.e., in the
middle of the draw). After cut-out, as the draw continues, the mean
tank temperature will drop as heated water is replaced by cold inlet
water; therefore, the mean tank temperature immediately after cut-out
will be the maximum observed. As such, DOE proposes to explicitly
provide that when the first recovery ends during a draw, the first
recovery period is extended to the end of the draw and the mean tank
temperature measured immediately after cut-out is used as the maximum
mean tank temperature value in the recovery efficiency calculation.
On January 31, 2020, DOE published a Notice of Decision and Order
\33\ (Decision and Order) by which a test procedure waiver for certain
basic models was granted to address the issue of a second recovery
initiating during the draw during which the first recovery ended. 85 FR
5648. The Decision and Order prescribes an alternate test procedure
that extends the first recovery period to include both the first and
second recoveries. Id. at 85 FR 5652. In the context of the Decision
and Order, DOE determined that the consideration of delivered water
mass and inlet and outlet temperatures until the end of the draw is
appropriately representative, and, therefore, the entire energy used
from both recoveries is included. Id. at 85 FR 5651-5652.
---------------------------------------------------------------------------

\33\ Notice of Decision and Order in response to BWC petition
for waiver is available at: <a href="http://www.regulations.gov/document?D=EERE-2019-BT-WAV-0020-0008">www.regulations.gov/document?D=EERE-2019-BT-WAV-0020-0008</a>.
---------------------------------------------------------------------------

In the April 2020 RFI, DOE requested feedback on whether the
equation for recovery efficiency for water heaters with a rated storage
volume greater than or equal to 2 gallons (7.6 L) should be updated to
address when the recovery period lasts for more than one draw. 85 FR
21104, 21111 (April 16, 2020). CSA, EEI, NEEA, Rheem, and Rinnai
recommended that DOE update the recovery efficiency calculation to
account for the period extending beyond one draw to increase clarity.
(CSA, No. 10 at p. 5; EEI, No. 8 at p. 4; NEEA, No. 21 at p. 6; Rheem,
No. 14 at p. 6; Rinnai, No. 13 at p. 7) This change was presented in
the March 2019 ASHRAE Draft 118.2 and is in the Notice of Decision and
Order. 85 FR 5648, 5652 (Jan. 31, 2020). Consistent with the published
Notice of Decision and Order and as supported by commenters, DOE
proposes to update the recovery efficiency equation to specify
accounting for the mass of water drawn for all draws initiated during
the recovery period. As such, DOE is proposing to amend appendix E
consistent with the alternate test procedure in the Decision and Order.
Standby Period
Appendix E includes a standby \34\ period measured between the
first and second draw clusters,\35\ during which data is recorded that
is used to calculate the standby heat loss coefficient. See section
5.4.2 of appendix E. Sections 7.4.2.1 and 7.4.2.2 of the March 2019
ASHRAE Draft 118.2 and sections 7.4.3.1 and 7.4.3.2 of the April 2021
ASHRAE Draft 118.2 add a condition that the standby period data can be
recorded between the first and second draw clusters only if the time
between the observed maximum mean tank temperatures after cut-out
following the first draw cluster to the start of the second draw
cluster is greater than or equal to 6 hours. Otherwise, the standby
period data would be recorded after the last draw of the test. This
condition would provide a sufficiently long standby period to determine
standby loss, which might make this calculation more repeatable and the
results more representative of standby losses experienced in an average
period of use. However, this might also cause the test to extend beyond
a 24-hour duration.
---------------------------------------------------------------------------

\34\ ``Standby'' is defined in section 1.12 of appendix E as
``the time, in hours, during which water is not being withdrawn from
the water heater.''
\35\ A ``draw cluster'' is defined in section 1 of appendix E as
``a collection of water draws initiated during the 24-hour
simulated-use test during which no successive draws are separated by
more than 2 hours.'' There are two draw clusters in the very small
draw pattern and three draw clusters in the low, medium, and high
draw patterns.
---------------------------------------------------------------------------

