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EO12866_NSPSResidentialWoodHeaters_2060-AP93_NPRM_20130619.docx 

6560-50-P

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 60

[EPA-HQ-OAR-2009-0734; FRL- ]

RIN 2060-AP93 

Standards of Performance for New Residential Wood Heaters, New Residential

Hydronic Heaters and Forced-Air Furnaces, and New Residential Masonry Heaters

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

SUMMARY: The EPA is proposing to amend the Standards of Performance for New 

Residential Wood Heaters and to add two new subparts: Standards of Performance for 

New Residential Hydronic Heaters and Forced-Air Furnaces and Standards of 

Performance for New Residential Masonry Heaters. This proposal is aimed at achieving

several objectives for new residential wood heaters and other wood-burning appliances,

including applying updated emission limits that reflect the current best systems of 

emission reduction; eliminating exemptions over a broad suite of residential wood 

combustion devices; strengthening test methods as appropriate; and streamlining the 

certification process. This proposal does not include any requirements for heaters solely 

fired by gas, oil or coal. In addition, it does not include any requirements associated with

wood heaters or other wood-burning appliances that are already in use.

Particulate pollution from wood heaters is a significant national air pollution 

problem and human health issue. Health benefits associated with these proposed 

regulations are valued to be over 200 times greater than the cost to manufacture cleaner, 
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lower emitting appliances. These proposed regulations would also significantly reduce 

emissions of many other pollutants from these appliances, including carbon monoxide, 

volatile organic compounds, hazardous air pollutants and greenhouse gases.

DATES: Comments must be received on or before [INSERT DATE 90 DAYS AFTER 

PUBLICATION IN THE FEDERAL REGISTER]. Under the Paperwork Reduction 

Act, comments on the information collection provisions are best assured of having full 

effect if the Office of Management and Budget (OMB) receives a copy of your comments 

on or before [INSERT DATE 30 DAYS AFTER DATE OF PUBLICATION IN THE 

FEDERAL REGISTER].

Public Hearing. The EPA will hold a public hearing on this proposed rule if 

requested. Requests for a hearing must be made by [INSERT DATE 10 DAYS AFTER 

DATE OF PUBLICATION IN THE FEDERAL REGISTER]. Contact Mr. David 

Cole via email at cole.david@epa.gov or by phone at (919) 541-5565 to request a public 

hearing. If a hearing is requested, the EPA will announce the details, including specific 

dates, times, addresses and contact information for the hearing in a separate Federal 

Register notice. Note that there is no extra weight placed on the comments presented at a 

public hearing versus comments submitted via the process discussed in the 

“ADDRESSES” section below. Potential speakers should still submit a written copy of 

their comments to best ensure that they have full effect. Also, note that the EPA does not 

normally make a presentation at the hearings and only asks clarifying questions. If you 

are interested in attending a public hearing, contact Mr. David Cole (see above for 

contact information) to verify whether a hearing will be held.
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ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-OAR2009-0734, by one of the following methods: 

 www.regulations.gov: Follow the on-line instructions for submitting comments.

 Email: a-and-r-docket@epa.gov, Attention Docket ID No. EPA-HQ-OAR-2009-

0734. 

 Fax: (202) 566-9744, Attention Docket ID No. EPA-HQ-OAR-2009-0734. 

 Mail: United States (U.S.) Postal Service, send comments to EPA Docket Center, 

EPA West (Air Docket), Attention Docket ID Number EPA-HQ-OAR-2009-0734, 

U.S. Environmental Protection Agency, Mailcode: 2822T, 1200 Pennsylvania Ave., 

NW, Washington, DC 20004. Please include a total of two copies. In addition, please 

mail a copy of your comments on the information collection provisions to the Office 

of Information and Regulatory Affairs, Office of Management and Budget (OMB), 

Attn: Desk Officer for EPA, 735 17th St., NW, Washington, DC 20503.

 Hand Delivery: EPA Docket Center, EPA West (Air Docket), Room 3334, 1301 

Constitution Avenue, NW, Washington, DC, Attention Docket ID Number EPA-HQOAR-2009-0734. Such deliveries are only accepted during the Docket’s normal hours 

of operation, and special arrangements should be made for deliveries of boxed 

information.

Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-2009-0734. 

