Energy Conservation Program: Energy Conservation Standards for Consumer Boilers

Federal RegisterAug 14, 2023

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DEPARTMENT OF ENERGY

10 CFR Part 430

[EERE-2019-BT-STD-0036]

RIN 1904-AE82

Energy Conservation Program: Energy Conservation Standards for Consumer Boilers

AGENCY:

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

ACTION:

Notice of proposed rulemaking and announcement of public meeting.

SUMMARY:

The Energy Policy and Conservation Act, as amended (EPCA), prescribes energy conservation standards for various consumer products and certain commercial and industrial equipment, including consumer boilers. EPCA also requires the U.S. Department of Energy (DOE or the Department) to periodically determine whether more-stringent standards would be technologically feasible and economically justified and would result in significant energy savings. In this notice of proposed rulemaking (NOPR), DOE proposes amended energy conservation standards for consumer boilers, and also announces a public meeting to receive comment on these proposed standards and associated analyses and results.

DATES:

Comments:

DOE will accept comments, data, and information regarding this NOPR no later than October 13, 2023.

Meeting:

DOE will hold a public meeting via webinar on Tuesday, September 12, 2023 from 1:00 p.m. to 4:00 p.m. See section VII, “Public Participation,” for webinar registration information, participant instructions and information about the capabilities available to webinar participants.

Comments regarding the likely competitive impact of the proposed standard should be sent to the Department of Justice contact listed in the

ADDRESSES

section on or before September 13, 2023.

ADDRESSES:

Interested persons are encouraged to submit comments using the Federal eRulemaking Portal at

www.regulations.gov

under docket number EERE-2019-BT-STD-0036. Follow the instructions for submitting comments. Alternatively, interested persons may submit comments, identified by docket number EERE-2019-BT-STD-0036 and/or RIN 1904-AE82, by any of the following methods:

Email: ConsumerBoilers2019STD0036@ee.doe.gov.

Include the docket number EERE-2019-BT-STD-0036 and/or RIN 1904-AE82 in the subject line of the message.

Postal Mail:

Appliance and Equipment Standards Program, U.S. Department of Energy, Building Technologies Office, Mailstop EE-5B, 1000 Independence Avenue SW, Washington, DC 20585-0121. If possible, please submit all items on a compact disc (CD), in which case it is not necessary to include printed copies.

Hand Delivery/Courier:

Appliance and Equipment Standards Program, U.S. Department of Energy, Building Technologies Office, 950 L'Enfant Plaza SW, 6th Floor, Washington, DC 20024. Telephone: (202) 287-1445. If possible, please submit all items on a CD, in which case it is not necessary to include printed copies.

No telefacsimiles (faxes) will be accepted. For detailed instructions on submitting comments and additional information on this process, see section VII (Public Participation) of this document.

Docket:

The docket for this activity, which includes

Federal Register

notices, comments, and other supporting documents/materials, is available for review at

www.regulations.gov.

All documents in the docket are listed in the

www.regulations.gov

index. However, not all documents listed in the index may be publicly available, such as information that is exempt from public disclosure.

The docket web page can be found at

www.regulations.gov/docket/EERE-2019-BT-STD-0036.

The docket web page contains instructions on how to access all documents, including public comments, in the docket. See section VII (Public Participation) of this document for information on how to submit comments through

www.regulations.gov.

EPCA requires the Attorney General to provide DOE a written determination of whether the proposed standard is likely to lessen competition. The U.S. Department of Justice Antitrust Division invites input from market participants and other interested persons with views on the likely competitive impact of the proposed standard for consumer boilers. Interested persons may contact the Division at

energy.standards@usdoj.gov

on or before the date specified in the

DATES

section. Please indicate in the “Subject” line of your email the title and Docket Number of this proposed rulemaking.

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: (240) 597-6737. Email:

ApplianceStandardsQuestions@ee.doe.gov.

Mr. Eric Stas, U.S. Department of Energy, Office of the General Counsel, GC-33, 1000 Independence Avenue SW, Washington, DC 20585-0121. Telephone: (202) 586-5827. Email:

Eric.Stas@hq.doe.gov.

For further information on how to submit a comment, review other public comments and the docket, or participate in the public meeting webinar, contact the Appliance and Equipment Standards Program staff at (202) 287-1445 or by email:

ApplianceStandardsQuestions@ee.doe.gov.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Synopsis of the Proposed Rule

A. Benefits and Costs to Consumers

B. Impact on Manufacturers

C. National Benefits and Costs

D. Conclusion

II. Introduction

A. Authority

B. Background

1. Current Standards

2. History of Standards Rulemaking for Consumer Boilers

C. Deviation From Appendix A

III. General Discussion

A. General Comments

B. Scope of Coverage

C. Test Procedure

D. Boilers Not Requiring Electricity

E. Technological Feasibility

1. General

2. Maximum Technologically Feasible Levels

F. Energy Savings

1. Determination of Savings

2. Significance of Savings

G. Economic Justification

1. Specific Criteria

a. Economic Impact on Manufacturers and Consumers

b. Savings in Operating Costs Compared To Increase in Price (LCC and PBP)

c. Energy Savings

d. Lessening of Utility or Performance of Products

e. Impact of Any Lessening of Competition

f. Need for National Energy Conservation

g. Other Factors

2. Rebuttable Presumption

IV. Methodology and Discussion of Related Comments

A. Market and Technology Assessment

1. Product Classes

a. Fossil Fuel-Fired Hot Water Boilers

b. Hydronic Heat Pump Boilers

2. Market Assessment

3. Technology Options

B. Screening Analysis

1. Screened-Out Technologies

2. Remaining Technologies

C. Engineering Analysis

1. Efficiency Analysis

a. Baseline Efficiency

b. Higher Efficiency Levels

2. Cost Analysis

3. Manufacturer Markup and Shipping Costs

4. Cost-Efficiency Results

D. Markups Analysis

E. Energy Use Analysis

1. Building Sample

2. Space Heating Energy Use

a. Heating Load Calculation

b. Impact of Return Water Temperature on Efficiency

c. Impact of Jacket Losses on Energy Use

d. Impact of Excess Air Adjustments

3. Water Heating Use

F. Life-Cycle Cost and Payback Period Analysis

1. Product Cost

2. Installation Cost

3. Annual Energy Consumption

4. Energy Prices

5. Maintenance and Repair Costs

6. Product Lifetime

7. Discount Rates

8. Energy Efficiency Distribution in the No-New-Standards Case

9. Payback Period Analysis

G. Shipments Analysis

H. National Impact Analysis

1. Product Efficiency Trends

2. National Energy Savings

3. Net Present Value Analysis

I. Consumer Subgroup Analysis

J. Manufacturer Impact Analysis

1. Overview

2. Government Regulatory Impact Model and Key Inputs

a. Manufacturer Production Costs

b. Shipments Projections

c. Product and Capital Conversion Costs

d. Manufacturer Markup Scenarios

3. Manufacturer Interviews

a. The Replacement Market

4. Discussion of MIA Comments

K. Emissions Analysis

1. Air Quality Regulations Incorporated in DOE's Analysis

L. Monetizing Emissions Impacts

1. Monetization of Greenhouse Gas Emissions

a. Social Cost of Carbon

b. Social Cost of Methane and Nitrous Oxide

2. Monetization of Other Emissions Impacts

M. Utility Impact Analysis

N. Employment Impact Analysis

V. Analytical Results and Conclusions

A. Trial Standard Levels

B. Economic Justification and Energy Savings

1. Economic Impacts on Individual Consumers

a. Life-Cycle Cost and Payback Period

b. Consumer Subgroup Analysis

c. Rebuttable Presumption Payback

2. Economic Impacts on Manufacturers

a. Industry Cash-Flow Analysis Results

b. Direct Impacts on Employment

c. Impacts on Manufacturing Capacity

d. Impacts on Subgroups of Manufacturers

e. Cumulative Regulatory Burden

3. National Impact Analysis

a. Significance of Energy Savings

b. Net Present Value of Consumer Costs and Benefits

c. Indirect Impacts on Employment

4. Impact on Utility or Performance of Products

5. Impact of Any Lessening of Competition

6. Need of the Nation To Conserve Energy

7. Other Factors

8. Summary of Economic Impacts

C. Conclusion

1. Benefits and Burdens of TSLs Considered for Consumer Boiler Standards

2. Annualized Benefits and Costs of the Proposed Standards

D. Reporting, Certification, and Sampling Plan

VI. Procedural Issues and Regulatory Review

A. Review Under Executive Orders 12866 and 13563

B. Review Under the Regulatory Flexibility Act

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 the Treasury and General Government Appropriations Act, 2001

K. Review Under Executive Order 13211

L. Review Under the Information Quality Bulletin for Peer Review

VII. Public Participation

A. Participation in the Public Meeting Webinar

B. Procedure for Submitting Prepared General Statements for Distribution

C. Conduct of the Webinar

D. Submission of Comments

E. Issues on Which DOE Seeks Comment

VIII. Approval of the Office of the Secretary

I. Synopsis of the Proposed Rule

The Energy Policy and Conservation Act, as amended (EPCA),

Public Law 94-163 (codified at 42 U.S.C. 6291-6317), authorizes DOE to regulate the energy efficiency of a number of consumer products and certain industrial equipment. (42 U.S.C. 6291-6317) Title III, Part B

of EPCA established the Energy Conservation Program for Consumer Products Other Than Automobiles. (42 U.S.C. 6291-6309) These products include consumer boilers, the subject of this rulemaking. (42 U.S.C. 6292(a)(5))

All references to EPCA in this document refer to the statute as amended through the Energy Act of 2020, Public Law 116-260 (Dec. 27, 2020), which reflect the last statutory amendments that impact Parts A and A-1 of EPCA.

For editorial reasons, upon codification in the U.S. Code, Part B was redesignated Part A.

DOE notes that consumer boilers are defined as a subcategory of covered consumer furnaces (

see

42 U.S.C. 6291(23)).

Pursuant to EPCA, any new or amended energy conservation standard must be designed to achieve the maximum improvement in energy efficiency that DOE determines is technologically feasible and economically justified. (42 U.S.C. 6295(o)(2)(A)) Furthermore, the new or amended standard must result in a significant conservation of energy. (42 U.S.C. 6295(o)(3)(B)) EPCA also provides that not later than six years after issuance of any final rule establishing or amending a standard, DOE must publish either a notice of determination that standards for the product do not need to be amended, or a notice of proposed rulemaking including new proposed energy conservation standards (proceeding to a final rule, as appropriate). (42 U.S.C. 6295(m)(1))

In accordance with these and other statutory provisions discussed in this document, DOE analyzed the benefits and burdens of four trial standard levels (TSLs) for consumer boilers. The TSLs and their associated benefits and burdens are discussed in detail in sections V.A-C of this document. As discussed in section V.C of this document, DOE has tentatively determined that TSL 3 represents the maximum improvement in energy efficiency that is technologically feasible and economically justified. The proposed standards at TSL 3, which are expressed in minimum annual fuel utilization efficiency (AFUE), standby mode power consumption (P

W,SB

) and off mode power consumption (P

W,OFF

), are shown in Table I.1. These proposed standards, if adopted, would apply to all consumer boilers listed in Table I.1 manufactured in, or imported into, the United States starting on the date five years after the date of publication of the final rule for this rulemaking. Specifically, DOE is proposing more-stringent AFUE standards for gas-fired and oil-fired boilers while maintaining the current standards for electric steam and hot water boilers. Additionally, DOE is proposing to maintain the design requirements and exceptions to the minimum AFUE requirements established by statute and currently codified at 10 CFR 430.32(e)(2). (

See

42 U.S.C. 6295(f)(3)(A)-(C))

Table I.1—Proposed Energy Conservation Standards for Consumer Boilers

Product class

AFUE

(%) *

W,SB

(W) *

W,OFF

(W) *

Design requirements *

Gas-fired Hot Water

Constant-burning pilot not permitted. Automatic means for adjusting water temperature required (except for boilers equipped with tankless domestic water heating coils).

Gas-Fired Steam

Constant-burning pilot not permitted.

Oil-fired Hot Water

Automatic means for adjusting temperature required (except for boilers equipped with tankless domestic water heating coils).

Oil-fired Steam

None.

Electric Hot Water

None

Automatic means for adjusting temperature required (except for boilers equipped with tankless domestic water heating coils).

Electric Steam

None

None.

W,SB

, P

W,OFF

, or design requirements, but must meet the requirements of 10 CFR 430.32(e)(2)(i) which include a minimum AFUE of 75 percent for gas-fired steam boilers and a minimum AFUE of 80 percent for all other boilers.

A. Benefits and Costs to Consumers

Table I.2 presents DOE's evaluation of the economic impacts of the proposed standards on consumers of consumer boilers, as measured by the average life-cycle cost (LCC) savings and the simple payback period (PBP).

The average LCC savings are positive for all product classes, and the PBP is less than the average lifetime of consumer boilers, which is estimated to be 26.9 years for gas-fired hot water boilers, 23.7 years for gas-fired steam boilers, 25.6 years for oil-fired hot water boilers, and 19.6 years for oil-fired steam boilers (see section IV.F.6 of this document for further details).

The average LCC savings refer to consumers that are affected by a standard and are measured relative to the distribution of purchased boilers, and their associated energy efficiency, in the no-new-standards case, which depicts the market in the compliance year in the absence of new or amended standards (see section IV.F.8 of this document). The simple PBP, which is designed to compare specific efficiency levels, is measured relative to the baseline product (see section IV.C of this document).

Table I.2—Impacts of Proposed Energy Conservation Standards on Consumers of Consumer Boilers

Product class

Average LCC

savings

(2022$)

Simple payback period

(years)

Gas-fired Hot Water

768

2.7

Gas-fired Steam

Oil-fired Hot Water

666

3.3

Oil-fired Steam

310

5.5

DOE's analysis of the impacts of the proposed standards on consumers is described in section IV.F of this document.

B. Impact on Manufacturers

All monetary values in this document are expressed in 2022 dollars.

The industry net present value (INPV) is the sum of the discounted cash flows starting from the publication year (2023) of the NOPR and continuing through the 30-year period following the expected compliance date of the standards (2023-2059). Using a real discount rate of 9.7 percent, DOE estimates that the INPV for manufacturers of consumer boilers in the case without amended standards is $532.0 million. Under the proposed standards, the change in INPV is estimated to range from −11.7 percent to −7.7 percent, which is approximately −$62.2 million to −$40.7 million. In order to bring products into compliance with amended standards, it is estimated that the industry would incur total conversion costs of $98.0 million.

DOE's analysis of the impacts of the proposed standards on manufacturers is described in section IV.J of this document. The analytic results of the manufacturer impact analysis (MIA) are presented in section V.B.2 of this document.

C. National Benefits and Costs

DOE's analyses indicate that the proposed energy conservation standards for consumer boilers would save a significant amount of energy. Relative to the case without amended standards, the lifetime energy savings for consumer boilers purchased in the 30-year period that begins in the anticipated year of compliance with the amended standards (2030-2059) amount to 0.7 quadrillion British thermal units (Btu), or quads.

This represents a savings of 2.3 percent relative to the energy use of these products in the case without amended standards (referred to as the “no-new-standards case” or as the baseline).

The quantity refers to full-fuel-cycle (FFC) energy savings. FFC energy savings includes the energy consumed in extracting, processing, and transporting primary fuels (

i.e.,

coal, natural gas, petroleum fuels), and, thus, presents a more complete picture of the impacts of energy efficiency standards. For more information on the FFC metric, see section IV.H.1 of this document.

The cumulative net present value (NPV) of total consumer benefits of the proposed standards for consumer boilers ranges from $0.72 billion (at a 7-percent discount rate) to $2.27 billion (at a 3-percent discount rate). This NPV expresses the estimated total value of future operating-cost savings minus the estimated increased product and installation costs for consumer boilers purchased in 2030-2059 relative to the baseline.