In the April 2020 RFI, DOE requested feedback on whether it should
consider the addition of a minimum standby period length of 6 hours for
use in the standby loss calculations, and on the appropriateness of
recording this data after the final draw cluster when less than 6 hours
of standby time occur between the first and second draw clusters. 85 FR
21104, 21110 (April 16, 2020). BWC stated that DOE should adopt a
minimum standby period length of 6 hours for use in the standby loss
calculation. (BWC, No. 12 at p. 3) NEEA stated that DOE should reduce
the standby period to 4 hours, as it believed the increased burden to
require a 6-hour standby period would be unwarranted. (NEEA, No. 21 at
p. 4) AHRI and Rheem stated they do not support the addition of a
minimum standby period length of 6 hours because it would extend the
total test period time to over 24 hours. (AHRI, No. 17 at p. 6; Rheem,
No. 14 at p. 4) A.O. Smith stated that adding 6 hours to the test would
be significant and recommended that DOE investigate whether the
addition is truly necessary, or if a less burdensome method could
achieve the same goal. (A.O. Smith, No. 20 at p. 3) CSA referenced its
test data, which included units with a standby period ranging from 5
minutes to over 7 hours, to demonstrate that standby time has very
little effect on the overall UEF value. (CSA, No. 10 at p. 4)
The standby heat loss coefficient (i.e., UA) is calculated from
data recorded during the standby period. DOE reviewed its available
test data and found that for the models reviewed, UA has very little
effect on UEF, which is consistent with CSA's comment. UA is used only
to adjust the daily water heating energy consumption to the nominal
ambient temperature of 67.5 [deg]F (19.7 [deg]C). Given that the
ambient temperature range is relatively narrow (i.e., 65 [deg]F to 70
[deg]F (18.3 [deg]C to 21.1 [deg]C)), the adjustment has only a minimal
impact on the daily water heating energy consumption. Further, DOE
found that the length of the recovery period has little effect on the
resulting UA value. Therefore, DOE has tentatively determined that
requiring a 6-hour standby period would not affect UA and UEF enough to
justify the increased test burden associated with a

[[Page 1575]]