The EPA's policy is that all comments received will be included in the public docket 

without change and may be made available online at www.regulations.gov, including any

personal information provided, unless the comment includes information claimed to be 

Confidential Business Information (CBI) or other information whose disclosure is 
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restricted by statute. Do not submit information that you consider to be CBI, or otherwise 

protected, through www.regulations.gov or email. The www.regulations.gov website is 

an “anonymous access” system, which means the EPA will not know your identity or 

contact information unless you provide it in the body of your comment. If you send an 

email comment directly to the EPA without going through www.regulations.gov, your 

email address will be automatically captured and included as part of the comment that is 

placed in the public docket and made available on the Internet. If you submit an 

electronic comment, the EPA recommends that you include your name and other contact 

information in the body of your comment and with any disk or CD-ROM you submit. If 

the EPA cannot read your comment due to technical difficulties and cannot contact you 

for clarification, the EPA may not be able to consider your comment. Electronic files 

should avoid the use of special characters, any form of encryption, and be free of any 

defects or viruses. For additional information about the EPA’s public docket, visit the 

EPA Docket Center homepage at www.epa.gov/epahome/dockets.htm. For additional 

instructions on submitting comments, go to section I.D.2 of the SUPPLEMENTARY 

INFORMATION section of this document.

Docket: The EPA has established a docket for this rulemaking under Docket ID 

Number EPA-HQ-OAR-2009-0734. All documents in the docket are listed in the 

www.regulations.gov index. Although listed in the index, some information is not 

publicly available, e.g., CBI or other information whose disclosure is restricted by statute. 

Certain other material, such as copyrighted material, will be publicly available only in 

hard copy form. Publicly available docket materials are available either electronically in 

www.regulations.gov or in hard copy at the EPA Docket Center, EPA West, Room 3334, 
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1301 Constitution Ave., NW, Washington, DC. The Public Reading Room is open from 

8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The telephone 

number for the Public Reading Room is (202) 566-1744, and the telephone number for 

the Air Docket is (202) 566-1742.

Public Hearing. If a public hearing is held, it will be announced in a separate 

Federal Register notice that provides details, including specific dates, times, addresses 

and contact information for the hearing.

FOR FURTHER INFORMATION CONTACT: For questions about this proposed 

action, contact Mr. Gil Wood, Office of Air Quality Planning and Standards, Outreach 

and Information Division, Community and Tribal Programs Group (C304-03), U.S. 

Environmental Protection Agency, Research Triangle Park, North Carolina 27711; 

telephone number: (919) 541-5272; fax number: (919) 541-0242; email address: 

wood.gil@epa.gov. 

SUPPLEMENTARY INFORMATION: The information in this preamble is organized 

as follows:

I. General Information

A. Executive Summary

B. Does this action apply to me?

C. Where can I get a copy of this document?

D. What should I consider as I prepare my comments for the EPA?

II. Background 

A. What is the NSPS program?

B. Why was the original residential wood heaters NSPS developed?

C. What are the requirements of the current 1988 NSPS?

D. What are the major developments since the original NSPS was published?

E. Why is residential wood smoke a concern?

F. What are the major issues that drove the review process?

III. Summary of Proposed Residential Wood Heater Appliance Amendments 

A. Room Heaters

B. Central Heaters: Hydronic Heaters and Forced-Air Furnaces

C. Masonry Heaters
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IV. Summary of Environmental, Cost, Economic, and Non-Air Health and Energy

Impacts 

A. What are the air quality impacts? 

B. What are the benefits?

C. What are the cost impacts? 

D. What are the economic impacts? 

E. What are the non-air quality health and energy impacts? 

V. Rationale for Proposed Amendments

A. Why are we proposing to expand the scope of appliances subject to the NSPS?

B. How did we determine BSER and the proposed emission standards?

C. How did we establish the proposed compliance timelines? 

D. How are we proposing to streamline the requirements for certification, quality

assurance and laboratory accreditation? 

E. What changes and additions to the allowed test methods are we proposing?

F. What other changes and additions to the administrative requirements are we 

proposing? 

VI. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive Order 

13563: Improving Regulation and Regulatory Review

B. Paperwork Reduction Act

C. Regulatory Flexibility Act

D. Unfunded Mandates Reform Act

E. Executive Order 13132: Federalism

F. Executive Order 13175: Consultation and Coordination with Indian Tribal 

Governments

G. Executive Order 13045: Protection of Children from Environmental Health Risks and 

Safety Risks

H. Executive Order 13211: Actions Concerning Regulations That Significantly Affect 

Energy Supply, Distribution, or Use

I. National Technology Transfer and Advancement Act

J. Executive Order 12898: Federal Actions to Address Environmental Justice in 

Minority Populations and Low-Income Populations

I. General Information

A. Executive Summary

1. Purpose of the Regulatory Action

The purpose of this action is to propose amendments to the Standards of 

Performance for New Residential Wood Heaters (40 CFR part 60, subpart AAA) and to 

add two new subparts: Standards of Performance for New Residential Hydronic Heaters 

and Forced-Air Furnaces and Standards of Performance for New Residential Masonry
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Heaters (40 CFR part 60, subparts QQQQ and RRRR). This proposal was developed 

following a Clean Air Act (CAA) section 111(b)(1)(B) periodic review of the current

residential wood heater new source performance standards (NSPS). We concur with 

numerous stakeholders that the current body of evidence justifies revision of the current 

residential wood heaters NSPS to capture the improvements in performance of such units 

and to expand the applicability of this NSPS to include additional wood-burning 

residential heating devices that are in the market. The proposed changes are aimed at 

achieving several objectives, including applying updated emission limits that reflect the 

current best systems of emission reduction (BSER); eliminating exemptions over a broad 

suite of residential wood combustion devices; strengthening test methods as appropriate; 

and streamlining the certification process. 