In addition, the proposed standards for consumer boilers are projected to yield significant environmental benefits. DOE estimates that the proposed standards would result in cumulative emission reductions (over the same period as for energy savings) of 39 million metric tons (Mt)

of carbon dioxide (CO

), 438 thousand tons of

methane (CH

), 0.17 thousand tons of nitrous oxide (N

O), 105 thousand tons of nitrogen oxides (NO

), and 2.7 thousand tons of sulfur dioxide (SO

), and an increase of 0.001 tons of mercury (Hg) due to slightly higher electricity consumption.

A metric ton is equivalent to 1.1 short tons. Results for emissions other than CO

are presented in short tons.

DOE calculated emissions reductions relative to the no-new-standards case, which reflects key assumptions in the

Annual Energy Outlook 2023

(

AEO 2023

represents current Federal and State legislation and final implementation of regulations as of the time of its preparation. See section IV.K of this document for further discussion of

AEO2023

assumptions that effect air pollutant emissions.

DOE estimates the value of climate benefits from a reduction in greenhouse gases (GHG) using four different estimates of the social cost of CO

(SC-CO

), the social cost of methane (SC-CH

), and the social cost of nitrous oxide (SC-N

O). Together these represent the social cost of GHG (SC-GHG). DOE used interim SC-GHG values developed by an Interagency Working Group on the Social Cost of Greenhouse Gases (IWG).

The derivation of these values is discussed in section IV.L of this document. For presentational purposes, the climate benefits associated with the average SC-GHG at a 3-percent discount rate over the period of analysis are estimated to be $2.0 billion. DOE does not have a single central SC-GHG point estimate, and it emphasizes the importance and value of considering the benefits calculated using all four sets of SC-GHG estimates.

To monetize the benefits of reducing GHG emissions this analysis uses the interim estimates presented in the

Technical Support Document: Social Cost of Carbon, Methane, and Nitrous Oxide Interim Estimates Under Executive Order 13990

published in February 2021 by the IWG. (“February 2021 SC-GHG TSD”).

www.whitehouse.gov/wp-content/uploads/2021/02/TechnicalSupportDocument_SocialCostofCarbonMethaneNitrousOxide.pdf.

DOE estimated the monetary health benefits of SO

and NO

emissions reductions using benefit per ton estimates from the scientific literature, as discussed in section IV.L of this document. DOE estimated the present value of the health benefits would be $1.1 billion using a 7-percent discount rate, and $3.3 billion using a 3-percent discount rate.

DOE is currently only monetizing (for SO

and NO

) health benefits from changes in fine particulate matter (PM

2.5

) precursors (SO

and NO

) and for changes in an ozone precursor (NO

), but will continue to assess the ability to monetize other effects such as health benefits from reductions in direct PM

2.5

emissions.

DOE estimates the economic value of these emissions reductions resulting from the considered trial standard levels (TSLs) for the purpose of complying with the requirements of Executive Order 12866.

Table I.3 summarizes the monetized benefits and costs expected to result from the proposed standards for consumer boilers. There are other important unquantified effects, including certain unquantified climate benefits, unquantified public health benefits from the reduction of toxic air pollutants and other emissions, unquantified energy security benefits, and distributional effects, among others.

Table I.3—Present Value of Monetized Benefits and Costs of Proposed Energy Conservation Standards for Consumer Boilers

[TSL 3]

Billion 2022$

3% discount rate

Consumer Operating Cost Savings

3.1

Climate Benefits *

2.0

Health Benefits **

3.3

Total Monetized Benefits †

8.5

Consumer Incremental Product Costs ‡

0.8

Net Monetized Benefits

7.6

Change in Producer Cashflow (INPV

‡‡

)

(0.06)−(0.04)

7% discount rate

Consumer Operating Cost Savings

1.1

Climate Benefits * (3% discount rate)

2.0

Health Benefits **

1.1

Total Monetized Benefits †

4.3

Consumer Incremental Product Costs ‡

0.4

Net Monetized Benefits

3.9

Change in Producer Cashflow (INPV

‡‡

)

(0.06)−(0.04)

Note:

This table presents present value (in 2022$) of the costs and benefits associated with consumer boilers shipped in 2030-2059. These results include benefits which accrue after 2059 from the products shipped in 2030-2059.

* Climate benefits are calculated using four different estimates of the social cost of carbon (SC-CO

), methane (SC-CH

), and nitrous oxide (SC-N

O) (model average at 2.5-percent, 3-percent, and 5-percent discount rates; 95th percentile at 3-percent discount rate) (see section IV.L of this document). Together these represent the global SC-GHG. For presentational purposes of this table, the climate benefits associated with the average SC-GHG at a 3-percent discount rate are shown; however, DOE emphasizes the importance and value of considering the benefits calculated using all four sets of SC-GHG estimates. To monetize the benefits of reducing GHG emissions, this analysis uses the interim estimates presented in the

Technical Support Document: Social Cost of Carbon, Methane, and Nitrous Oxide Interim Estimates Under Executive Order 13990

published in February 2021 by the IWG.

** Health benefits are calculated using benefit-per-ton values for NO

and SO

. DOE is currently only monetizing (for SO

and NO

) PM

2.5

precursor health benefits and (for NO

) ozone precursor health benefits, but will continue to assess the ability to monetize other effects such as health benefits from reductions in direct PM

2.5

emissions.

See

section IV.L of this document for more details.

† Total and net benefits include those consumer, climate, and health benefits that can be quantified and monetized. For presentation purposes, total and net benefits for both the 3-percent and 7-percent cases are presented using the average SC-GHG with 3-percent discount rate, but DOE does not have a single central SC-GHG point estimate. DOE emphasizes the importance and value of considering the benefits calculated using all four sets of SC-GHG estimates.

‡ Costs include incremental equipment costs as well as installation costs.

‡‡ Operating Cost Savings are calculated based on the life cycle costs analysis and national impact analysis as discussed in detail below. See sections IV.F and IV.H of this document. DOE's NIA includes all impacts (both costs and benefits) along the distribution chain beginning with the increased costs to the manufacturer to manufacture the product and ending with the increase in price experienced by the consumer. DOE also separately conducts a detailed analysis on the impacts on manufacturers (the MIA). See section IV.J of this document. In the detailed MIA, DOE models manufacturers' pricing decisions based on assumptions regarding investments, conversion costs, cashflow, and margins. The MIA produces a range of impacts, which is the rule's expected impact on the INPV. The change in INPV is the present value of all changes in industry cash flow, including changes in production costs, capital expenditures, and manufacturer profit margins. Change in INPV is calculated using the industry weighted average cost of capital value of 9.7 percent that is estimated in the manufacturer impact analysis (see chapter 12 of the NOPR TSD for a complete description of the industry weighted average cost of capital). For consumer boilers, those values are −$62 million and −$41 million. DOE accounts for that range of likely impacts in analyzing whether a TSL is economically justified. See section V.C of this document. DOE is presenting the range of impacts to the INPV under two markup scenarios: the Preservation of Gross Margin scenario, which is the manufacturer markup scenario used in the calculation of Consumer Operating Cost Savings in this table, and the Preservation of Operating Profit Markup scenario, where DOE assumed manufacturers would not be able to increase per-unit operating profit in proportion to increases in manufacturer production costs. DOE includes the range of estimated INPV in the above table, drawing on the MIA explained further in section IV.J, to provide additional context for assessing the estimated impacts of this proposal to society, including potential changes in production and consumption, which is consistent with OMB's Circular A-4 and E.O. 12866. If DOE were to include the INPV into the net benefit calculation for this proposed rule, the net benefits would range from $7.54 billion to $7.56 billion at 3-percent discount rate and would range from $3.84 billion to $3.86 billion at 7-percent discount rate. DOE seeks comment on this approach.

The benefits and costs of the proposed standards can also be expressed in terms of annualized values. The monetary values for the total annualized net benefits are: (1) the reduced consumer operating costs, minus (2) the increase in product purchase prices and installation costs, plus (3) the monetized value of climate and health benefits of emission reductions, all annualized.

To convert the time-series of costs and benefits into annualized values, DOE calculated a present value in 2023, the year used for discounting the NPV of total consumer costs and savings. For the benefits, DOE calculated a present value associated with each year's shipments in the year in which the shipments occur (

e.g.,

2030), and then discounted the present value from each year to 2023. Using the present value, DOE then calculated the fixed annual payment over a 30-year period, starting in the compliance year, that yields the same present value.

The national operating cost savings are domestic private U.S. consumer monetary savings that occur as a result of purchasing the covered products and are measured for the lifetime of consumer boilers shipped in 2030-2059. The benefits associated with reduced emissions achieved as a result of the proposed standards are also calculated based on the lifetime of consumer boilers shipped in 2030-2059. Total benefits for both the 3-percent and 7-percent cases are presented using the average GHG social costs with 3-percent discount rate. Estimates of SC-GHG values are presented for all four discount rates in section IV.L.1 of this document.

Table I.4 presents the total estimated monetized benefits and costs associated with the proposed standard, expressed in terms of annualized values. The results under the primary estimate are as follows.

Using a 7-percent discount rate for consumer benefits and costs and health benefits from reduced NO

and SO

emissions, and the 3-percent discount rate case for climate benefits from reduced GHG emissions, the estimated monetized cost of the standards proposed in this rule is $52 million per year in increased equipment costs, while the estimated annual benefits are $139 million in reduced equipment operating costs, $124 million in monetized climate benefits, and $137 million in monetized health benefits. In this case, the net monetized benefit would amount to $348 million per year.

Using a 3-percent discount rate for all benefits and costs, the estimated monetized cost of the proposed standards is $50 million per year in increased equipment costs, while the estimated annual monetized benefits are $188 million in reduced operating costs, $124 million in monetized climate benefits, and $204 million in in monetized air pollutant health benefits. In this case, the net benefit would amount to $466 million per year.

Table I.4—Annualized Monetized Benefits and Costs of Proposed Energy Conservation Standards for Consumer Boilers

[TSL 3]

Million 2022$/year

Primary

estimate

Low-net-

benefits

estimate

High-net-

benefits

estimate

3% discount rate

Consumer Operating Cost Savings

188

175

233

Climate Benefits *

124

121

144

Health Benefits **

204

200

237

Total Monetized Benefits †

516

496

613

Consumer Incremental Product Costs ‡

Net Monetized Benefits

466

438

575

Change in Producer Cashflow (INPV

‡‡

)

(6)−(4)

7% discount rate

Consumer Operating Cost Savings

139

129

169

Climate Benefits * (3% discount rate)

124

121

144

Health Benefits **

137

135

158

Total Monetized Benefits †

400

385

470

Consumer Incremental Product Costs ‡

Net Monetized Benefits

348

326

430

Change in Producer Cashflow (INPV

‡‡

)

(6)−(4)

Note:

This table presents the present value (in 2022$) of the costs and benefits associated with consumer boilers shipped in 2030-2059. These results include benefits which accrue after 2059 from the products shipped in 2030-2059. The Primary, Low-Net-Benefits, and High-Net-Benefits Estimates utilize projections of energy prices from the

AEO 2023

Reference case, Low-Economic-Growth case, and High-Economic-Growth case, respectively. In addition, incremental equipment costs reflect a constant trend in the Primary Estimate, an increasing rate in the Low-Net-Benefits Estimate, and a decreasing rate in the High-Net-Benefits Estimate. The methods used to derive projected price trends are explained in sections IV.F.1 and IV.H.3 of this document. Note that the Benefits and Costs may not sum to the Net Benefits due to rounding.

* Climate benefits are calculated using four different estimates of the global SC-GHG (see section IV.L of this document). For presentational purposes of this table, the climate benefits associated with the average SC-GHG at a 3-percent discount rate are shown; however, DOE emphasizes the importance and value of considering the benefits calculated using all four sets of SC-GHG estimates. To monetize the benefits of reducing GHG emissions, this analysis uses the interim estimates presented in the

Technical Support Document: Social Cost of Carbon, Methane, and Nitrous Oxide Interim Estimates Under Executive Order 13990

published in February 2021 by the IWG.

** Health benefits are calculated using benefit-per-ton values for NO

and SO

. DOE is currently only monetizing (for SO

and NO

) PM

2.5

precursor health benefits and (for NO

) ozone precursor health benefits, but will continue to assess the ability to monetize other effects such as health benefits from reductions in direct PM

2.5

emissions. See section IV.L of this document for more details.

† Total benefits for both the 3-percent and 7-percent cases are presented using the average SC-GHG with 3-percent discount rate, but the Department does not have a single central SC-GHG point estimate.

‡ Costs include incremental equipment costs as well as installation costs.

‡‡ Operating Cost Savings are calculated based on the life cycle costs analysis and national impact analysis as discussed in detail below. See sections IV.F and IV.H of this document. DOE's NIA includes all impacts (both costs and benefits) along the distribution chain beginning with the increased costs to the manufacturer to manufacture the product and ending with the increase in price experienced by the consumer. DOE also separately conducts a detailed analysis on the impacts on manufacturers (the MIA). See section IV.J of this document. In the detailed MIA, DOE models manufacturers' pricing decisions based on assumptions regarding investments, conversion costs, cashflow, and margins. The MIA produces a range of impacts, which is the rule's expected impact on the INPV. The change in INPV is the present value of all changes in industry cash flow, including changes in production costs, capital expenditures, and manufacturer profit margins. The annualized change in INPV is calculated using the industry weighted average cost of capital value of 9.7 percent that is estimated in the manufacturer impact analysis (see chapter 12 of the NOPR TSD for a complete description of the industry weighted average cost of capital). For consumer boilers, those values are −$6 million and −$4 million. DOE accounts for that range of likely impacts in analyzing whether a TSL is economically justified. See section V.C of this document. DOE is presenting the range of impacts to the INPV under two markup scenarios: the Preservation of Gross Margin scenario, which is the manufacturer markup scenario used in the calculation of Consumer Operating Cost Savings in this table, and the Preservation of Operating Profit Markup scenario, where DOE assumed manufacturers would not be able to increase per-unit operating profit in proportion to increases in manufacturer production costs. DOE includes the range of estimated annualized change in INPV in the above table, drawing on the MIA explained further in section IV.J of this document, to provide additional context for assessing the estimated impacts of this proposal to society, including potential changes in production and consumption, which is consistent with OMB's Circular A-4 and E.O. 12866. If DOE were to include the INPV into the annualized net benefit calculation for this proposed rule, the annualized net benefits would range from $460 million to $462 million at 3-percent discount rate and would range from $342 million to $344 million at 7-percent discount rate. DOE seeks comment on this approach.

DOE's analysis of the national impacts of the proposed standards is described in sections IV.H, IV.K and IV.L of this document.

D. Conclusion

DOE has tentatively concluded that the proposed standards represent the maximum improvement in energy efficiency that is technologically feasible and economically justified, and would result in the significant conservation of energy. Specifically, with regards to technological feasibility, products achieving these standard levels are already commercially available for all product classes covered by this proposal. As for economic justification, DOE's analysis shows that the benefits of the proposed standard exceed, to a great extent, the burdens of the proposed standards.

Using a 7-percent discount rate for consumer benefits and costs and NO

and SO

reduction benefits, and a 3-percent discount rate case for GHG social costs, the estimated monetized cost of the proposed standards for consumer boilers is $52 million per year from increased consumer boiler costs, while the estimated annual monetized benefits are $139 million in reduced consumer boiler operating costs, $124 million in monetized climate benefits, and $137 million in monetized air pollutant health benefits. The net monetized benefit amounts to $348 million per year.

The significance of energy savings offered by a new or amended energy conservation standard cannot be determined without knowledge of the specific circumstances surrounding a given rulemaking.

For example, some covered products and equipment have substantial energy consumption occur during periods of peak energy demand. The impacts of these products on the energy infrastructure can be more pronounced than products with relatively constant demand. Accordingly, DOE evaluates the significance of energy savings on a case-by-case basis.

Procedures, Interpretations, and Policies for Consideration in New or Revised Energy Conservation Standards and Test Procedures for Consumer Products and Commercial/Industrial Equipment, 86 FR 70892, 70901 (Dec. 13, 2021).