test that already could last longer than 24 hours.
Last Hour
In the April 2020 RFI, DOE requested feedback on whether it should
consider an alternate procedure, like that in section 7.4.2.2 of the
March 2019 ASHRAE Draft 118.2 (and section 7.4.3.2 of the April 2021
ASHRAE Draft 118.2), for the last hour of the 24-hour simulated-use
test. 85 FR 21104, 21111 (April 16, 2020). DOE further requested
feedback on whether the addition of standby loss in the total energy
use calculation adequately represents the auxiliary energy use that is
not measured between the minute prior to the start of the recovery
occurring between hours 23 and 24, and hour 24 of the 24-hour
simulated-use test. Id.
CSA requested that DOE revisit the procedure for the last hour of
the 24-hour simulated-use test. CSA raised a number of questions with
how the test procedure in section 5.4.2, Test Sequence for Water
Heaters with Rated Storage Volumes Greater Than or Equal to 2 Gallons,
is implemented, specifically with regard to when power is to be turned
off and on. (CSA, No. 10 at p. 4)
Although not stated explicitly in section 5.4.2 of appendix E, in
the case that the standby period is between the first and second draw
clusters, power to the main burner, heating element, or compressor is
disabled during the last hour of the 24-hour simulated-use test. In the
case that the standby period is after the last draw of the 24-hour
simulated-use test, power to the main burner, heating element, or
compressor is not disabled.
Section 5.4.2 of appendix E states that during the last hour of the
24-hour simulated-use test, power to the main burner, heating element,
or compressor shall be disabled; at 24 hours, record the reading given
by the gas meter, oil meter, and/or the electrical energy meter as
appropriate; and determine the fossil fuel and/or electrical energy
consumed during the entire 24-hour simulated-use test and designate the
quantity as Q.
Section 5.4.2 of appendix E also provides that in the case that the
standby period is after the last draw of the 24-hour simulated-use
test, an 8-hour standby period is required, and this period may extend
past hour 24. The procedures for the standby period after the last draw
of the 24-hour simulated-use test allow for a recovery to occur at the
end of the 8-hour standby period, which indicates that the power to the
main burner, heating element, or compressor is not disabled. DOE's
procedure as described may result in some confusion. Further, the
method of determining the total energy use during the 24-hour
simulated-use test, Q, and total test time are not explicitly stated
for when a standby period occurs after the last draw of the 24-hour
simulated-use test. As discussed in the following paragraphs, DOE is
proposing to amend the procedures for the last hour of the 24-hour
simulated-use test to explain how to end the test for both standby
period scenarios.
CSA and NEEA stated that DOE should adopt the March 2019 ASHRAE
Draft 118.2 approach. (CSA, No. 10 at p. 4; NEEA, No. 21 at p. 6)
In the March 2019 ASHRAE Draft 118.2 and April 2021 ASHRAE Draft
118.2, power is not disabled when the standby period occurs after the
last draw of the test. But, if a recovery occurs between an elapsed
time of 23 hours following the start of the test (hour 23) and 24 hours
following the start of the test (hour 24), the following alternate
approach is applied to determine the energy consumed during the 24-hour
simulated-use test: The time, total energy used, and mean tank
temperature are recorded at 1 minute prior to the start of the recovery
occurring between hour 23 and hour 24, along with the average ambient
temperature from 1 minute prior to the start of the recovery occurring
between hour 23 and hour 24 to hour 24 of the 24-hour simulated-use
test. These values are used to determine the total energy used by the
water heater during the 24-hour simulated-use test. This alternate
calculation combines the total energy used 1 minute prior to the start
of the recovery occurring between hours 23 and 24 and the standby loss
experienced by the tank during the time between the minute prior to the
recovery start and hour 24. This provision in section 7.4.2.2 of the
March 2019 ASHRAE Draft 118.2 and section 7.4.3.2 of the April 2021
ASHRAE Draft 118.2 does not require the water heater to be de-energized
during the standby period. Disabling power to the water heater is
typically a manual operation that requires the presence of a
technician. In cases where the technician does not disable power at the
correct time, a retest of the 24-hour simulated-use test may be
necessary. To the extent this draft provision would eliminate the need
to ensure that a unit is switched off for the last hour of the 24-hour
simulated-use test, it could reduce test burden.
In response to the April 2020 RFI, CSA further stated that not
including the pilot energy does not adequately represent auxiliary
energy usage for water heaters with continuously burning pilot lights.
(CSA, No. 10 at p. 5) DOE notes that in the last hour of the 24-hour
simulated-use test, the power to the main burner is disabled. In
practice, cutting off the gas flow to the main burner disables the
pilot light as well. However, disabling power to the main burner could
also be accomplished by reducing the thermostat setting to the minimum
setting available, which would result in the water heater under test
not initiating a recovery during the last hour and gas continuing to be
supplied to the pilot light. Reducing the thermostat setting would be a
manual operation performed by a technician, not an automated action,
which increases the chances of an invalid test. CSA also stated that
water heaters without standing pilots will have minimal energy
consumption in the last hour compared to the overall energy
consumption, and that the total energy use calculation adequately
represents the auxiliary energy use for these water heaters. Id. AHRI
and A.O. Smith stated that they are in the process of evaluating the
March 2019 ASHRAE Draft 118.2 test procedure for the last hour of the
24-hour simulated-use test and will provide additional information
after their evaluation is completed. (AHRI, No. 17 at p. 6; A.O. Smith,
No. 20 at p. 3) Rheem stated that given the limited time for evaluation
and testing of an alternate procedure, the current procedure for the
last hour of the 24-hour simulated-use test in appendix E should be
maintained. (Rheem, No. 14 at p. 5)
At this time, DOE has not been provided with the additional
information from AHRI or A.O. Smith regarding the procedure for the
last hour of the 24-hour simulated-use test, and agrees with Rheem that
further evaluation of the alternate procedure presented in the March
2019 ASHRAE Draft 118.2 and April 2021 ASHRAE Draft 118.2 should be
conducted before a determination is made. As stated previously, the
procedure for the last hour of the 24-hour simulated-use test may
benefit from further, more explicit instruction, and DOE proposes to
explicitly state how to end the test depending on whether the standby
period is between draw clusters 1 and 2 or after the last draw of the
test.