These revisions will also reduce the health impacts of fine particle pollution, of

which wood smoke is a contributing factor in many areas. Residential wood smoke 

contains fine particles with an aerodynamic diameter of 2.5 micrometers or less (PM2.5), 

carbon monoxide (CO), toxic air pollutants (e.g., benzene and formaldehyde), and 

climate gases (e.g., methane and black carbon). Residential wood smoke can increase 

PM2.5 to levels that cause significant health concerns (e.g., asthma attacks, heart attacks, 

premature death). Populations that are at greater risk for experiencing health effects 

related to fine particle exposures include older adults, children and individuals with preexisting heart or lung disease. Each year, smoke from wood heaters contributes hundreds 

of thousands of tons of fine particles throughout the country – mostly during the winter 

months. Nationally, residential wood combustion accounts for 44 percent of total 

stationary and mobile polycyclic organic matter (POM) emissions, nearly 25 percent of 
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all area source air toxics cancer risks and 15 percent of noncancer respiratory effects.

1

Residential wood smoke causes many counties in the U.S. to either exceed the EPA’s 

health-based national ambient air quality standards (NAAQS) for fine particles or places 

them on the cusp of exceeding those standards. The concerns are heightened because 

wood stoves, hydronic heaters, and other heaters are often used around the clock in many

residential areas.

This action is conducted under the authority of section 111 of the CAA, 

"Standards of Performance for New Stationary Sources," under which the EPA 

establishes federal standards of performance for new sources within source categories 

that cause or contribute significantly to air pollution, which may reasonably be 

anticipated to endanger public health or welfare. Consistent with section 111(h), if it is 

not feasible to prescribe or enforce a standard of performance, the Administrator may

instead promulgate a design, equipment, work practice, or operational standard, or 

combination thereof, that reflects the best system of continuous emission reduction,

which (taking into consideration the cost of achieving such emission reduction, and any 

non-air quality, health, and environmental impact and energy requirements) the 

Administrator determines has been adequately demonstrated.

2. Summary of the Major Provisions of this Proposed Regulatory Action

In response to the results of the NSPS review, we are proposing to amend 40 CFR 

part 60, subpart AAA, Standards of Performance for New Residential Wood Heaters. The 

current regulation applies to affected appliances manufactured after 1988. Except as 

 

1

Strategies for Reducing Residential Wood Smoke. EPA-456/B-13-001, March 2013. 

Prepared by Outreach and Information Division, Air Quality Planning Division, Office of 

Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research 

Triangle Park, NC 27711. pp. 4-5.
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discussed in this proposal, the current requirements would remain in effect for the heaters 

and model lines manufactured before this proposal. We propose to broaden the 

applicability of the regulation beyond adjustable burn rate wood heaters (the focus of the 

original regulation), to specifically include all single burn rate wood heaters/stoves and 

pellet heaters/stoves. (Some pellet heaters/stoves were not affected by the 1988 

regulation.) Note that this preamble uses the following terms interchangeably: heaters, 

stoves, and heaters/stoves. Heaters/stoves and model lines manufactured after the 

effective date of the rule would be required to meet particulate matter (PM) standards. 

As with the 1988 regulation, the source category covered by this NSPS is 

fundamentally different from the typical NSPS source category in several ways. For 

example, typically these heaters are installed and operated in residences, not industrial or 

commercial facilities. Also, residential wood heaters, hydronic heaters, forced-air 

furnaces, and most masonry heaters are mass-produced consumer items, rather than 

industrial processes typically regulated by NSPS. As with the 1988 regulation, because 

heaters are mass-produced residential consumer items, a compliance approach requiring 

each heater to be tested would be very costly. The cost of a test series is several times the 

cost of a typical wood heater. Over 95 percent of the manufacturers are small businesses. 

Therefore, as in 1988, we are proposing to permit that manufacturers avoid testing every

heater by allowing a certification program whereby representative heaters are tested. If 

the representative heater meets the applicable emission limits, the entire model line could 

be certified. Individual heaters within the model line would still be subject to all other 

requirements, including labeling and operational requirements. Manufacturers would be 

required to have quality assurance programs to ensure that all heaters within the model 
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line conform to the certified design and meet the applicable emission limits. The EPA 

would also have the authority to conduct audits to ensure compliance. We ask for 

comments on all aspects of this approach, especially whether more than one 

representative heater should be tested prior to certification of the model line.