As previously mentioned, the proposed standards are projected to result in estimated national energy savings of 0.7 quads full-fuel-cycle (FFC), the equivalent of the primary annual energy use of 6.5 million homes, and NPV of total consumer benefits from $0.72 billion (at a 7-percent discount rate) to $2.27 billion (at a 3-percent discount rate) over the 30-year analysis period beginning with the expected compliance year (2030-2059). In addition, they are projected to reduce CO

emissions by 44 Mt. Based on these findings, DOE has initially determined the energy savings from the proposed standard levels are “significant” within the meaning of 42 U.S.C. 6295(o)(3)(B). A more detailed discussion of the basis for these tentative conclusions is contained in the remainder of this

document and the accompanying technical support document (TSD).

The TSD is available in the docket for this rulemaking at:

www.regulations.gov/docket/EERE-2019-BT-STD-0036.

DOE also considered more-stringent energy efficiency levels as potential standards, and is still considering them in this rulemaking. However, DOE has tentatively concluded that the potential burdens of the more-stringent energy efficiency levels would outweigh the projected benefits.

Based on consideration of the public comments DOE receives in response to this document and related information collected and analyzed during the course of this rulemaking effort, DOE may adopt energy efficiency levels presented in this document that are either higher or lower than the proposed standards, or some combination of level(s) that incorporate the proposed standards in part.

II. Introduction

The following section briefly discusses the statutory authority underlying this proposed rule, as well as some of the relevant historical background related to the establishment of standards for consumer boilers.

A. Authority

EPCA, Public Law 94-163 (codified at 42 U.S.C. 6291-6317) authorizes DOE to regulate the energy efficiency of a number of consumer products and certain industrial equipment. Title III, Part B of EPCA established the Energy Conservation Program for Consumer Products Other Than Automobiles. (42 U.S.C. 6291-6309) These products include consumer boilers, the subject of this document. (42 U.S.C. 6292(a)(5))

EPCA prescribed energy conservation standards for these products (42 U.S.C. 6295(f)(3)), and the statute directed DOE to conduct future rulemakings to determine whether to amend these standards. (42 U.S.C. 6295(f)(4)(C)) EPCA further provides that, not later than six years after the issuance of any final rule establishing or amending a standard, DOE must publish either a notice of determination that standards for the product do not need to be amended, or a NOPR including new proposed energy conservation standards (proceeding to a final rule, as appropriate). (42 U.S.C. 6295(m)(1))

Under EPCA, the energy conservation program consists essentially of four parts: (1) testing, (2) labeling, (3) Federal energy conservation standards, and (4) certification and enforcement procedures. Relevant provisions of EPCA specifically include definitions (42 U.S.C. 6291), test procedures (42 U.S.C. 6293), labeling provisions (42 U.S.C. 6294), energy conservation standards (42 U.S.C. 6295), and the authority to require information and reports from manufacturers (42 U.S.C. 6296).

Federal energy efficiency requirements for covered products established under EPCA generally supersede State laws and regulations concerning energy conservation testing, labeling, and standards. (42 U.S.C. 6297(a)-(c)) DOE may, however, grant waivers of Federal preemption in limited circumstances for particular State laws or regulations, in accordance with the procedures and other provisions set forth under EPCA. (

See

42 U.S.C. 6297(d))

Subject to certain criteria and conditions, DOE is required to develop test procedures to measure the energy efficiency, energy use, or estimated annual operating cost of each covered product. (42 U.S.C. 6295(o)(3)(A) and 6295(r)) Manufacturers of covered products must use the prescribed DOE test procedure as the basis for certifying to DOE that their products comply with the applicable energy conservation standards adopted under EPCA and when making representations to the public regarding the energy use or efficiency of those products. (42 U.S.C. 6293(c) and 42 U.S.C. 6295(s)) Similarly, DOE must use these test procedures to determine whether the products comply with standards adopted pursuant to EPCA. (42 U.S.C. 6295(s)) The DOE test procedures for consumer boilers appear at title 10 of the Code of Federal Regulations (CFR) part 430, subpart B, appendix EE.

On March 13, 2023, DOE published a final rule in the

Federal Register

amending the test procedure for consumer boilers and moving this test procedure to a new appendix EE effective on April 12, 2023. 88 FR 15510.

DOE must follow specific statutory criteria for prescribing new or amended standards for covered products, including consumer boilers. EPCA requires that any new or amended energy conservation standard for a covered product must be designed to achieve the maximum improvement in energy efficiency that the Secretary of Energy determines is technologically feasible and economically justified. (42 U.S.C. 6295(o)(2)(A) and (o)(3)(B)) DOE may not adopt any standard that would not result in the significant conservation of energy. (42 U.S.C. 6295(o)(3))

Moreover, DOE may not prescribe a standard: (1) for certain products, including consumer boilers, if no test procedure has been established for the product, or (2) if DOE determines by rule that the standard is not technologically feasible or economically justified. (42 U.S.C. 6295(o)(3)(A)-(B)) In deciding whether a proposed standard is economically justified, DOE must determine whether the benefits of the standard exceed its burdens. (42 U.S.C. 6295(o)(2)(B)(i)) DOE must make this determination after receiving comments on the proposed standard, and by considering, to the greatest extent practicable, the following seven statutory factors:

(1) The economic impact of the standard on manufacturer and consumers of the products subject to the standard;

(2) The savings in operating costs throughout the estimated average life of the covered products in the type (or class) compared to any increase in the price of, initial charges for, or maintenance expenses for the covered products that are likely to result from the standard;

(3) The total projected amount of energy (or as applicable, water) savings likely to result directly from the standard;

(4) Any lessening of the utility or the performance of the covered products likely to result from the standard;

(5) The impact of any lessening of competition, as determined in writing by the Attorney General, that is likely to result from the standard;

(6) The need for national energy and water conservation; and

(7) Other factors the Secretary of Energy (Secretary) considers relevant.

(42 U.S.C. 6295(o)(2)(B)(i)(I)-(VII))

Further, EPCA establishes a rebuttable presumption that a standard is economically justified if the Secretary finds that the additional cost to the consumer of purchasing a product complying with an energy conservation standard level will be less than three times the value of the energy savings during the first year that the consumer will receive as a result of the standard, as calculated under the applicable test procedure. (42 U.S.C. 6295(o)(2)(B)(iii))

EPCA also contains what is known as an “anti-backsliding” provision, which prevents the Secretary from prescribing any amended standard that either increases the maximum allowable energy use or decreases the minimum required energy efficiency of a covered product. (42 U.S.C. 6295(o)(1)) Also, the Secretary may not prescribe an amended or new standard if interested persons have established by a preponderance of the evidence that the standard is likely to result in the unavailability in the United States in any covered product type (or class) of performance characteristics (including reliability), features, sizes, capacities, and volumes that are substantially the same as those generally available in the United States. (42 U.S.C. 6295(o)(4))

Additionally, EPCA specifies requirements when promulgating an energy conservation standard for a covered product that has two or more subcategories. DOE must specify a different standard level for a type or class of product that has the same function or intended use, if DOE determines that products within such group: (A) consume a different kind of energy from that consumed by other covered products within such type (or class); or (B) have a capacity or other performance-related feature which other products within such type (or class) do not have and such feature justifies a higher or lower standard. (42 U.S.C. 6295(q)(1)) In determining whether a performance-related feature justifies a different standard for a group of products, DOE must consider such factors as the utility to the consumer of the feature and other factors DOE deems appropriate.

Id.

Any rule prescribing such a standard must include an explanation of the basis on which such higher or lower level was established. (42 U.S.C. 6295(q)(2))

Finally, pursuant to the amendments contained in the Energy Independence and Security Act of 2007 (EISA 2007), Pub. L. 110-140, any final rule for new or amended energy conservation standards promulgated after July 1, 2010, is required to address standby mode and off mode energy use. (42 U.S.C. 6295(gg)(3)) Specifically, when DOE adopts a standard for a covered product after that date, it must, if justified by the criteria for adoption of standards under EPCA (42 U.S.C. 6295(o)), incorporate standby mode and off mode energy use into a single standard, or, if that is not feasible, adopt a separate standard for such energy use for that product. (42 U.S.C. 6295(gg)(3)(A)-(B)) DOE's current test procedures for consumer boilers address standby mode and off mode energy use in separate metrics (P

W,SB

and P

W,OFF

, respectively). In this proposed rulemaking, DOE intends to consider these metrics in addition to the active mode metric, AFUE.

B. Background

1. Current Standards

In a final rule published in the

Federal Register

on January 15, 2016 (January 2016 Final Rule), DOE prescribed the current energy conservation standards for consumer boilers manufactured on and after January 15, 2021. 81 FR 2320, 2416-2417. These standards are set forth in DOE's regulations at 10 CFR 430.32(e)(2)(iii) and are repeated in Table II.1.

Table II.1—Federal Energy Conservation Standards for Consumer Boilers *

Product class

AFUE

(percent) **

W,SB

(watts) †

W,OFF

(watts) †

Design requirements

Gas-fired Hot Water

Constant-burning pilot not permitted. Automatic means for adjusting water temperature required (except for boilers equipped with tankless domestic water heating coils).

Gas-fired Steam

Constant-burning pilot not permitted.

Oil-fired Hot Water

Automatic means for adjusting temperature required (except for boilers equipped with tankless domestic water heating coils).

Oil-fired Steam

None.

Electric Hot Water

None

Automatic means for adjusting temperature required (except for boilers equipped with tankless domestic water heating coils).

Electric Steam

None

None.

* A boiler that is manufactured to operate without any need for electricity or any electric connection, electric gauges, electric pumps, electric wires, or electric devices is not required to meet the AFUE or design requirements. Instead, such boilers must meet a minimum AFUE of 80 percent (for all classes except gas-fired steam), and 75 percent for gas-fired steam.

** AFUE stands for Annual Fuel Utilization Efficiency, as determined in 10 CFR 430.23(n)(2).

† P

W,SB

and P

W,OFF

stand for standby mode power consumption and off mode power consumption, respectively.

2. History of Standards Rulemaking for Consumer Boilers

DOE initiated this rulemaking pursuant to its six-year-lookback authority under 42 U.S.C. 6295(m)(1). On March 25, 2021, DOE published in the

Federal Register

a request for information (RFI) that initiated an early assessment review to determine whether any new or amended standards would satisfy the relevant requirements of EPCA for a new or amended energy conservation standard for consumer boilers (March 2021 RFI). 86 FR 15804. Specifically, through the March 2021 RFI, DOE sought data and information that could enable the agency to determine whether DOE should propose a “no new standard” determination because a more-stringent standard: (1) would not result in a significant savings of energy; (2) is not technologically feasible; (3) is not economically justified; or (4) any combination of foregoing.

Id.

Additionally, DOE granted a 30-day comment extension for the March 2021 RFI (for a total of a 60-day comment period) in a notice published in the

Federal Register

on April 9, 2021. 86 FR 18478, 18479.

Subsequently, on May 4, 2022, DOE published in the

Federal Register

a preliminary analysis and TSD for purposes of evaluating the need for amended energy conservation standards for consumer boilers (May 2022 Preliminary Analysis). 87 FR 26304. The May 2022 Preliminary Analysis and TSD discussed the analytical framework, models, and tools used to evaluate potential standards, and the results of the preliminary analyses performed.

Id.

DOE held a public meeting webinar on June 16, 2022, to receive comments on its May 2022 Preliminary Analysis for consumer boilers.

DOE received comments in response to the May 2022 Preliminary Analysis from the interested parties listed in Table II.2.

Table II.2—May 2022 Preliminary Analysis Written Comments *

Commenter(s)

Abbreviation

Comment No. in the docket

Commenter type

American Gas Association, American Public Gas Association, National Propane Gas Association

AGA, APGA, and NPGA

Utility Trade Associations.

Air-Conditioning, Heating, and Refrigeration Institute

AHRI

40, 42

Manufacturer Trade Association.

Bradford White Corporation

BWC

Manufacturer.

Crown Boiler Company

Crown

Manufacturer.

Appliance Standards Awareness Project, American Council for an Energy-Efficient Economy, Consumer Federation of America, National Consumer Law Center, Natural Resources Defense Council

Joint Advocates

Efficiency Advocacy Organizations.

Northwest Energy Efficiency Alliance

NEEA

Efficiency Advocacy Organization.

New York State Energy Research and Development Authority

NYSERDA

State Agency.

PB Heat, LLC

PB Heat

Manufacturer.

Rheem Manufacturing Company

Rheem

Manufacturer.

U.S. Boiler Company, Inc

U.S. Boiler

Manufacturer.

Weil-McLain Technologies

WMT

Manufacturer.

* DOE received one additional comment to this docket that was not accessible and is not discussed further.

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

To the extent that interested parties have provided written comments that are substantively consistent with any oral comments provided during the June 16, 2022 Preliminary Analysis public meeting webinar, DOE cites the written comments throughout this document.

The parenthetical reference provides a reference for information located in the docket of DOE's rulemaking to develop energy conservation standards for consumer boilers. (Docket No. EERE-2019-BT-STD-0036, which is maintained at

www.regulations.gov

). The references are arranged as follows: (commenter name, comment docket ID number, page of that document).

C. Deviation From Appendix A

In accordance with section 3(a) of 10 CFR part 430, subpart C, appendix A (appendix A), DOE notes that it deviated from the provision at section 6(a)(2) in appendix A regarding the pre-NOPR stages for an energy conservation standards rulemaking (specifically, the publication of a framework document). As initially discussed in the May 2022 Preliminary Analysis, DOE opted to deviate from this step by publishing a preliminary analysis without a framework document. A framework document is intended to introduce and summarize the various analyses DOE conducts during the rulemaking process and requests initial feedback from interested parties. As noted in the May 2022 Preliminary Analysis, prior to that document, DOE published an RFI in the

Federal Register

in which DOE identified and sought comment on the analyses conducted in support of the most recent energy conservation standards rulemakings for boilers. 87 FR 26304, 26307 (May 4, 2022).

In accordance with section 3(a) of appendix A, DOE notes that it is deviating from the provision in appendix A specifying that there will not be less than 75 days for public comment on the NOPR (section 6(f)(2) of appendix A). The public comment period on this NOPR will be 60 days. DOE is opting to deviate from this step because the May 2022 Preliminary Analysis already allowed stakeholders an opportunity to comment on the analytical methods and subsequent preliminary results. Additionally, DOE extended the comment period for the March 2021 RFI by 30 days for a total of a 60-day comment period. 86 FR 18478, 18479 (April 9, 2021). This NOPR relies on the same overall approach, but has updated the analyses to incorporate stakeholder feedback in response to the preliminary results. Consequently, DOE has concluded that that a comment period of 60 days is appropriate and will provide interested parties a meaningful opportunity to comment on the proposed rule.

DOE notes that it is not deviating from the provisions in section 8(d)(1) of appendix A, which state that a test procedure final rule should be published at least 180 days prior to the close of a comment period of a NOPR proposing amended standards for the products within the scope of the test procedure final rule. Specifically, section 8(d)(1) pertains to test procedure amendments that impact measured energy use or efficiency. Most recently, DOE published a test procedure final rule in the

Federal Register

on March 13, 2023. 88 FR 15510. In this final rule, DOE concluded that the updates to the test procedure have minimal impact on AFUE ratings and that manufacturers will be able to rely on data generated under the previous version of that test procedure. Thus, an analysis of potential amended energy conservation standards for consumer boilers can be carried out using current performance data, so the 180-day requirement does not apply.

III. General Discussion

DOE developed this proposal after considering oral and written comments, data, and information from interested parties that represent a variety of interests. The following discussion addresses issues raised by these commenters.

A. General Comments

This section summarizes general comments received from interested parties regarding rulemaking timing and process.

AGA, APGA, and NPGA requested that DOE host a workshop to walk through the Department's analytical approach for stakeholders and the public in general, because these commenters suggested that the TSDs and associated spreadsheets are complex and appear not to be consistent across product categories. (AGA, APGA, NPGA, No. 38 at p. 4)

In response, DOE notes that the Department posts its TSDs and spreadsheet analyses to the rulemaking docket found at

regulations.gov

in order to provide transparency into the methodology used to arrive at the results presented in this NOPR. As stated in the

DATES

section of this proposed rule, DOE will host a public meeting via webinar which will include an overview of DOE's methodology and provide an opportunity for stakeholders to provide additional comments or pose questions on this topic.