C. Test Procedure Requirements

1. Commercial Water Heater Draw Pattern
In response to the April 2020 RFI, EEI suggested DOE consider a
definition and test procedure for consumer water heaters used in
commercial settings. EEI suggested that the test procedure would

[[Page 1576]]

include a daily water draw (i.e., draw pattern) that is greater than
the ``high'' draw pattern, which is the draw pattern with the largest
amount of delivered water in the test procedure for consumer water
heaters. (EEI, No. 8 at p. 3)
DOE has tentatively determined not to add a draw pattern with a
delivered volume greater than the high draw pattern in appendix E,
which would represent consumer water heaters installed in commercial
applications. Under 42 U.S.C. 6293(b)(3), in relevant part, any test
procedures prescribed or amended shall be reasonably designed to
produce test results which measure energy efficiency of a covered
product during a representative average use cycle or period of use.
Consumer water heaters are designed for use in residential applications
and, as such, a draw pattern representative of a commercial
installation would not be representative of the product's average use
cycle or period of use.
2. Terminology
In sections 5.3.3.1 and 5.3.3.2 of appendix E, which describe
general requirements and draw initiation criteria, respectively, for
the FHR test, the term ``storage-type water heaters'' is used. However,
the FHR test applies to all water heaters that are not flow-activated,
which includes non-flow activated instantaneous water heaters. In the
April 2020 RFI, DOE requested feedback on whether to update the phrase
``storage-type water heaters'' in section 5.3.3 to ``non-flow activated
water heaters.'' 85 FR 21104, 21112 (April 16, 2020). AHRI, Keltech,
Rheem, and Rinnai stated that there is no need to change the phrase
``storage-type water heaters'' in section 5.3.3. (AHRI, No. 17 at p. 9;
Keltech, No. 7 at p. 1; Rheem, No. 14 at p. 7; Rinnai, No. 13 at p. 9)
AHRI stated that if instantaneous water heaters are properly
classified, this issue would be resolved (AHRI, No. 17 at p. 9).
DOE submitted a comment to the March 2019 ASHRAE Draft 118.2 that
suggested changing the language within sections 7.3.3.1 and 7.3.3.2
from ``storage-type'' to ``non-flow activated.'' This proposed change
was accepted by the ASHRAE 118.2 committee and is present in section
7.3.3.1 of the April 2021 ASHRAE Draft 118.2. Section 7.3.3.2 was not
included in the April 2021 ASHRAE Draft 118.2. In an effort to align
terminology with that recognized by industry in proceedings subsequent
to the April 2020 RFI, DOE proposes to change the phrase ``storage-
type'' to ``non-flow activated'' within sections 5.3.3.1 and 5.3.3.2 of
appendix E and further proposes to change ``storage-type'' and
``instantaneous-type'' to ``non-flow activated'' and ``flow-
activated,'' respectively, throughout appendix E. This change would be
a clarification only and would not change the current application of
sections 5.3.3.1 and 5.3.3.2 of appendix E.
In section 6.3.3 of appendix E, titled ``Hourly Standby Losses,''
the descriptions for cumulative energy consumption (Q<INF>su,0</INF>
and Q<INF>su,f</INF>) \36\ and mean tank temperature
(T<INF>su</INF>,<INF>0</INF> and T<INF>su,f</INF>,) at the start and
end of the standby period, along with the elapsed time, average storage
tank temperature, and average ambient temperature over the standby
period ([tau]<INF>stby,1</INF>, T<INF>t,stby</INF>,<INF>1</INF>, and
T<INF>a,stby,1</INF>, respectively) \37\ specifically refer to the
standby period that would occur after the first draw cluster, but do
not explicitly address the case where the standby period occurs after
the last draw of the test.
---------------------------------------------------------------------------