Crown and U.S. Boiler stated that a 60-day comment period was insufficient to review the May 2022 Preliminary Analysis, given that several calculations and underlying assumptions have changed since the previous rulemaking. (Crown, No. 30 at p. 2; U.S. Boiler, No. 31 at p. 1)

As explained in the May 2022 Preliminary Analysis, DOE opted to provide a 60-day comment period because the Department had already requested comment in the March 2021 RFI on its energy conservation standards analyses. DOE incorporated then most recent data inputs but largely relied on many of the same analytical assumptions and approaches used in the previous rulemaking, such that the agency determined that a 60-day comment period in conjunction with the prior comment period for the March 2021 RFI provided sufficient time for interested parties to review the preliminary analysis and develop comments. 87 FR 26304, 26307 (May 4, 2022). Further, DOE notes that it is providing an additional 60-day comment period for this NOPR, which again relies on the same analytical structure as the May 2022 Preliminary Analysis.

B. Scope of Coverage

Consumer boilers are appliances that transfer heat using combustion gases or electricity to water to provide hot water or steam for space heating.

Consumer boilers are defined in EPCA as a type of furnace. Specifically, the term “furnace” is defined as a product which utilizes only single-phase electric current, or single-phase electric current or direct current in conjunction with natural gas, propane, or home heating oil, and which—

Is designed to be the principal heating source for the living space of a residence;

Is not contained within the same cabinet with a central air conditioner whose rated cooling capacity is above 65,000 Btu per hour (Btu/h);

Is an electric central furnace, electric boiler, forced-air central furnace, gravity central furnace, or low pressure steam or hot water boiler; and

Has a heat input rate of less than 300,000 Btu/h for electric boilers and low pressure steam or hot water boilers and less than 225,000 Btu/h for forced-air central furnaces, gravity central furnace, and electric central furnaces. (42 U.S.C. 6291(23))

DOE has codified definitions for the terms “electric boiler” and “low pressure steam or hot water boiler” in its regulations as follows:

Electric boiler

means an electrically powered furnace designed to supply low pressure steam or hot water for space heating application. A low pressure steam boiler operates at or below 15 pounds per square inch gauge (psig) steam pressure; a hot water boiler operates at or below 160 psig water pressure and 250 degrees Fahrenheit (°F) water temperature.

Low pressure steam or hot water boiler

means an electric, gas, or oil-burning furnace designed to supply low pressure steam or hot water for space heating application. A low pressure steam boiler operates at or below 15 psig steam pressure; a hot water boiler operates at or below 160 psig water pressure and 250 °F water temperature.

10 CFR 430.2.

In the May 2022 Preliminary Analysis, DOE requested comment on hydronic heat pumps as technology options for consumer boilers. (

See

the Executive Summary of the preliminary analysis TSD). In response, the Department received multiple comments regarding the classification of hydronic heat pump boilers. Hydronic heat pumps, commonly air-to-water heat pumps, are systems that use the refrigeration cycle to heat or chill water for domestic hot water or space conditioning use.

Crown and U.S. Boiler stated that heat pumps should not be classified as boilers due to their inability to generate water temperatures high enough to satisfy the design heating load of the vast majority of the residential hot water heating systems in the United States. (Crown, No. 30 at p. 3; U.S. Boiler, No. 31 at p. 3) BWC also disagreed with DOE's interpretation in the May 2022 Preliminary Analysis that air-to-water and water-to-water heat pumps (heat pump products) should be considered as consumer boilers, stating that heat pump products have pronounced differences that separate them from boilers. BWC also claimed that DOE has listed the two products separately on their website, as well as in DOE's Compliance Certification Management System (CCMS) database. (BWC, No. 39 at p. 1) AHRI similarly commented that heat pumps should not be included under the current regulatory definitions for boilers and boiler product classes, as the products cannot reach the same water temperature as conventional boilers and cannot provide sufficient heating year-round without assistance. AHRI recommended DOE update the current definition of a “boiler” to include the ability to provide the required heat on the coldest day of the year. AHRI further recommended that given the difference in the form, fit, and function of heat pumps and conventional boilers, DOE should establish a separate definition and product class for these heat pump products. (AHRI, No. 40 at p. 3)

In contrast, Rheem, NYSERDA, the Joint Advocates, and NEEA all suggested that heat pump boilers are capable of meeting home heating design loads and should be considered as consumer boilers. (Rheem, No. 37 at p. 3; NYSERDA, No. 33 at p. 2; Joint Advocates, No. 35 at pp. 1-2; NEEA, No. 36 at pp. 1-2) Rheem also stated that while heat pumps may not reach the same maximum temperatures as conventional products, heat pumps can provide adequate space heating in many applications. (Rheem, No. 37 at p. 2)

In the March 2023 TP Final Rule, which was the most recent rulemaking amending the consumer boiler test procedure, DOE addressed similar comments suggesting hydronic air-to-water heat pump boilers and water-to-water heat pump boilers should be excluded from the “boiler” definitions because they cannot provide the same maximum water temperature as non-heat pump hydronic systems. Specifically, in the March 2023 TP Final Rule, DOE noted that neither the EPCA definition nor DOE's definitions at 10 CFR 430.2 for consumer boilers provide a minimum water temperature requirement and, thus, do not exclude hydronic heat pump boilers from being considered as consumer boilers. DOE also noted in the March 2023 TP Final Rule that hydronic heat pump boilers are marketed as providing the principal heating source for a residence. 88 FR 15510, 15515-15516 (March 13, 2023).

In response to the comments received on the May 2022 Preliminary Analysis, DOE again reviewed the market for hydronic heat pumps. Based on its review of the hydronic heat pumps currently on the market, DOE agrees with Rheem, NYSERDA, the Joint Advocates, and NEEA that hydronic heat pumps can provide enough space heating to serve home design loads in many applications. These products utilize only single-phase electric current or direct current in conjunction with natural gas, propane, or home heating oil, can be designed to be the principal heating source for the living space of a residence, are not contained within the same cabinet with a central air conditioner whose rated cooling capacity is above 65,000 Btu/h, meet the definition of an “electric boiler,” and have a heat input rate of less than 300,000 Btu/h (

i.e.,

the requirement for electric boilers). As such, hydronic heat pumps which are designed to be the principal heating source of the living

space of a residence meet the criteria of “furnace” as defined in EPCA at 42 U.S.C. 6291(23). Further, the Department notes that these products also meet DOE's codified regulatory definition for “low pressure steam or hot water boiler.” Therefore, DOE considers hydronic heat pumps to be within the scope of coverage for consumer boilers. However, as discussed in section III.C of this document, there is no currently-applicable test procedure for hydronic heat pump consumer boilers, and as a result, DOE has not considered these products further in this NOPR.

In this NOPR, DOE has considered products which meet the definitions for “electric boiler” and “low pressure steam or hot water boiler” to be consumer boilers within the scope of this rulemaking, with the exception of hydronic heat pump boilers, for which there is currently no applicable test procedure to determine compliance with standards.

See section IV.A.1 of this document for discussion of the product classes analyzed in this NOPR.

C. Test Procedure

EPCA sets forth generally applicable criteria and procedures for DOE's adoption and amendment of test procedures. (42 U.S.C. 6293) Manufacturers of covered products must use these test procedures to quantify the efficiency of their product, to certify to DOE that their product complies with energy conservation standards, and when making efficiency-related representations to the public. (42 U.S.C. 6293(c) and 42 U.S.C. 6295(s)) EPCA states that the AFUE is the efficiency descriptor for furnaces and boilers (

See

42 U.S.C. 6291(20) and (22)); however, as discussed in section II.A of this document, DOE is required to also account for standby mode and off mode energy consumption. Accordingly, for the current consumer boiler energy conservation standards, AFUE is the active mode efficiency metric, while P

W,SB

and P

W,OFF

are the metrics for standby mode and off mode electrical energy consumption, respectively (

see

10 CFR 430.32(e)(2)(iii)). All three of these metrics are measured by the DOE test procedure for consumer boilers.

On March 13, 2023, DOE published a final rule in the

Federal Register

amending the test procedure for consumer boilers (March 2023 TP Final Rule). 88 FR 15510. The amended test procedure became effective on April 12, 2023.

Prior to April 12, 2023, the DOE test procedure for determining the AFUE, P

W,SB

, and P

W,OFF

of consumer boilers was located at appendix N to subpart B of 10 CFR part 430 (appendix N) and referenced American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 103-1993, “Method of Testing for Annual Fuel Utilization Efficiency of Residential Central Furnaces and Boilers”

and International Electrotechnical Commission (IEC) 62301 (Edition 2.0), “Household electrical appliances—Measurement of standby power.” AFUE is an annualized fuel efficiency metric that fully accounts for fuel consumption in active, standby, and off modes but does not include auxiliary electrical energy consumption. P

W,SB

and P

W,OFF

are measures of the standby mode and off mode power consumption, respectively, in watts.

American Society for Testing and Materials (ASTM) Standard D2159-09 (Reapproved 2013), “Standard test methods and procedures for Smoke Density in Flue Gases From Burning Distillate Fuels,” (ASTM D2156-09 (R2013)) is also referenced by the appendix EE test procedure for setting up oil-fired burners.

In the March 2023 TP final rule, DOE updated appendix N to remove the provisions applicable only to consumer boilers and to rename the appendix “Uniform Test Method for Measuring the Energy Consumption of Furnaces.” Correspondingly, the final rule established a new test procedure specific to consumer boilers in a new appendix EE to subpart B of 10 CFR part 430 (appendix EE). On and after September 11, 2023, manufacturers will be required to use the amended test procedure (though manufacturers may opt to do so early (

i.e.,

any time after April 12, 2023)), per the March 2023 TP Final Rule, to determine ratings for consumer boilers. The amended test procedure located at appendix EE consists of all provisions that were previously included in appendix N relevant to consumer boilers, with the following modifications:

Incorporating by reference the current revision to the applicable industry standard, American National Standards Institute (ANSI)/ASHRAE Standard 103-2017, “Methods of Testing for Annual Fuel Utilization Efficiency of Residential Central Furnaces and Boilers;”

Incorporating by reference the current revision of American Society for Testing and Materials (ASTM) Standard D2156-09 (Reapproved 2018), “Standard Test Method for Smoke Density in Flue Gases from Burning Distillate Fuels;”

Incorporating by reference ANSI/ASHRAE Standard 41.6-2014, “Standard Method for Humidity Measurement;”

Updating the definitions to reflect the changes in ANSI/ASHRAE 103-2017 as compared to ANSI/ASHRAE 103-1993;

Removing the definition of “outdoor furnace or boiler” from 10 CFR 430.2;

Making certain corrections to improve the accuracy, repeatability, and reproducibility of calculations within the test procedure.

88 FR 15510, 15512-15513 (March 13, 2023).

DOE determined that the amendments in the March 2023 TP Final Rule would minimally impact the measured efficiency of certain consumer boilers, and retesting and re-rating would not be required. 88 FR 15510, 15514 (March 13, 2023). Therefore, DOE expects that the energy efficiency and energy consumption ratings currently achieved are still representative of ratings that would be achieved under the revised test method. As a result, DOE evaluated potential amended energy conservation standards for consumer boilers using current market data.

As discussed in section III.B of this document, DOE has become aware of hydronic air-to-water and water-to-water heat pumps, which DOE has determined meet the definitional criteria to be classified as consumer boilers. However, the AFUE metric described in ASHRAE 103-2017 (which is incorporated by reference into appendix EE) calculates the efficiency of an electric boiler as 100 percent minus jacket loss,

which provides a representative measure of efficiency for electric boilers using electric resistance technology, for which an efficiency value of 100 percent (the ratio of heat output to energy input) is the maximum upper limit that technically could be achieved. DOE concluded that the AFUE metric would not provide a representative or meaningful measure of efficiency for a boiler with a heat pump supplying the heat input, because heat pump efficiency (in terms of heat output to energy input) typically exceeds 100 percent, and the AFUE metric does not allow for ratings greater than 100 percent for electric boilers. 88 FR 15510, 15515 (March 13, 2023). Similarly, the ASHRAE 103-2017 test procedure assumes a maximum value of 100 percent for gas-fired and oil-fired boilers when calculating the steady-state efficiency and heating seasonal efficiency, such that the methodology would not result in representative AFUE

values for gas-fired or oil-fired absorption heat pump boilers.

The term “jacket loss” is used by industry to mean the transfer of heat from the outer surface (

i.e.,

jacket) of a boiler to the ambient air surrounding the boiler.

Rheem, NYSERDA, the Joint Advocates, and NEEA all urged DOE to develop a test procedure for heat pump consumer boilers. (Rheem, No. 37 at p. 3; NYSERDA, No. 33 at p. 2; Joint Advocates, No. 35 at p. 2; NEEA, No. 36 at p. 2)

DOE will consider heat pump boilers when re-evaluating the test procedure for consumer boilers in a future rulemaking. As noted in section III.B of this document, due to the lack of a Federal test procedure at this time which adequately addresses AFUE for heat pump boilers, DOE has initially determined not to analyze heat pump boilers in this standards rulemaking. However, the standby mode and off mode power consumption test procedures in appendix EE remain applicable to heat pump boilers; hence, these metrics are required for heat pump boilers. Similarly, the statutory design requirements at 10 CFR 430.32(e)(2)(iii)(A) apply to these products.

D. Boilers Not Requiring Electricity

On July 28, 2008, DOE published a final rule technical amendment in the

Federal Register

to codify the requirements that would be applicable to consumer boilers as established in the Energy Independence and Security Act of 2007. 73 FR 43611. That final rule codified, as per the statute, that a boiler that is manufactured to operate without any need for electricity or any electric connection, electric gauges, electric pumps, electric wires, or electric devices shall not be required to meet the current minimum AFUE standards or design requirements for consumer boilers.

Id.

at 73 FR 43613.

As a result of this statutory exception, the regulations require that boilers manufactured to operate without any need for electricity or any electric connection, electric gauges, electric pumps, electric wires, or electric devices must still meet the minimum AFUE requirements in 10 CFR 430.32(e)(2)(i)—namely, a minimum AFUE of 80 percent (for all classes except gas-fired steam boilers), and 75 percent for gas-fired steam boilers.

In subsequent final rules, including the January 2016 final rule, DOE maintained this exception for boilers not requiring electricity as required by EPCA; however, the codified language had a technical error wherein the exception inadvertently only applied to boilers manufactured on or after September 1, 2012, and before January 15, 2021 (see 10 CFR 430.32(e)(2)(v), which only references 10 CFR 430.32(e)(2)(ii)). The provisions at 10 CFR 430.32(e)(2)(v) apply also to boilers manufactured on or after January 15, 2021 (which must meet the requirements at 10 CFR 430.32(e)(2)(iii)).

In this NOPR, DOE proposes to make technical amendments to the standards for consumer boilers to clarify that the aforementioned exceptions continue to apply.

E. Technological Feasibility

1. General

In each energy conservation standards rulemaking, DOE conducts a screening analysis based on information gathered on all current technology options and prototype designs that could improve the efficiency of the products or equipment that are the subject of the rulemaking. As the first step in such an analysis, DOE develops a list of technology options for consideration in consultation with manufacturers, design engineers, and other interested parties. DOE then determines which of those means for improving efficiency are technologically feasible. DOE considers technologies incorporated in commercially-available products or in working prototypes to be technologically feasible. Sections 6(b)(3)(i) and 7(b)(1) of appendix A.

After DOE has determined that particular technology options are technologically feasible, it further evaluates each technology option in light of the following additional screening criteria: (1) practicability to manufacture, install, and service; (2) adverse impacts on product utility or availability; (3) adverse impacts on health or safety, and (4) unique-pathway proprietary technologies. Sections 6(b)(3)(ii)-(v) and 7(b)(2)-(5) of appendix A. Section IV.B of this document discusses the results of the screening analysis for consumer boilers, particularly the designs DOE considered, those it screened out, and those that are the basis for the potential standards considered in this rulemaking. For further details on the screening analysis for this rulemaking, see chapter 4 of the NOPR TSD.