\36\ The subscript ``su,0'' refers to the start of the standby
period in which the standby loss coefficient is determined, and the
subscript ``su,f'' refers to the end of this standby period.
\37\ The subscript ``stby,1'' refers to the standby period in
which the standby loss coefficient is determined. The subscripts
``t'' and ``a'' refer to the mean tank temperature and ambient
temperature, respectively.
---------------------------------------------------------------------------

In the April 2020 RFI, DOE requested feedback on whether it should
revise the descriptions of Q<INF>su,0</INF>, Q<INF>su,f</INF>,
T<INF>su</INF>,<INF>0</INF>, T<INF>su,f</INF>, [tau]<INF>stby,1</INF>,
T<INF>t,stby</INF>,<INF>1</INF>, and T<INF>a,stby,1</INF> to explicitly
include cases where the standby period occurs after the last draw of
the test, in addition to cases where the standby period occurs after
the first draw cluster. 85 FR 21104, 21113 (April 16, 2020). AHRI, A.O.
Smith, CSA, and Rheem recommended not changing the descriptions. (AHRI,
No. 17 at p. 10; A.O. Smith, No. 20 at p. 5; CSA, No. 10 at p. 8;
Rheem, No. 14 at p. 8) BWC observed inconsistences in definitions of
the variables in the current test procedure in sections 1.13 and 6.3.3
and stated further that many of these can be addressed by adopting the
descriptions in the March 2019 ASHRAE Draft 118.2. (BWC, No. 12 at p.
6)
Within appendix E, the standby loss period could occur at multiple
points in the test, depending on the operation of the water heater
under test, but, as described previously, the descriptions of these
variables (Q<INF>su,0</INF>, Q<INF>su,f</INF>,
T<INF>su</INF>,<INF>0</INF>, T<INF>su,f</INF>, [tau]<INF>stby,1</INF>,
T<INF>t,stby</INF>,<INF>1</INF>, and T<INF>a,stby,1</INF>) reference
only one of the possible time periods. Therefore, DOE proposes to
remove references to specific time periods to reduce the possibility of
confusion and to align with the April 2021 ASHRAE Draft 118.2.
3. Test Conditions
a. Supply Water Temperature
Section 2.3 of appendix E specifies maintaining the supply water
temperature at 58 [deg]F <plus-minus>2 [deg]F (14.4 [deg]C <plus-
minus>1.1 [deg]C). During the 24-hour simulated-use test, maintaining
the supply water temperature within this range can be difficult at the
immediate start of a draw due to the short time between draw initiation
and the first measurement at 5 seconds (with subsequent measurements
every 3 seconds thereafter), as required by sections 5.4.2 and 5.4.3 of
appendix E. In some test configurations, particularly during the lower
flow rate water draws, the inlet water and piping may retain heat from
a previous draw, causing the water entering the unit during the initial
measurements to be slightly outside of tolerance. Any supply water
temperature reading outside of the test tolerances would invalidate a
test. However, due to the small percentage of total water use that
would be affected, supply water temperatures that are slightly out of
tolerance for the first one or two data points would have a negligible
effect on the overall test result.\38\ This issue is less evident
during the FHR test, which specifies an initial temperature measurement
15 seconds after the start of the water draw. This is not an issue
during the Max GPM test due to the system being in steady state during
the entire test.
---------------------------------------------------------------------------

\38\ For example, the first two temperature readings would
reflect 8 seconds of water flow, in comparison to total water draw
durations ranging from 1 minute to over 8 minutes, according to the
water draw patterns defined in Tables III.1, III.2, III.3, and III.4
of appendix E.
---------------------------------------------------------------------------

In the April 2020 RFI, DOE requested feedback on whether one or two
supply water temperature data points outside of the test tolerance at
the beginning of a draw would have a measurable effect on the results
of the test. 85 FR 21104, 21111 (April 16, 2020). DOE further requested
feedback on whether it should consider relaxing the requirement for
supply water temperature tolerances at the start of a draw, and if so,
which methods are most appropriate for doing so while maintaining
accuracy and repeatability. Id. at 85 FR 21111-21112. A.O. Smith stated
there would be no measurable effect on test results by allowing one or
two supply water temperature data points outside of the test tolerance
at the beginning of a draw. (A.O. Smith, No. 20 at p. 4) NEEA
recommended DOE conduct a sensitivity analysis to determine a
reasonable range and encouraged relaxing the requirements to ease test
burden. (NEEA, No. 21 at p. 7) A.O.