2. Maximum Technologically Feasible Levels

When DOE proposes to adopt an amended standard for a type or class of covered product, it must determine the maximum improvement in energy efficiency or maximum reduction in energy use that is technologically feasible for such product. (42 U.S.C. 6295(p)(1)) Accordingly, in the engineering analysis, DOE determined the maximum technologically feasible (“max-tech”) improvements in energy efficiency for consumer boilers, using the design parameters for the most efficient products available on the market or in working prototypes. The max-tech levels that DOE determined for this rulemaking are described in section IV.C.1.b of this document and in chapter 5 of the NOPR TSD.

F. Energy Savings

1. Determination of Savings

For each TSL, DOE projected energy savings from application of the TSL to consumer boilers purchased in the 30-year period that begins in the year of compliance with the proposed standards (2030-2059).

The savings are measured over the entire lifetime of consumer boilers purchased in the previous 30-year period. DOE quantified the energy savings attributable to each TSL as the difference in energy consumption between each standards case and the no-new-standards case. The no-new-standards case represents a projection of energy consumption that reflects how the market for a product would likely evolve in the absence of new or amended energy conservation standards.

Each TSL is composed of specific efficiency levels for each product class. The TSLs considered for this NOPR are described in section V.A of this document. DOE conducted a sensitivity analysis that considers impacts for products shipped in a 9-year period.

DOE used its national impact analysis (NIA) spreadsheet model to estimate national energy savings (NES) from potential amended or new standards for consumer boilers. The NIA spreadsheet model (described in section IV.H of this document) calculates energy savings in terms of site energy, which is the energy directly consumed by products at the locations where they are used. For electricity, DOE reports national energy savings in terms of primary energy savings, which is the savings in the energy that is used to generate and transmit the site electricity. For natural gas, the primary energy savings are considered to be equal to the site energy savings. DOE also calculates NES in terms of FFC energy savings. The FFC metric includes the energy consumed in extracting, processing, and transporting primary fuels (

i.e.,

coal, natural gas, petroleum fuels), and, thus, presents a more complete picture of the impacts of energy conservation standards.

DOE's approach is based on the calculation of an FFC multiplier for each of the energy

types used by covered products or equipment. For more information on FFC energy savings, see section IV.H.2 of this document.

The FFC metric is discussed in DOE's statement of policy and notice of policy amendment. 76 FR 51281 (August 18, 2011), as amended at 77 FR 49701 (August 17, 2012).

2. Significance of Savings

To adopt any new or amended standards for a covered product, DOE must determine that such action would result in significant energy savings. (42 U.S.C. 6295(o)(3)(B))

The significance of energy savings offered by a new or amended energy conservation standard cannot be determined without knowledge of the specific circumstances surrounding a given rulemaking.

For example, some covered products and equipment have most of their energy consumption occur during periods of peak energy demand. The impacts of these products on the energy infrastructure can be more pronounced than products with relatively constant demand. Accordingly, DOE evaluates the significance of energy savings on a case-by-case basis, taking into account the significance of cumulative FFC national energy savings, the cumulative FFC emissions reductions, and the need to confront the global climate crisis, among other factors. DOE has initially determined the energy savings from the proposed standard levels are “significant” within the meaning of 42 U.S.C. 6295(o)(3)(B).

The numeric threshold for determining the significance of energy savings, established in a final rule published in the

Federal Register

on February 14, 2020 (85 FR 8626, 8670), was subsequently eliminated in a final rule published in the

Federal Register

on December 13, 2021 (86 FR 70892, 70906), which went into effect on January 12, 2022.

G. Economic Justification

1. Specific Criteria

As noted previously, EPCA provides seven factors to be evaluated in determining whether a potential energy conservation standard is economically justified. (42 U.S.C. 6295(o)(2)(B)(i)(I)-(VII)) The following sections discuss how DOE has addressed each of those seven factors in this proposed rulemaking.

a. Economic Impact on Manufacturers and Consumers

In determining the impacts of a potential amended standard on manufacturers, DOE conducts an MIA, as discussed in section IV.J of this document. DOE first uses an annual cash-flow approach to determine the quantitative impacts. This step includes both a short-term assessment—based on the cost and capital requirements during the period between when a regulation is issued and when entities must comply with the regulation—and a long-term assessment over a 30-year period. The industry-wide impacts analyzed include: (1) INPV, which values the industry on the basis of expected future cash flows, (2) cash flows by year, (3) changes in revenue and income, and (4) other measures of impact, as appropriate. Second, DOE analyzes and reports the impacts on different types of manufacturers, including impacts on small manufacturers. Third, DOE considers the impact of standards on domestic manufacturer employment and manufacturing capacity, as well as the potential for standards to result in plant closures and loss of capital investment. Finally, DOE takes into account cumulative impacts of various DOE regulations and other regulatory requirements on manufacturers.

For individual consumers, measures of economic impact include the changes in LCC and PBP associated with new or amended standards. These measures are discussed further in the following section. For consumers in the aggregate, DOE also calculates the national net present value of the consumer costs and benefits expected to result from particular standards. DOE also evaluates the impacts of potential standards on identifiable subgroups of consumers that may be affected disproportionately by a standard.

b. Savings in Operating Costs Compared To Increase in Price (LCC and PBP)

EPCA requires DOE to consider the savings in operating costs throughout the estimated average life of the covered product in the type (or class) compared to any increase in the price of, or in the initial charges for, or maintenance expenses of, the covered product that are likely to result from a standard. (42 U.S.C. 6295(o)(2)(B)(i)(II)) DOE conducts this comparison in its LCC and PBP analysis.

The LCC is the sum of the purchase price of a product (including its installation) and the operating expense (including energy, maintenance, and repair expenditures) discounted over the lifetime of the product. The LCC analysis requires a variety of inputs, such as product prices, product energy consumption, energy prices, maintenance and repair costs, product lifetime, and discount rates appropriate for consumers. To account for uncertainty and variability in specific inputs, such as product lifetime and discount rate, DOE uses a distribution of values, with probabilities attached to each value.

The PBP is the estimated amount of time (in years) it takes consumers to recover the increased purchase cost (including installation) of a more-efficient product through lower operating costs. DOE calculates the PBP by dividing the change in purchase cost due to a more-stringent standard by the change in annual operating cost for the year that standards are assumed to take effect.

For its LCC and PBP analysis, DOE assumes that consumers will purchase the covered products in the first year of compliance with new or amended standards. The LCC savings for the considered efficiency levels are calculated relative to the case that reflects projected market trends in the absence of new or amended standards. DOE's LCC and PBP analysis is discussed in further detail in section IV.F of this document.

c. Energy Savings

Although significant conservation of energy is a separate statutory requirement for adopting an energy conservation standard, EPCA requires DOE, in determining the economic justification of a standard, to consider the total projected energy savings that are expected to result directly from the standard. (42 U.S.C. 6295(o)(2)(B)(i)(III)) As discussed in section III.F.1 of this document, DOE uses the NIA spreadsheet models to project national energy savings.

d. Lessening of Utility or Performance of Products

In establishing product classes and in evaluating design options and the impact of potential standard levels, DOE evaluates potential standards that would not lessen the utility or performance of the considered products. (42 U.S.C. 6295(o)(2)(B)(i)(IV)) Based on data available to DOE, the standards proposed in this document would not reduce the utility or performance of the products under consideration in this rulemaking.

e. Impact of Any Lessening of Competition

EPCA directs DOE to consider the impact of any lessening of competition, as determined in writing by the Attorney General, that is likely to result from a proposed standard. (42 U.S.C. 6295(o)(2)(B)(i)(V)) It also directs the Attorney General to determine the impact, if any, of any lessening of competition likely to result from a proposed standard and to transmit such determination to the Secretary within 60 days of the publication of a proposed rule, together with an analysis of the nature and extent of the impact. (42 U.S.C. 6295(o)(2)(B)(ii)) DOE will transmit a copy of this proposed rule to

the Attorney General with a request that the Department of Justice (DOJ) provide its determination on this issue. DOE will publish and respond to the Attorney General's determination in the final rule. DOE invites comment from the public regarding the competitive impacts that are likely to result from this proposed rule. In addition, stakeholders may also provide comments separately to DOJ regarding these potential impacts. See the

ADDRESSES

section for information to send comments to DOJ.

f. Need for National Energy Conservation

DOE also considers the need for national energy and water conservation in determining whether a new or amended standard is economically justified. (42 U.S.C. 6295(o)(2)(B)(i)(VI)) The energy savings from the proposed standards are likely to provide improvements to the security and reliability of the Nation's energy system. Reductions in the demand for electricity also may result in reduced costs for maintaining the reliability of the Nation's electricity system. DOE conducts a utility impact analysis to estimate how standards may affect the Nation's needed power generation capacity, as discussed in section IV.M of this document.

DOE maintains that environmental and public health benefits associated with the more efficient use of energy are important to take into account when considering the need for national energy conservation. The proposed standards are likely to result in environmental benefits in the form of reduced emissions of air pollutants and GHGs associated with energy production and use. DOE conducts an emissions analysis to estimate how potential standards may affect these emissions, as discussed in section IV.K of this document; the estimated emissions impacts are reported in section V.B.6 of this document. DOE also estimates the economic value of emissions reductions resulting from the considered TSLs, as discussed in section IV.L of this document.

g. Other Factors

In determining whether an energy conservation standard is economically justified, DOE may consider any other factors that the Secretary deems to be relevant. (42 U.S.C. 6295(o)(2)(B)(i)(VII)) To the extent DOE identifies any relevant information regarding economic justification that does not fit into the other categories described previously, DOE could consider such information under “other factors.”

2. Rebuttable Presumption

As set forth in 42 U.S.C. 6295(o)(2)(B)(iii), EPCA creates a rebuttable presumption that an energy conservation standard is economically justified if the additional cost to the consumer of a product that meets the standard is less than three times the value of the first year's energy savings resulting from the standard, as calculated under the applicable DOE test procedure. DOE's LCC and PBP analyses generate values used to calculate the effects that proposed energy conservation standards would have on the payback period for consumers. These analyses include, but are not limited to, the 3-year payback period contemplated under the rebuttable-presumption test. In addition, DOE routinely conducts an economic analysis that considers the full range of impacts to consumers, manufacturers, the Nation, and the environment, as required under 42 U.S.C. 6295(o)(2)(B)(i). The results of this analysis serve as the basis for DOE's evaluation of the economic justification for a potential standard level (thereby supporting or rebutting the results of any preliminary determination of economic justification). The rebuttable presumption payback calculation is discussed in section IV.F.9 and results reported in section V.B.1.c of this document.

IV. Methodology and Discussion of Related Comments

This section addresses the analyses DOE has performed for this rulemaking with regard to consumer boilers. Separate subsections address each component of DOE's analyses.

DOE used several analytical tools to estimate the impact of the standards proposed in this document. The first tool is a spreadsheet that calculates the LCC savings and PBP of potential amended or new energy conservation standards. The national impacts analysis uses a second spreadsheet set that provides shipments projections and calculates national energy savings and net present value of total consumer costs and savings expected to result from potential energy conservation standards. DOE uses the third spreadsheet tool, the Government Regulatory Impact Model (GRIM), to assess manufacturer impacts of potential standards. These three spreadsheet tools are available on the DOE website for this proposed rulemaking:

www1.eere.energy.gov/buildings/appliance_standards/standards.aspx?productid=45&action=viewcurrent.

Additionally, DOE used output from the latest version of the Energy Information Administration's (EIA's)

Annual Energy Outlook

(

AEO

), a widely known energy projection for the United States, for the emissions and utility impact analyses.

A. Market and Technology Assessment

DOE develops information in the market and technology assessment that provides an overall picture of the market for the products concerned, including the purpose of the products, the industry structure, manufacturers, market characteristics, and technologies used in the products. This activity includes both quantitative and qualitative assessments, based primarily on publicly-available information. The subjects addressed in the market and technology assessment for this proposed rulemaking include: (1) a determination of the scope of the rulemaking and product classes, (2) manufacturers and industry structure, (3) existing efficiency programs, (4) shipments information, (5) market and industry trends; and (6) technologies or design options that could improve the energy efficiency of consumer boilers. The key findings of DOE's market assessment are summarized in the following sections.

See

chapter 3 of the NOPR TSD for further discussion of the market and technology assessment.

1. Product Classes

When evaluating and establishing energy conservation standards, DOE may establish separate standards for a group of covered products (

i.e.,

establish a separate product class) if DOE determines that separate standards are justified based on the type of energy used, or if DOE determines that a product's capacity or other performance-related feature justifies a different standard. (42 U.S.C. 6295(q)) In making a determination whether a performance-related feature justifies a different standard, DOE must consider such factors as the utility of the feature to the consumer and other factors DOE determines are appropriate. (

Id.

)

The current product classes are divided by the type of energy used (

i.e.,

gas, oil, or electricity) and by the heat transfer medium (

i.e.,

steam or hot water) as shown in Table IV.1. (

See

10 CFR 430.32(e)(2)) The current product classes were originally established by EISA 2007 and are codified at 10 CFR 430.32(e)(2)(iii)(A).

Table IV.1—Consumer Boiler Product Classes

Fuel type

Heat transfer medium

Gas

Steam.

Hot Water.

Oil

Steam.

Hot Water.

Electric

Steam.

Hot Water.

In the May 2022 Preliminary Analysis, DOE maintained these product classes, and the Department solicited feedback on whether any additional product classes would be necessary for consumer boilers, including a potential consideration for hydronic heat pump boilers. (

See

the Executive Summary of the preliminary analysis TSD). Multiple stakeholders provided feedback on potential additional product classes for fossil fuel-fired hot water boilers and hydronic heat pump boilers, as discussed in the subsections that follow.

a. Fossil Fuel-Fired Hot Water Boilers

As discussed in chapter 3 of the NOPR TSD, due to the high temperature of steam, condensing operation is not utilized in steam boilers, and all steam boilers on the market are non-condensing. Therefore, the discussion in this section is only applicable to hot water boilers.

On December 29, 2021, DOE published in the

Federal Register

a final interpretive rule for consumer furnaces, commercial water heaters, and similarly situated products or equipment (the December 2021 Interpretive Rule), which explained DOE's return to its historic position that, among other things, non-condensing technology and associated venting of the flue gases is not a performance-related “feature” that provides a distinct consumer utility under EPCA.

86 FR 73947.

For more information, see

www.regulations.gov/docket/EERE-2018-BT-STD-0018

(Last accessed Jan. 3, 2023).

In the May 2022 Preliminary Analysis, DOE addressed several comments on the March 2021 RFI from stakeholders requesting that the Department consider non-condensing technology and associated venting to be a performance-related feature, (see chapter 2 of the preliminary TSD), and DOE maintained its position that non-condensing technology does not constitute a performance-related “feature,” consistent with the December 2021 Interpretive Rule. 87 FR 26304, 26308 (May 4, 2022). In response to the May 2022 Preliminary Analysis, commenters provided follow-up feedback with more information regarding how condensing versus non-condensing technology would affect the applicable venting categories.

As discussed in chapter 3 of the NOPR TSD, manufacturers generally provide specific venting instructions based on the characteristics of the heating appliance. The National Fire Protection Association (NFPA) and ANSI maintain NFPA 54/ANSI Z223.1, “National Fuel Gas Code,” which assigns four venting categories to gas-fired appliances. Category I venting is for nonpositive vent static pressures

and limited flue gas condensate

production in the vent; Category II venting is for nonpositive vent static pressures and excessive condensate production in the vent; Category III venting is for positive vent static pressures and limited condensate production in the vent, and Category IV venting is for positive vent static pressures and excessive condensate production in the vent. Non-condensing boilers can use Category I venting, which is compatible with natural draft vent systems that use chimney venting, but condensing boilers require category IV venting, which is not compatible with natural draft vent systems. (Category II venting is not common for consumer boilers, and Category III venting can be used for non-condensing boilers but is also not compatible with natural draft vent systems.)