[[Page 1577]]

Smith, NEEA, and Rheem recommended that DOE allow the first one or two
measurements of the supply water temperature to be outside of test
tolerance to ease test burden. (A.O. Smith, No. 20 at p. 4; NEEA, No.
21 at p. 7; Rheem, No. 14 at p. 6) AHRI, A.O. Smith, BWC, CSA, Rheem,
and Rinnai recommended that DOE increase the time between initiating a
draw and the first data measurement from 5 seconds to 15 seconds within
section 5.4.2 of appendix E. (AHRI, No. 17 at p. 7; A.O. Smith, No. 20
at p. 4; BWC, No. 12 at p. 3; CSA, No. 10 at p. 6; Rheem, No. 14 at p.
6; Rinnai, No. 13 at p. 8) SMTI recommended that the supply water
temperature requirement be changed to: the average supply water
temperature during draws shall be 58 [deg]F <plus-minus>2 [deg]F, with
all data points being 58 [deg]F <plus-minus>5 [deg]F. (SMTI, No. 19 at
p. 4) NEEA encouraged DOE to relax the tolerances at the start of the
draw and suggested allowing a given maximum percentage deviation in
mass-weighted temperature over the course of a single draw or to set a
corresponding absolute number. (NEEA, No. 21 at p. 7) CSA recommended
that DOE adopt the March 2019 ASHRAE Draft 118.2 piping diagrams, with
the by-pass loop, to alleviate inlet temperature problems. (CSA, No. 10
at p. 6) DOE notes this supply water temperature issue has been
observed in testing with the test setup described in the March 2019
ASHRAE Draft 118.2. Therefore, adopting the March 2019 ASHRAE Draft
118.2 test setup alone would not alleviate this issue.
As explained previously, DOE agrees with commenters that one or two
supply water temperature measurements outside of tolerance at the start
of the draw will likely have no measurable effect on test results.
These outside of tolerance measurements typically occur during draws
with lower flow rates, where the inlet water line (which has been
heated slightly due to heat transferring from the water heater) is not
cleared by the first data measurement. DOE notes that during its own
testing, multiple retests were sometimes needed before a valid test was
performed. To alleviate this issue, DOE proposes to increase the time
between initiating the draw and first measurement from 5 seconds to 15
seconds in sections 5.4.2 and 5.4.3 of appendix E, as recommended by
the commenters. This proposed change may reduce test burden by reducing
the occurrence of a test being invalidated (which would require re-
testing) due to the first one or two water temperature readings
exceeding the defined temperature tolerance. Further, this proposed
change would eliminate the need to amend the supply water temperature
tolerances, which, outside of the time period at the start of a draw,
are relatively easy to maintain.
b. Test Tolerances
Section 2.2 of appendix E specifies maintaining the ambient air
temperature between 65.0 [deg]F and 70.0 [deg]F (18.3 [deg]C and 21.1
[deg]C) on a continuous basis for all types of consumer water heaters
(and residential-duty commercial water heaters) other than heat pump
water heaters. For heat pump water heaters, the dry bulb (ambient air)
temperature must be maintained between 67.5 [deg]F <plus-minus>1 [deg]F
(19.7 [deg]C <plus-minus>0.6 [deg]C), and the relative humidity must be
maintained at 50% <plus-minus>2% throughout the test. Appendix E does
not specify a relative humidity tolerance for non-heat pump water
heaters. For all water heaters, section 2.7.1 of appendix E specifies
maintaining the electrical supply voltage within <plus-minus>1% of the
center of the voltage range specified by the manufacturer. Similar to
the supply water temperature discussed previously, a brief measurement
of air temperature, relative humidity, or electrical supply voltage
that is only minimally outside of the test tolerance would invalidate a
test, but likely would have a negligible effect on the results of the
test, as the total time out of tolerance would be insignificant
compared to the total time of the test. In the April 2020 RFI, DOE
requested feedback on whether the tolerances for ambient air
temperature, relative humidity, and electrical supply voltage are
difficult to maintain at the start of a draw, and if so, whether DOE
should consider relaxing these requirements at the start of a draw and
to what extent. 85 FR 21104, 21112 (April 16, 2020).
AHRI recommended that the tolerances for the electric supply
voltage be made less stringent and noted that the current electric
supply voltage requirements require specialized equipment that is very
costly and has little effect on the UEF results. (AHRI, No. 17 at p. 8)
CSA, NEEA, Rheem, and Rinnai proposed increasing the electrical supply
voltage tolerance to <plus-minus>2 percent of the rated voltage, while
BWC proposed a tolerance of <plus-minus>5% of the rated voltage. (CSA,
No. 10 at p. 6; NEEA, No. 21 at p. 3; Rheem, No. 14 at p. 6; Rinnai,
No. 13 at p. 8; BWC, No. 12 at p. 4) CSA further stated that the
electric supply voltage tolerance should apply only when the main heat
source is on, as there are spikes in voltage when heating is turned on/
off. (CSA, No. 10 at p. 6) Keltech stated that it might be difficult to
maintain <plus-minus>1 percent voltage tolerance, as there might be
considerable voltage sag \39\ for really high amperage units, and that
the test procedure should be clearer about what is acceptable for a
power supply source to recover. (Keltech, No. 7 at p. 1)
---------------------------------------------------------------------------