Static pressure is the pressure created by a fluid at rest relative to the measurement instrument. Here non-positive static pressure refers to the flue gases having a pressure lower than atmospheric pressure so no assistance is needed for the flue gases to escape through the vent system.

Condensate refers to the moisture that condenses inside venting systems when the flue gas is cooled to below the dew point and liquid begins to condense on the walls of the vent system.

Crown and U.S. Boiler stated that the ability to vent residential boilers using Category I venting is a feature that must be preserved due to boilers being a primarily replacement market in older urban areas with limited exterior wall space suitable for a vent terminal, and they recommended that there should be a product class for Category I boilers. Crown stated that the elimination of Category I venting would result in the need for extensive renovations to some existing structures if the chimney can no longer be used, the potential for boilers to be used long after they are a safe option, the potential use of less safe heating equipment such as electric space heaters, or the possibility of poor venting reconfigurations that could lead to safety issues. Crown and U.S. Boiler stated that these ramifications cannot be addressed in the standards cost-benefit analysis. Crown and U.S. Boiler pointed to the preliminary TSD, which discussed that both the United Kingdom and European Union have exceptions to their condensing boiler standards that allow for installation of non-condensing boilers in difficult installation circumstances. (Crown, No. 30 at pp. 2-3; U.S. Boiler, No. 31 at p. 2)

WMT stated that it believes that EPCA (42 U.S.C. 6295(o)(4)) prohibits the elimination of non-condensing hot water boilers, and non-condensing operation constitutes a product feature per EPCA that warrants a separate product class under 42 U.S.C. 6295(q)(1), as stated by DOE in the January 2021 Interpretative Rule (86 FR 4776). (WMT, No. 32 at pp. 1-2) WMT suggested that non-condensing boilers in Category I venting should be a separate product class in order to recognize that these products operate at 180 °F return water temperatures, vent through Category I venting, and may be installed in insufficiently-insulated homes. WMT asserted that these homes also do not have the ability to increase heat emitter surface area, and, thus, the various efficiency levels analyzed in the preliminary analysis could not be achieved by this hypothetical new product class. (WMT, No. 32 at p. 7)

PB Heat advocated for a separate product class for non-condensing boilers, claiming that this action would secure cost-effective products for consumers, in terms of product lifespan and maintenance, as well as maintaining the consumer boiler replacement market. (PB Heat, No. 34 at p. 2)

In contrast, NYSERDA stated that condensing and non-condensing boilers should remain in the same product class because condensing operation is not a performance-related feature. NYSERDA indicated that challenging installations represent a small proportion of the market. NYSERDA provided data showing that almost 40 percent of all furnaces and boilers in New York achieve a condensing level of performance,

and commented that DOE's estimate that fewer than 5 percent of installations could be labeled as challenging is well-supported and reflective of the significant gain of market share that condensing products have achieved over the last twenty years. (NYSERDA, No. 33 at p. 3)

NYSERDA provided information from its 2019 Residential Building Stock Assessment, found online at

www.nyserda.ny.gov/About/Publications/Building-Stock-and-Potential-Studies/Residential-Building-Stock-Assessment

(Last accessed Jan. 3, 2023).

The Joint Advocates likewise supported DOE's decision to evaluate condensing and non-condensing boilers within a single product class (as

discussed in chapter 2 of the preliminary TSD). The Joint Advocates stated that condensing technology provides the same utility, uses the same fuel source, and does not constitute a “performance related feature” that would warrant a separate product class from non-condensing technology. (Joint Advocates, No. 35 at p. 1) NEEA also supported DOE's decision to evaluate condensing and non-condensing boilers within a single product class, as both products utilize the same primary fuel source, neither provides unique consumer utility, and keeping them in the same class prevents non-condensing boiler manufacturers from obtaining a competitive, regulatory advantage over condensing boiler manufacturers (

i.e.,

by having less-stringent requirements). (NEEA, No. 36 at p. 1)

With respect to commenters' statements that non-condensing technology and associated venting is a “feature” that DOE's standards cannot make unavailable, DOE concluded in the December 2021 final interpretive rule that incorporation of non-condensing technology and associated venting is not a performance-related “feature” for the purpose of the EPCA prohibition at 42 U.S.C. 6295(o)(4). 86 FR 73955 73947, 73955 (Dec. 29. 2021). In support of that conclusion, DOE explained that given EPCA's focus on an appliance's major function(s), it is reasonable to assume that the consumer would be aware of performance-related features and would recognize such features as providing additional benefit in the appliance's performance of such major function.

Id.

For example, some boilers have Wi-Fi connectivity features that allow the consumer to remotely monitor and control their boiler.

In contrast to these features, an aspect of the appliance that does not provide any additional benefit to the consumer during operation would not be a performance-related feature that Congress would expect DOE to preserve at the expense of energy savings. With respect to boilers, some examples are heat exchanger designs or materials, burner designs, and ignition system designs. While all of these components are necessary parts of a boiler, they are not performance-related features that provide other additional benefit to the consumer during operation. Non-condensing technology and associated venting falls squarely into this category. Further, energy conservation standards work by removing the less-efficient technologies and designs from the market. For example, DOE set standards for furnace fans in 2014 that effectively eliminated permanent split capacitor motors from several product classes in favor of brushless permanent magnet motors, which are more efficient. 79 FR 38130. As a second example, the amended standards for residential clothes washers established by the May 31, 2012, rule effectively eliminated the use of electromechanical-style user interface controls from the market, in favor of fully electronic user interface controls—which enable more efficient energy and water performance. 77 FR 32307. As a third example, DOE published a final rule on June 17, 2013, adopting energy conservation standards for microwave oven standby mode and off mode. These standards effectively eliminated the use of linear power supplies from microwave oven control boards, in favor of switch-mode power supplies, which exhibit significantly lower standby mode and off mode power consumption. 78 FR 36316. It would completely frustrate the energy-savings purposes of EPCA if DOE were to adopt an overly-broad reading of “features” that preserves less-efficient technologies without determining that boilers using those less-efficient technologies offer consumers an additional benefit during normal operation that other boilers do not offer.

For example, see:

https://www.viessmann-us.com/content/dam/public-brands/us/flyers/Vitodens_200_W_B2HE_06_2021.pdf/_jcr_content/renditions/original./Vitodens_200_W_B2HE_06_2021.pdf and https://ntiboilers.com/wp-content/uploads/2020/09/FTVN_Series-Handout_2020_Web.pdf.

For these reasons, DOE disagrees with commenters that eliminating non-condensing boiler technology and associated venting from the market would violate EPCA's “unavailability” provision as that technology does not provide unique utility to consumers that is not substantially the same as that provided by condensing boilers. Moreover, such a finding would preserve a less efficient technology with no unique consumer utility at the expense of a significant savings of energy and consumer benefit. Accordingly, for the purpose of the analysis conducted for this rulemaking, DOE did not analyze separate equipment classes for non-condensing and condensing boilers in this final rule.

In addition, while DOE agrees with NYSERDA that the number of challenging installations represent a decreasing proportion of the market because newer constructions can be designed around Category IV venting considerations, DOE also agrees with manufacturers that those few consumers with challenging installations could incur significant costs. But DOE does not agree with the assertion by Crown and U.S. Boiler that non-condensing technology and associated venting must be preserved because the costs of these challenging installations cannot be accounted for in DOE's economic analysis. First, as stated previously, non-condensing technology and associated venting is not a performance-related feature because, among other things, it does not provide additional benefit in the appliance's performance of its major function. Using existing venting can reduce installation costs, but that does not provide the consumer with any additional benefits during operation of the boiler. Further, EPCA specifically directs DOE to consider installation and operating costs as part of the Department's determination of economic justification. (See 42 U.S.C. 6295(o)(2)(B)(i)(II)) As a result, there is a clear distinction in EPCA between the purposes of the product class provision in 42 U.S.C. 6295(q)—preserve performance-related features in the market—and the economic justification requirement in 42 U.S.C. 6295(o)(2)(B)—determine whether the benefits,

e.g.,

reduced fuel costs for an appliance, of a proposed standard exceed the burdens,

e.g.,

increased installation cost. And, DOE has accounted for the costs of altering or replacing an existing venting system with a venting system that will accommodate a condensing furnace as part of the installation costs in the LCC analysis (see section IV.F.2 of this document and chapter 8 of the NOPR TSD).

With respect to Crown and U.S. Boiler's concerns regarding safety issues caused by condensing boilers, DOE is not aware of, nor have the commenters provided, any data showing that non-condensing boilers are a safer option than condensing boilers. DOE notes that condensing boilers are currently widely available on the market and have been available for decades, and in certain locations have experienced widespread adoption (even having achieved greater market share than non-condensing boilers in some areas). Given the track record of condensing boilers being installed and operated safely, DOE finds that installers are capable of safely installing and venting condensing boilers, even in circumstances that would require the venting system to be upgraded.

Additionally, in response to WMT, DOE expects that condensing boilers and non-condensing boilers alike would be capable of operating with return water temperatures of 180 °F. Thus, the return water temperature provided by the product would not be reason to differentiate product classes. DOE understands that condensing boilers, when operating at these temperatures,

would have minimal condensation occurring in the heat exchanger, which does result in non-condensing efficiency. This effect is accounted for in the energy use analysis (

see

section IV.E of this document).

b. Hydronic Heat Pump Boilers

In the May 2022 Preliminary Analysis, DOE specifically sought information regarding whether there are any performance-related features of heat pump boilers which would justify a separate product class. DOE also requested information on the expected market for such products (

see

the Executive Summary of the preliminary analysis TSD).

Rheem suggested that DOE should include heat pump boilers in the existing product class structure, but if that cannot be accomplished, a separate product class may be warranted, with changes to the regulatory definition for consumer boilers. (Rheem, No. 37 at p. 2)

Crown and U.S. Boiler stated that heat pump boilers are unable to generate water temperatures high enough to satisfy the design heating load of the vast majority of the residential hot water heating systems in the United States, and, therefore, if heat pump boilers are considered to be consumer boilers, they should be placed in their own products class. (Crown, No. 30 at p. 3; U.S. Boiler, No. 31 at p. 3) BWC commented that heat pump boilers are not able to provide the same utility as conventional consumer boilers, especially during extreme environmental conditions, and, therefore, should be placed in a separate class than conventional consumer boilers. (BWC, No. 39 at p. 1)

As discussed in section III.C of this document, the DOE test procedure for consumer boilers would not currently provide test results that are representative of the energy use or energy efficiency of an air-to-water or water-to-water heat pump boiler, and without an appropriate test procedure for these products at this time, DOE did not analyze heat pump boilers in this NOPR.

2. Market Assessment

In the market assessment, DOE obtains information on the present and past industry structure and market characteristics in order to inform multiple other analyses. In preparing the May 2022 Preliminary Analysis, DOE reviewed available public literature to develop an understanding of the consumer boiler industry in the United States, including assessing manufacturer market share and characteristics, existing regulatory and non-regulatory initiatives for improving product efficiency, and trends in product characteristics and retail markets. The Department used data sources such as its own Compliance Certification Database (CCD),

supplemented by information in California Energy Commission's Modernized Appliance Efficiency Database System (MAEDbS),

AHRI's Directory of Certified Product Performance,

and the U.S. Environmental Protection Agency's ENERGY STAR product finder.

DOE specifically sought comment in the May 2022 Preliminary Analysis on whether manufacturer model counts from publicly-available databases accurately reflect manufacturer market shares on a model-weighted or sales-weighted basis in order to inform the LCC analysis by providing insights into the typical consumer or installation scenarios (

see

the Executive Summary of the consumer boilers preliminary TSD).

DOE's CCD can be found online at:

www.regulations.doe.gov/certification-data/#q=Product_Group_s%3A*

(Last accessed Jan. 3, 2023).

MAEDbS can be found online at:

cacertappliances.energy.ca.gov/Pages/ApplianceSearch.aspx

(Last accessed Jan. 3, 2023).

AHRI's Directory of Certified Product Performance can be found online at:

www.ahridirectory.org/Search/SearchHome?ReturnUrl=%2f

(Last accessed March 1, 2023).

EPA's ENERGY STAR product finder can be found online at:

www.energystar.gov/products/products_list

(Last accessed Jan. 3, 2023).

WMT stated that certification databases do not indicate shipments and, thus, reflect the distribution of neither input capacities nor efficiencies. (WMT, No. 32 at pp. 7-8) WMT commented that the boilers market is increasingly transitioning towards higher efficiencies, and this is occurring in specific areas and regions where higher-efficiency consumer boilers have the most financial benefit and the application allows for it. The commenter stated that areas with lower adoption rates are based less on need for financial benefit than the inability to adapt the building to lower water circulation temperatures required for high-efficiency products; in other words, regions where local building codes or policies result in increased installation costs or even prohibit condensing appliance installations have the least transition towards higher efficiencies. WMT commented that this would disproportionally affect certain consumer subgroups. (WMT, No. 32 at p. 11)

Similarly, Rheem did not recommend using model counts from publicly-available databases to reflect market shares. (Rheem, No. 37 at p. 2)

AHRI also disagreed with the Department's use of manufacturer model counts from publicly-available databases to reflect manufacturer market shares on a model-weighted or sales-weighted basis, claiming that these databases do not accurately represent market share and misrepresent the market. (AHRI, No. 40 at p. 3) In a follow-up submission, AHRI provided information to DOE containing a market share analysis for gas-fired hot water boilers. AHRI stated that its contractor survey, completed in July 2022, was conducted in conjunction with the Air Conditioning Contractors of America (ACCA) and the Plumbing, Heating, and Cooling Contractors Association (PHCC), and that it gathered feedback from over 140 experienced contractors. (AHRI, No. 42 at p. 1)

DOE notes that the data provided by AHRI contained insights into manufacturer shipments, installation types, consumer boiler lifetimes, and other parameters which DOE has incorporated, as applicable, into its market assessment and considered for the downstream analyses (

e.g.,

LCC and PBP, shipments).

3. Technology Options

In the preliminary market analysis and technology assessment, DOE identified 13 technology options that would be expected to improve the efficiency (in terms of the three regulated metrics: AFUE, P

W,SB

, and P

W,OFF

) of consumer boilers, as measured by the DOE test procedure:

Technology options to improve AFUE:

heat exchanger improvements, modulating operation, vent dampers, direct vent, pulse combustion, premix burners, burner derating, low-pressure air-atomized oil burners, delayed-action oil pump solenoid valves, and electronic ignition.

Technology option to improve P

W,SB

and P

W,OFF

control relays for models with brushless permanent magnet (BPM) motors, transformer improvements, and switching mode power supplies.

Additionally, based on an extensive review of publicly available literature, DOE listed technologies that could potentially improve the overall efficiency of consumer boilers but would not result in improvements to AFUE, P

W,SB

, or P

W,OFF

. These were, namely: micro combined heat and power systems, improved motor efficiency, positive shut-off valves for oil burner nozzles, renewable natural

gas,

and heat pump technology. See chapter 3 of the preliminary TSD for details. After developing the preliminary list of technology options, DOE requested feedback on this list. The Department also sought information regarding the adoption of low-loss transformers and switching mode power supplies in consumer boilers to meet the existing P

W,SB

and P

W,OFF

standards.

Renewable natural gas is methane (natural gas) that is produced via the breakdown of biological material, then treated to remove contaminants.

BWC disagreed with some of the design characteristics which were presented in Table 3.3.2 of the preliminary TSD, stating that non-condensing copper heat exchangers can be either Category I or II venting, not just Category II venting. BWC also stated that condensing operation can begin in venting at around the 85-percent AFUE level, as opposed to the 88-percent AFUE threshold described in the preliminary TSD. BWC recommended that DOE perform a more up-to-date teardown analysis to address these discrepancies. (BWC, No. 39 at p. 2) In response, DOE believes that BWC may have misinterpreted the information provided in this table. Table 3.3.2 of the preliminary TSD simply provides brief descriptions of the terms that are used to characterize consumer boiler designs, and these terms are grouped together in accordance with the corresponding design parameter. DOE stated in Table 3.3.2 that copper heat exchangers are used in some non-condensing models, not that these heat exchangers are limited to Category II venting.