\39\ A voltage sag (or swell) is a short duration change in
voltage which can be caused by sudden load changes or excessive
loads (e.g., a water heater starting or ending a recovery).
---------------------------------------------------------------------------

DOE agrees with commenters that maintaining the electric supply
voltage within <plus-minus>1 percent of the rated voltage is difficult
and requires expensive equipment, and that maintaining this narrow
tolerance range is likely not necessary to achieve repeatable and
reproducible test results. DOE further agrees with CSA and Keltech that
short spikes in the measured voltage that occur around the start and
end of a recovery, when heating components are turning on or off, have
little to no effect on UEF, but can invalidate a test. Therefore, to
reduce the potential need to re-run tests and thereby potentially
reduce test burden, DOE proposes to increase the electrical supply
voltage tolerance from <plus-minus>1 percent on a continuous basis to
<plus-minus>2 percent on a continuous basis and to add clarification
that this tolerance is only applicable beginning 5 seconds after the
start of a recovery to 5 seconds before the end of a recovery (i.e.,
only when the water heaters is undergoing a recovery). These proposed
changes may reduce test burden by reducing the need to re-run tests
while maintaining the representativeness of the test procedure.
SMTI stated that for heat pump water heaters the average dry bulb
temperature during recoveries should be 67.5 [deg]F <plus-minus>1
[deg]F, with all data points being 67.5 [deg]F <plus-minus>5 [deg]F,
and that the average dry bulb temperature during standby period should
be 67.5 [deg]F <plus-minus>2.5 [deg]F, with all data points being 67.5
[deg]F <plus-minus>5 [deg]F. (SMTI, No. 19 at p. 4) Rheem recommended a
dry bulb temperature tolerance between 65.0 [deg]F and 70.0 [deg]F for
heat pump water heaters. (Rheem, No. 14 at p. 6) Rinnai stated that the
average ambient air temperature for non-heat pump water heaters should
be 67.5 [deg]F <plus-minus>2.5 [deg]F, and that a single data point
outside of the range should not invalidate a test. (Rinnai, No. 13 at
p. 8) A.O. Smith stated that relaxing ambient air tolerance for the
first 15 minutes during the test will not have a measurable effect on
the overall test results and that DOE should investigate whether
relaxing this tolerance for the entirety of the test still provides
results that are repeatable and representative of an average use cycle.
(A.O. Smith, No. 20 at p. 4)

[[Page 1578]]