Rheem stated that renewable natural gas likely has little effect on efficiency compared to traditional natural gas, and, therefore, the commenter recommended that this technology option should be removed from the analysis. (Rheem, No. 37 at p. 2) DOE agrees that renewable natural gas would not result in improvements to AFUE, P

W,SB

, or P

W,OFF

, and, thus, this fuel has not been considered as a technology option in this NOPR.

AHRI stated that it does not have data on any current technologies that can be used to reach a more-stringent standard, but further stated that consumer boilers are typically installed within the thermal envelope of the building and any energy lost from the consumer boiler results in useful heat provided to the building. (AHRI, No. 40 at pp. 3-4) In response, DOE notes that a consumer boiler's primary purpose is to deliver heat to the hot water or steam in the home heating loop. DOE understands the comment from AHRI to mean that any technologies which limit the loss of heat from the consumer boiler to its immediate surroundings (

i.e.,

heat that does not go into the hot water or steam) should not be considered as improving the efficiency of the consumer boiler because the heat is ultimately delivered to the building even if it is not through the hot water or steam. The previous appendix N test procedure and the new appendix EE test procedure both account for this by assigning a value of 0 to the jacket loss factor (a value which quantifies heat lost directly to the consumer boiler's surroundings through its jacket) if the boiler is non-weatherized, as it is assumed to be located within the conditioned space of the building.

At the time of this analysis, DOE did not identify any commercially available weatherized consumer boilers. The technology options identified as improving AFUE are consistent with this understanding.

In defining the AFUE metric, EPCA states that this descriptor is based on the assumption that all weatherized warm air furnaces or boilers are located out-of-doors, and boilers which are not weatherized are located within the heated space. (42 U.S.C. 6291(20)(A)-(C)) The jacket loss is, therefore, assigned a value of 0 for any boilers that are non-weatherized.

DOE requests information on the market share of weatherized consumer boilers and the typical jacket losses of such products.

BWC strongly discouraged DOE from evaluating more-stringent standby mode and off mode power consumption (P

W,SB

and P

W,OFF

) standards. BWC commented that, based on its own testing, it has not seen a significant decrease in energy used in standby mode through the use of larger, low-loss transformers. BWC also stated that DOE's methodology of examining a few discrete components and their energy consumption instead of the overall power consumption of the consumer boiler was of concern to BWC because it fails to account for the power consumed by a consumer boiler's entire electrical system (including all ancillary components), and it recommended not to pursue more-stringent power consumption standards. (BWC, No. 39 at p. 2)

In response, DOE has considered this information about the implementation of low-loss transformers and has tentatively determined that it remains uncertain whether this technology option can be used to further reduce standby mode and off mode energy consumption. In the January 2016 Final Rule, DOE had determined that low-loss transformers and switching mode power supplies would be necessary to achieve the P

W,SB

and P

W,OFF

standards that were promulgated in that rule (which were set at the maximum technologically feasible levels at the time). 81 FR 2320, 2407-2408 (Jan. 15, 2016). As discussed in chapter 5 of the NOPR TSD, transformer improvements (

i.e.,

low loss transformers) and switching mode power supplies would have uncertain potential to further improve standby mode and off mode power consumption because these were considered to be the maximum technologically feasible designs in the January 2016 Final Rule which established the current standards. Thus, low-loss transformers and switching mode power supplies were not considered as potential design options for consumer boilers in this NOPR. In this NOPR, DOE tentatively determined that control relays are the only viable technology option remaining which can lead to discernible improvements to P

W,SB

and P

W,OFF

. However, as discussed in section IV.B of this document, control relays were screened out from further consideration, leaving no design options currently identified to improve these metrics. As a result, this NOPR did not further assess potential amended P

W,SB

and P

W,OFF

standards, and only amended AFUE standards are proposed. See chapters 3 and 4 of the NOPR TSD for further details of the technology assessment leading to this tentative conclusion not to further analyze amended standby mode and off mode energy consumption standards at this time.

DOE received multiple comments in response to the May 2022 Preliminary Analysis regarding heat pumps as technology options for consumer boilers. NYSERDA, the Joint Advocates, and NEEA recommended that heat pumps be considered as technology options once a test procedure for these products is established, suggesting that heat pump boilers would define the maximum technologically feasible efficiency for consumer boilers. (NYSERDA, No. 33 at p. 2; Joint Advocates, No. 35 at pp. 1-2; NEEA, No. 36 at pp. 1-2)

Additionally, NYSERDA stated that New York's ambitious climate objectives will require retrofitting the heating systems of existing homes to reduce GHGs, and given the prevalence of hydronic systems in the New York market, providing consumers choices for low-emission hydronic heating solutions will be important. (NYSERDA, No. 33 at p. 2)

The Joint Advocates commented that hydronic heating is used in 8 percent of homes overall in the United States, including 28 percent of homes in the Northeastern region, and heat pump boilers will assist that proportion's rise to higher efficiencies as State policies

shift forward. The Joint Advocates stated that gas absorption heat pumps can replace standard gas space heating appliances in cold climates, operating at much higher theoretical AFUE values. (Joint Advocates, No. 35 at pp. 1-2)

NEEA recommended that DOE should evaluate electric and gas heat pump technology, as well as dual-fuel heat pump boilers and gas absorption heat pump boilers, for consumer boilers as potential “max-tech” efficiency levels. NEEA stated that these products provide the same product utility as conventional consumer boilers and that these products are commercially available. (NEEA, No. 36 at pp. 1-2)

WMT, on the other hand, stated that it is not aware of viable heat pump boilers in the market which can operate consistently and reliably at circulating water temperatures sufficient for heating needs across the Nation. (WMT, No. 32 at p. 8) AHRI commented that it did not have data regarding current technologies that can be used to meet more-stringent standards or the adoption of electric heat pump or gas heat pump technology in the consumer boiler market. (AHRI, No. 40 at pp. 3-4)

As discussed in section IV.A.1.b of this document, DOE has tentatively determined that heat pump technology would not yield improvements in AFUE per the new appendix EE test procedure, and that further development of the test procedure would be necessary in order to address these novel products. Therefore, DOE has not included heat pump technologies in its list of technology options for this NOPR. The Department appreciates the feedback and information provided by stakeholders on this topic and will continue to evaluate heat pump boilers in a future rulemaking.

B. Screening Analysis

DOE uses the following five screening criteria to determine which technology options are suitable for further consideration in an energy conservation standards rulemaking:

(1)

Technological feasibility.

Technologies that are not incorporated in commercial products or in commercially viable, existing prototypes will not be considered further.

(2)

Practicability to manufacture, install, and service.

If it is determined that mass production of a technology in commercial products and reliable installation and servicing of the technology could not be achieved on the scale necessary to serve the relevant market at the time of the projected compliance date of the standard, then that technology will not be considered further.

(3)

Impacts on product utility.

If a technology is determined to have a significant adverse impact on the utility of the product to subgroups of consumers, or results in the unavailability of any covered product type with performance characteristics (including reliability), features, sizes, capacities, and volumes that are substantially the same as products generally available in the United States at the time, it will not be considered further.

(4)

Safety of technologies.

If it is determined that a technology would have significant adverse impacts on health or safety, it will not be considered further.

(5)

Unique-pathway proprietary technologies.

If a technology has proprietary protection and represents a unique pathway to achieving a given efficiency level, it will not be considered further, due to the potential for monopolistic concerns.

10 CFR part 430, subpart C, appendix A, sections 6(b)(3) and 7(b).

In summary, if DOE determines that a technology, or a combination of technologies, fails to meet one or more of the listed five criteria, it will be excluded from further consideration in the engineering analysis. The reasons for eliminating any technology are discussed in the following sections.

The subsequent discussion includes comments from interested parties pertinent to the screening criteria, DOE's evaluation of each technology option against the screening analysis criteria, and whether DOE determined that a technology option should be excluded (“screened out”) based on the screening criteria.

In response to the May 2022 Preliminary Analysis, several commenters raised concerns regarding the consideration of an 85-percent AFUE efficiency level for gas-fired hot water boilers, stating that this particular efficiency could have issues with installation and repair, reliability, and safety. These commenters assert that this issue should have bearing on DOE's consideration of technology options for this rulemaking.

AGA, APGA, and NPGA stated that if DOE were to propose 85-percent AFUE as a standard, it would be too close to condensing operation to be safely implemented with existing Category I venting systems, and that forcing the consumer to upgrade to condensing technology would place undue burden and expense on the consumer. AGA, APGA, and NPGA stated that manufacturers would not produce consumer boilers that are prone to failure, instead opting to make condensing boilers, thereby limiting the choice of and increasing the burden on the consumer. (AGA, APGA and NPGA, No. 38 at p. 3) Rheem similarly expressed concern that the 85-percent efficiency level is too close to condensing operation to be used safely without reliability issues and costly upgrades. (Rheem, No. 37 at p. 4)

Reiterating its comments from the previous standards rulemaking, Crown provided data from the U.S. Consumer Product Safety Commission (CPSC) on failure modes that led or contributed to carbon monoxide incidents associated with modern furnaces and boilers between the years 2002-2009 and concluded that, as the AFUE increases, the likelihood that one of these failure modes would cause a carbon monoxide incident also increases. Crown stated that this is due the flue gases being less buoyant at higher efficiencies, and, thus, being less able to overcome the effects of depressurization, partial blockage, back-drafting, or an improperly designed vent system; additionally, cooler flue gases are more likely to cause damage to the vent system if something else also goes wrong (

e.g.,

Crown provided the example of trace halogen aspiration into the consumer boiler). (Crown, No. 30 at pp. 3-5) U.S. Boiler provided the same comments as Crown. (U.S. Boiler, No. 31 at pp. 3-5)

Crown stated that setting a standard for gas-fired hot water boilers at 85-percent AFUE would completely ignore the safety and reliability concerns that can result from the installation of a consumer boiler operating at this efficiency level into a Category I chimney. Crown provided graphical data charting flue gas CO

concentration and net flue gas temperature that suggested that the steady-state efficiency at which a consumer boiler could operate while maintaining a Category I designation would be between 82.7-84.1-percent AFUE. Crown made the observation that, since AFUE will never exceed steady-state efficiency, the current standard at 84-percent AFUE, for all practical purposes, is already at this limit. Crown argued that while there are consumer boilers on the market at 85-percent AFUE, not all of them are certified to ANSI Z21.13, “Gas-Fired Low Pressure Steam And Hot Water Boilers,” and are, therefore, not officially Category I venting. Crown also stated that these 85-percent AFUE consumer boilers have modifications such as power gas burners and operate in conditions different than laboratory conditions where AFUE was determined, creating uncertainty on whether they would be safe in all field conditions. Crown commented that while there are explicit instructions on how to install consumer boilers, manufacturers have little control on whether these instructions are followed, and an AFUE minimum of 85 percent introduces more of a safety risk to the consumer; therefore, a standard at this level would force all manufacturers to

either prescribe vent requirements more stringent than those currently in the National Fuel Gas Code and/or give up any remaining extra safety margin they have built into their products for suboptimal vent systems, all for an incremental energy savings benefit likely amounting to a rounding error. (Crown, No. 30 at pp. 3-5) U.S. Boiler provided the same comments. (U.S. Boiler, No. 31 at pp. 3-5)

In response, DOE understands that Crown, U.S. Boiler, APA, APGA, and NPGA are concerned about the safety of installing gas-fired hot water boilers with incremental heat exchanger improvements (leading to an AFUE of 85 percent) within current Category I venting systems. However, as a technology option, an increase in heat exchanger effectiveness alone does not pose a safety risk for consumers or service technicians. To this point, in the January 2016 Final Rule, the Department recognized that certain efficiency levels could pose health or safety concerns under certain conditions if they are not installed properly in accordance with manufacturer specifications. However, these concerns can be resolved with proper product installations and venting system design; this is evidenced by the significant shipments of products that are currently commercially available at these efficiency levels, as well as the lack of restrictions on the installation location of these units in installation manuals. In addition, DOE noted that products achieving these efficiency levels have been on the market since at least 2002, which demonstrates their reliability, safety, and consumer acceptance. In some circumstances, if the potential for condensate is high, different vent materials (such as a high grade stainless steel vent) may be required to withstand the condensate. High efficiency condensing boilers typically use PVC/CPVC venting since the exhaust gases are cool enough. Given the significant product availability and the amount of time products at these efficiency levels have been available on the market, DOE continues to believe that products at these efficiency levels are safe and reliable when installed correctly. 81 FR 2320, 2344-2345 (Jan. 15, 2016).

Further, DOE examined the most recent report from the CPSC regarding carbon monoxide incidents related to the use of consumer products, which presented data from 2018 (CPSC 2018 Report).

This report discusses that information collected on the carbon monoxide incidents often describes conditions of compromised vent systems, flue passageways, and chimneys for furnaces, boilers, and other heating systems. CPSC 2018 Report at p. 9. Specifically, the CPSC 2018 Report states that “[a]ccording to the information available, some products had vents that became detached or were installed/maintained improperly. Vents were also sometimes blocked by soot caused by inefficient combustion, which, in turn, may have been caused by several factors, such as leaky or clogged burners, an over-firing condition, or inadequate combustion air. Other furnace-related conditions included compromised heat exchangers or filter doors/covers that were removed or not sealed. Some products were old and apparently not well maintained. Other incidents mentioned a backdraft condition, large amounts of debris in the chimney, and the use of a product that was later prohibited by the utility company and designated not to be turned on until repaired.”

Id.

Based on this information, DOE has tentatively determined that it is the potential for older or improperly maintained venting and burner systems to be inadequate which may pose a safety risk, and not the higher-efficiency consumer boiler itself. In other words, high efficiency boilers available on the market today are just as safe as baseline boilers when they are installed and maintained properly. If either high-efficiency or low-efficiency boilers are not installed and maintained properly, then some potential for safety concerns may exist as outlined by the CPSC report. But DOE has not found, nor have commenters presented, evidence that more stringent standards for boilers would result in a reduction of boiler safety. In the LCC analysis, DOE accounts for the costs associated with correctly installing boilers (including modifications to vent system when appropriate), as well as preventative maintenance and any necessary repairs over the lifetime of a product. As a result, DOE has not screened out heat exchanger improvements as a technology option from this NOPR analysis.

M.V. Hnatov, “Non-Fire Carbon Monoxide Deaths Associated with the Use of Consumer Products; 2018 Annual Estimates,” U.S. Consumer Product Safety Commission, September 2021. Available online at

www.cpsc.gov/s3fs-public/Non-Fire-Carbon-Monoxide-Deaths-Associated-with-the-Use-of-Consumer-Products-2018-Annual-Estimates.pdf?VersionId=IN1CTo8Njoxta0CmddOUl2t.tmQ.iEEb

(Last accessed Jan. 3, 2023).

PB Heat stated that the current minimum efficiency levels are close to the condensing range, and increasing them any further will reduce applications where Category I consumer boilers can be installed and, therefore, reduce consumer utility and access to affordable heating. (PB Heating, No. 34 at p. 1)

As stated in section IV.A.1.a of this document, in this rulemaking, DOE is not considering venting configurations to constitute a consumer or product utility, consistent with the conclusions of the December 2021 Interpretive Rule. DOE acknowledges that certain types of homes may require substantial investment to upgrade the venting if transitioning from a Category I vent system to a Category IV vent system, and the Department aims to accurately capture these costs to the consumer in the LCC and PBP analyses. Additionally, DOE has considered a low-income consumer subgroup in order to assess the LCC impacts on access to affordable heating in particular. The details of these analyses are discussed in sections IV.F and IV.I of this document, respectively.

1. Screened-Out Technologies

Rheem suggested that hydrogen technology (including hydrogen and hydrogen blends) should be screened out from the technology options in this rulemaking due to technological feasibility. (Rheem, No. 37 at p. 3)

In response, DOE notes that in commenting on the March 2021 RFI, Rheem had recommended that the Department consider new fuel sources, including hydrogen-blended gas and renewable natural gas, while stating that industry groups are currently evaluating the safe and efficient use of hydrogen-blended fuels (with up to 15-percent hydrogen) in gas-fired appliances. (Rheem, No. 10 at p. 5) Consequently, DOE included hydrogen-ready boilers

in the technology assessment of the May 2022 Preliminary Analysis (

see

chapter 3 of the preliminary TSD). DOE evaluated hydrogen-ready boilers and differences in burner systems that would be able to accommodate a transition to hydrogen blend gas and has tentatively determined that hydrogen-ready burner designs do not appear to contribute to gains in AFUE. As a result of these findings, DOE did not consider hydrogen-ready burners in this NOPR as a technology option to improve consumer boiler AFUE, and, thus, this technology was not even included in the NOPR screening analysis. In addition, DOE notes that hydrogen-ready boilers do not appear to be commercially-available technologies in the United States, and have not yet been

demonstrated to be commercially-viable and mass-produced, as per screening criteria number 2; therefore, even if hydrogen-ready burners were to provide an efficiency benefit to consumer boilers, this technology would have likely been screened out during this proposed rulemaking on the basis of practicability to manufacture, install, and service.

“Hydrogen-ready” boilers are appliances that have the ability to burn both natural gas and hydrogen (

i.e.,

either a blend of the two fuels or a complete switch between fuels).

DOE requests further information on the potential future adoption of hydrogen-ready consumer boilers in the United States and any data demonstrating potential impacts of these burner systems on AFUE.

After consideration of each technology option analyzed in the technology assessment, DOE has screened out the following technologies in this NOPR analysis: condensing operation in oil-fired hot water boilers, pulse combustion, burner derating, low-pressure air-atomized oil burners, and control relays for models with BPM motors. DOE screened these technologies out in the May 2022 Preliminary Analysis for the reasons explained in that document (

see

chapter 4 of the preliminary analysis TSD), but the Department did not receive any additional feedback from stakeholders on these determinations. Table IV.2 presents the criteria that were the basis for screening out each of these technologies from further consideration in the NOPR analysis. Further details can be found in chapter 4 of the NOPR TSD.

Table IV.2—Screened-Out Technologies for Consumer Boilers

Technology option

EPCA criterion (X = basis for screening out)

Technological feasibility

Practicability to manufacture,

install, and

service

Adverse

impacts on

utility or

availability

Adverse

impacts on health and safety

Unique-

pathway

proprietary

technologies

Condensing operation in oil-fired hot water boilers

Pulse combustion

Burner derating

Low-pressure air-atomized oil burners

Control relays for BPM motors

DOE requests comment on the tentative determination that condensing operation in oil-fired hot water boilers, pulse combustion, burner derating, low-pressure air-atomized oil burners, and control relays for models with BPM motors should be screened out from further analysis.

2. Remaining Technologies

Through a review of each technology, DOE tentatively concludes that all of the other identified technologies met all five screening criteria to be examined further as design options to improve AFUE in DOE's NOPR analysis. In summary, DOE did not screen out the following technology options presented in Table IV.3.

Table IV.3—Retained Technologies for Consumer Boilers

Technology

Type

Design Option

Fans/Venting

Inducer fans.*

Vent dampers.

Direct venting/power venting.

Heat Exchanger Improvements

Condensing heat exchanger (for gas hot water boilers only)

Improved geometry and increased heat exchanger surface area.

Baffles.

Burner

Modulating operation/modulating Aquastats.

Premix burners.

Delayed-action oil pump solenoid valves.

Ignition

Electronic ignition (for oil-fired boilers)

* In chapter 3 of the May 2022 Preliminary Analysis TSD, inducer fans were described as mechanical draft systems and grouped with heat exchanger improvements, as use of induced draft can allow for use of more restrictive heat exchanger designs that improve heat transfer.

DOE has initially determined that these technology options are technologically feasible because they are being used or have previously been used in commercially-available products or working prototypes. DOE also finds that all of the remaining technology options to improve AFUE meet the other screening criteria (

i.e.,

practicable to manufacture, install, and service and do not result in adverse impacts on consumer utility, product availability, health, or safety, unique-pathway proprietary technologies).

By screening out control relays for models with BPM motors, DOE has tentatively determined that there remain no other technology options which could viably improve standby mode and off mode power consumption. As a result of this screening analysis, DOE has tentatively determined that it is not technologically feasible at this time to increase the stringency of the standby mode and off mode power consumption standards for consumer boilers.

For additional details, see chapter 4 of the NOPR TSD.

C. Engineering Analysis

The purpose of the engineering analysis is to establish the relationship between the efficiency and cost of consumer boilers. There are two elements to consider in the engineering analysis: the selection of efficiency levels to analyze (

i.e.,

the “efficiency analysis”) and the determination of product cost at each efficiency level (

i.e.,

the “cost analysis”). In determining the performance of higher-efficiency products, DOE considers technologies

and design option combinations not eliminated by the screening analysis. For each product class, DOE estimates the baseline cost, as well as the incremental cost for the product at efficiency levels above the baseline. The output of the engineering analysis is a set of cost-efficiency “curves” that are used in downstream analyses (

i.e.,

the LCC and PBP analyses and the NIA).

As discussed in the previous section of this document, DOE has tentatively determined that it is not technologically feasible at this time to increase the stringency of the standby mode and off mode power consumption standards for consumer boilers because all of the potential technology options have either uncertain impact on P

W,SB

and P

W,OFF

or have been removed from further consideration in the screening analysis. Thus, the engineering analysis of this NOPR assesses improvements in AFUE only.

AHRI supported the Department's preliminary decision not to analyze a more-stringent standard for standby and off mode power consumption, stating that there is limited benefit to setting a more-stringent standard. (AHRI, No. 40 at p. 4) Rheem also supported DOE's tentative determination not to analyze more-stringent standby mode and off mode standards. Rheem requested clarification as to whether DOE can simultaneously increase the minimum AFUE if that results in an increase in electrical energy consumption and a corresponding increase in standby mode and off mode energy use, even if the combined change results in a net decrease in energy use. (Rheem, No. 37 at pp. 3-4)

In response to the question from Rheem, EPCA states that the Secretary may not prescribe any amended standard which increases the maximum allowable energy use or decreases the minimum required energy efficiency of a covered product (which includes consumer boilers). (42 U.S.C. 6295(o)(1)) This statutory “anti-backsliding” provision would prohibit DOE from increasing the standby mode and off mode energy consumption standards.

The comment from Rheem appears to suggest that standards should consider a combined metric of both active mode, standby mode, and off mode energy consumption. EPCA requires integration of standby mode and off mode energy consumption “into the overall energy efficiency, energy consumption, or other energy descriptor for each covered product, with one exception being if such an integrated test procedure is technically infeasible for a particular covered product, in which case the Secretary shall 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)) In a final rule published in the

Federal Register

on October 20, 2010, DOE determined that an integrated metric is not technically feasible because the measurement of standby mode and off mode energy consumption is much smaller than the active mode fuel consumption reflected in AFUE, making the standby mode and off mode energy consumption infeasible to regulate as part of a combined metric. 75 FR 64621, 64622-64627.

From its own test data and manufacturer interviews, DOE has tentatively determined that increases to the AFUE of a boiler would not result in increases to the standby mode and off mode power consumption in such a way that it would be impossible to comply with the existing standby mode and off mode power consumption standards.

Additionally, as discussed in section III.C of this document, DOE's test method for consumer boilers assigns a value of 100-percent AFUE to any electric boiler which is non-weatherized (see section 11.1 of ASHRAE 103-2017, which is incorporated by reference into appendix EE). DOE has not identified any electric boilers that are weatherized or intended for installation outdoors, and has tentatively determined that electric boilers would typically be non-weatherized and installed indoors. As such, the AFUE for these products would already be at the maximum possible value per the test procedure. Thus, DOE did not further analyze electric hot water or electric steam boilers in the engineering analysis, and AFUE-based standards for these product classes are not proposed in this NOPR.

The following subsections outline the methodology used when conducting the efficiency analysis and cost analysis.

1. Efficiency Analysis

DOE typically uses one of two approaches to develop energy efficiency levels for the engineering analysis: (1) relying on observed efficiency levels in the market (

i.e.,

the efficiency-level approach), or (2) determining the incremental efficiency improvements associated with incorporating specific design options to a baseline model (

i.e.,

the design-option approach). Using the efficiency-level approach, the efficiency levels established for the analysis are determined based on the market distribution of existing products (in other words, based on the range of efficiencies and efficiency level “clusters” that already exist on the market). Using the design option approach, the efficiency levels established for the analysis are determined through detailed engineering calculations and/or computer simulations of the efficiency improvements from implementing specific design options that have been identified in the technology assessment. DOE may also rely on a combination of these two approaches. For example, the efficiency-level approach (based on actual products on the market) may be extended using the design option approach to “gap fill” levels (to bridge large gaps between other identified efficiency levels) and/or to extrapolate to the max-tech level (particularly in cases where the max-tech level exceeds the maximum efficiency level currently available on the market).

In this proposed rulemaking, DOE has relied on the efficiency-level approach. This approach ensures that the efficiency levels considered in the engineering analysis are attainable using technologies which are commercially available and viable for consumer boilers, and DOE considered this approach reasonable because all of the technology options to improve AFUE that passed the screening analysis have been observed in commercially-available products. Additionally, as discussed later, since the consumer boiler industry is relatively mature, it exhibits a design option pathway to improved AFUE efficiency demonstrated by models on the market. As such, DOE was able to conduct teardown analyses on consumer boilers which meet each efficiency level, and ascertain a list of representative design options which manufacturers are most likely to employ in order to achieve these efficiencies. The selection of these efficiency levels from market data is discussed in the following sections.

a. Baseline Efficiency

For each product class, DOE generally selects a baseline model as a reference point for each class, and measures changes resulting from potential energy conservation standards against the baseline. The baseline model in each product class represents the characteristics of a product typical of that class (

e.g.,

capacity, physical size). Generally, a baseline model is one that just meets current energy conservation standards, or, if no standards are in place, the baseline is typically the most common or least efficient unit on the market. For consumer boilers, there currently exist minimum AFUE standards for gas-fired and oil-fired products at 10 CFR 430.32(e)(2)(iii)(A), which were used to define the baseline efficiency levels for these product classes. Additionally, baseline models

must meet the design requirements at 10 CFR 430.32(e)(2)(iii)(A) and the standby mode and off mode power consumption standards at 10 CFR 430.32(e)(2)(iii)(B).

b. Higher Efficiency Levels

As part of DOE's analysis, the maximum available efficiency level is the highest efficiency unit currently available on the market. DOE also defines a “max-tech” efficiency level to represent the maximum possible efficiency for a given product. For this analysis, because the consumer boiler industry is relatively mature and there is a clear design option pathway to improved AFUE efficiency demonstrated by models on the market, DOE has tentatively determined that the maximum available efficiency level is representative of the max-tech efficiency level for gas-fired and oil-fired boilers, and that any additional design options that could theoretically be used to further improve efficiency have been screened out. The max-tech efficiency levels analyzed in the May 2022 Preliminary Analysis are provided in Table IV.4.

Table IV.4—Max-Tech AFUE Efficiency Levels for Consumer Boilers

Product class

AFUE

(%)

Gas-fired hot water

Gas-fired steam

Oil-fired hot water

Oil-fired steam

In the May 2022 Preliminary Analysis, DOE also considered the range of input capacities of models certified at these efficiencies to ensure that the max-tech efficiencies analyzed would not inadvertently correspond to a lessening of product availability to meet the full range of household heating needs (

see

chapter 5 of the preliminary analysis TSD). These assessments were made based on the database of consumer boilers constructed as part of the market assessment, discussed in section IV.A.2 of this document.

In response to the May 2022 Preliminary Analysis, AHRI noted that NFPA-31, “Standard for the Installation of Oil‐Burning Equipment” (NFPA-31),

provides guidance for the relining of chimneys based on steady-state efficiency, and within these guidelines are restrictions on higher-efficiency oil boilers that AHRI stated may have an impact on consumers. AHRI commented that, according to NFPA-31, a 6-inch diameter by 35-foot long metal chimney liner can be used for an 86-percent “steady-state efficiency” boiler having an input between 119,000 and 280,000 Btu/h, but this input range becomes 140,000 to 210,000 Btu/h if the “steady-state efficiency” is 88-percent. As a result, AHRI recommended that DOE should treat 86.0-percent AFUE as max-tech for oil-fired hot water boilers. (AHRI, No. 40 at p. 4)

NFPA-31 Appendix E states that metal chimney liners may be needed to reduce transient low draft during startup, as well as protect masonry from acidic condensate damage. The required size of the liner is specified based on the steady state efficiency of the boiler, which is shown in NFPA-31 Appendix E tables E.5.4(a) and E.5.4(b).

In response, DOE reviewed the 2020 edition of NFPA-31

and notes that Tables E.5.4(a) through E.5.4(e) of that standard present the chimney metal liner specifications that are appropriate for various firing rates (in terms of gallons of oil per hour), and DOE understands that AHRI has converted these values of oil firing rates into Btu/h input rates. AHRI's comment indicates that, for a 6-inch diameter by 35-foot long chimney liner, a steady-state efficiency

greater than 86-percent could result in a smaller range of input capacities allowable. Upon further inspection of Table E.5.4(a) of NFPA-31, DOE notes that AHRI's calculation is based on a lateral run of 10 feet. Adjusting to a shorter horizontal vent run of 4 feet,

for example, would allow households to meet their heating needs using a boiler with a higher efficiency. Table E.5.4(a) of NFPA-31 indicates that a firing rate of 1.75 gallons per hour (approximately 245,000 Btu/h) is acceptable at the high end of firing rates for steady-state efficiencies of 88 percent, which DOE estimates would correspond to AFUEs of 87-88 percent. This would suggest that the narrowing of the acceptable input capacity range is not significant enough to mean that a large fraction of homes would not be able to find a replacement boiler to meet their heating needs if the standard were set at 88-percent AFUE.

Found online at

link.nfpa.org/free-access/publications/31/2020

(Last accessed Jan. 3, 2023).

Section E.8.3 of NFPA-31 suggests that the steady-state efficiency of a hydronic boiler can be estimated by adding 1 percentage point to the rated AFUE of the boiler.

As discussed in appendix 8D of the NOPR TSD, most oil-fired boilers do not have a horizontal vent option, so the horizontal run would be limited for vertical venting.

Therefore, upon re-evaluating the input capacity ranges available for the maximum available AFUEs on the market, DOE has initially concluded that the max-tech levels from the May 2022 Preliminary Analysis are still applicable, and these levels were analyzed as max-tech in this NOPR.

Between the baseline efficiency level and max-tech efficiency level, DOE analyzed several other intermediate higher efficiency levels. In the May 2022 Preliminary Analysis, DOE sought comment on whether the AFUE efficiency levels identified at the preliminary stage were appropriate for each product class (see the Executive Summary of the preliminary TSD).

As discussed in section IV.B of this document, DOE received multiple comments regarding the 85-percent AFUE efficiency level which was analyzed for gas-fired hot water boilers in the May 2022 Preliminary Analysis. For the reasons explained in that section, the Department has tentatively determined that the concerns raised by stakeholders reflect potential downsides to these products regarding the installation, maintenance, and repair costs—and not a risk directly associated with incrementally more-efficient heat exchanger technologies. Hence, DOE has retained the 85-percent AFUE efficiency level in this NOPR analysis after observing that a substantial number of models on the market are certified at this level. This observation is further corroborated by AHRI's 2021 shipment data for consumer boilers, which indicate that boilers rated between 85.0-percent and 85.9-percent AFUE are the second-highest frequency of non-condensing model shipments, behind only baseline models (see AHRI, No. 42 at p. 2).

Crown provided a detailed analysis of how venting category requirements correlate to the flue gas temperature and percent of CO

in the flue gas, and described the approximate relationship between these parameters and the steady-state co

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