Through a review of its available test data, DOE has found that
short fluctuations in ambient temperature have little to no effect on
the test results of non-heat pump water heaters. Therefore, in an
effort to reduce the need to re-run tests in instances in which the
results of the invalid test and the valid test would not differ
significantly, and therefore reduce test burden, DOE proposes to change
the ambient temperature requirement for non-heat pump water heaters to
an average of 67.5 [deg]F <plus-minus>2.5 [deg]F, with a maximum
deviation of 67.5 [deg]F <plus-minus>5 [deg]F, as opposed to only a
maximum deviation of 67.5 [deg]F <plus-minus>2.5 [deg]F as currently
specified in the test procedure.
For heat pump water heaters, DOE agrees with SMTI that the dry bulb
temperature tolerances are important to maintain during recoveries but
are less important during standby periods when the air is not being
used to heat water. Further, through its own testing, DOE has observed
that short deviations outside of the dry bulb temperature tolerances
have little to no effect on the test results. Therefore, in an effort
to reduce the need to re-run tests in instances in which the results of
the invalid test and the valid test would not differ significantly, DOE
proposes to change the dry bulb temperature requirement for heat pump
water heaters to an average of 67.5 [deg]F <plus-minus>1 [deg]F during
recoveries and an average of 67.5 [deg]F <plus-minus>2.5 [deg]F when
not recovering, with a maximum deviation of 67.5 [deg]F <plus-minus>5
[deg]F, as opposed to only a maximum deviation of 67.5 [deg]F <plus-
minus>1 [deg]F as currently specified in the test procedure. This
proposed change would maintain the stringency of the dry bulb
temperature requirement while allowing for short deviations from the
targeted dry bulb temperature range, which would reduce the need to re-
run tests in instances in which the results of the invalid test and the
valid test would not differ significantly, and therefore reduce test
burden.
In response to the April 2020 RFI, SMTI stated that for heat pump
water heaters, the relative humidity tolerance is only relevant during
recoveries and suggested changing the relative humidity requirements to
an average of 50% <plus-minus>2%, with a maximum deviation of 50%
<plus-minus>10%. (SMTI, No. 19 at p. 4) A.O. Smith stated that relaxing
relative humidity tolerance for the first 15 minutes during the test
will not have a measurable effect on the overall test results and that
DOE should investigate whether relaxing this tolerance for the entirety
of the test still provides results that are repeatable and
representative of an average use cycle. (A.O. Smith, No. 20 at p. 4)
BWC and Rinnai supported relaxing the relative humidity tolerance, and
NEEA stated that the relative humidity tolerance should be increased
from <plus-minus>2 percent to <plus-minus>5 percent. (BWC, No. 12 at p.
4; Rinnai, No. 13 at p. 8; NEEA, No. 21 at p. 4)
For heat pump water heaters, DOE is proposing to increase the
absolute relative humidity tolerance from <plus-minus>2 percent to
<plus-minus>5 percent across the entire test, with the average relative
humidity between 50% <plus-minus>2% during recoveries. This change
would reduce test burden by reducing the need to re-run tests in
instances in which the results of the invalid test and the valid test
would not differ significantly.
As noted, appendix E does not currently specify a relative humidity
tolerance for non-heat pump water heaters. As described in the April
2020 RFI, DOE has conducted exploratory testing to investigate the
effect of relative humidity on the measured UEF values of two consumer
gas-fired instantaneous water heaters that are flow activated and have
less than 2 gallons of storage volume. 85 FR 21104, 21112 (April 16,
2020). Of the two models tested, one used non-condensing technology and
the other used condensing technology. For each model, two tests were
performed at a relative humidity of 50 percent, and two tests were
performed at a relative humidity of 80 percent (i.e., a total of four
tests for each model). Id. Increasing in relative humidity from 50
percent to 80 percent resulted in a maximum change in UEF for the non-
condensing and condensing models of 0.011 and 0.015, respectively. Id.
Given that DOE requires reporting UEF to the nearest 0.01 (see 10 CFR
429.17(b)(2)), a change in UEF on the order of 0.01-0.02 as suggested
by DOE's test results could be considered as substantively impacting
the test results. DOE is still examining this issue and requests
comment and test data on whether a relative humidity requirement should
be added to appendix E for non-heat pump water heaters.

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