To also address some of the specific characteristics of this source category, as in 

the 1988 regulation, we are proposing a two-step compliance approach that would 

provide a reasonable, phased implementation of emission limits for manufacturers (again, 

over 95 percent are small businesses) that need lead time to develop, test, field evaluate, 

and certify current technologies across their consumer product lines. Also, as in 1988, 

there could be “logjam” concerns about the capacity of accredited laboratories to conduct 

certifications tests and for the EPA to review the tests and to adequately assure 

compliance if all the NSPS requirements were to be immediate. Thus, upon the effective 

date of this rule (which we expect will occur in 2014), new heaters/stoves would be 

required to meet a PM limit of 4.5 grams per hour (g/hr) as proposed in Step 1. Five years 

later, new heaters/stoves would be required to meet a PM limit of 1.3 g/hr as proposed in 

Step 2.

Each unit would be equipped with a permanent NSPS label. Additional 

requirements would apply to entities other than the manufacturer. The wood heater test 

laboratory would be subject to quality assurance requirements. We would continue to 

require the proper burn practices that currently apply to the owner or operator of a wood 

heating appliance. In addition, new pellet heater/stove owners and operators would be 

required to use only the grade of licensed pellet fuels that are included in the heater/stove

certification tests, or better. We are proposing to streamline the current enforcement and 
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audit provisions of the current subpart to reflect changes in industry practices and 

development of new tools and procedures. We are proposing improvements to the 

previous test methods as well as new test methods.

We are also proposing new subpart QQQQ, which would apply to new woodfired residential hydronic heaters and forced-air furnaces, and new subpart RRRR, which 

would apply to new residential masonry heaters. These new subparts are being proposed 

to address the EPA’s findings that additional heater appliance types should be regulated 

under the NSPS program. Again, because of the specific aspects of these consumer 

product heaters/furnaces versus typical industrial processes, both subparts are designed 

using principles similar to those in subpart AAA, i.e., certification testing of a 

representative unit in a model line, label requirements, associated quality assurance 

requirements, and phased implementation. Subpart RRRR has some additional features to 

address very small volume manufacturers, including a proposed compliance extension 

and ability to use a software certification approach rather than a laboratory emission test.

In addition, because of the specific characteristics of these source categories, the 

proposed PM standards for subparts QQQQ and RRRR would be implemented in two 

steps. For subpart QQQQ, upon the effective date of the rule, hydronic heaters would be 

required to meet a PM limit of 0.32 pound per million British thermal unit (lb/MMBtu)

output and forced-air furnaces would be required to meet a PM limit of 0.93 lb/MMBtu

heat output. Five years later, both hydronic heaters and forced-air furnaces would be 

required to meet a PM limit of 0.06 lb/MMBtu heat output. For subpart RRRR (masonry

heaters), upon the effective date of the rule, large manufacturers (defined as 

manufacturers constructing greater than or equal to 15 masonry heaters per year) would 
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be required to meet a PM limit of 0.32 lb/MMBtu heat output. Five years later, small 

volume masonry heater manufacturers (defined as manufacturers constructing less than 

15 masonry heaters per year) would be required to meet the 0.32 lb/MMBtu heat output 

PM limit.

3. Costs and Benefits

Consistent with the recently issued Executive Order 13563, “Improving 

Regulation and Regulatory Review,” we have estimated the cost and benefits of the 

proposed rule. The estimated net benefits of our proposed rule at a 3 percent discount rate 

are $1.8 billion to $4.2 billion or $1.7 billion to $3.7 billion at a 7 percent discount rate.

Table 1 is a summary of the results of the analysis. We have provided estimates reflecting 

average annual impacts for the 2014 to 2022 timeframe, which are the years in which the 

options considered in this proposal are implemented.

Table 1. Summary of the Monetized Benefits, Annualized Social Costs and Net Benefits 

for the Proposed Rule (Millions of 2010$)a,b,c

3% Discount Rate 7% Discount Rate

Total Monetized Benefitsb

$1,800 to $4,200 $1,700 to $3,700

Total Annualized Social Costsc$16 $16

Net Benefits $1,800 to $4,100 $1,700 to $3,700

Non-monetized Benefits 33,000 tons of carbon monoxide reductions

3,200 tons of volatile organic compounds reductions

Reduced exposure to hazardous air pollutants, 

including formaldehyde, benzene, and polycyclic 

organic matter

Reduced climate effects due to reduced black carbon 

emissions

Reduced ecosystem effects

Reduced visibility impairments

aAll estimates are for the 2014-2022 timeframe and are rounded to two significant 

figures. These results include units anticipated to come to the market and the lowest cost 
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disposal assumption.

b

The total monetized benefits reflect the human health benefits associated with reducing 

exposure to PM2.5 through reductions of directly emitted PM2.5. It is important to note that 

the monetized benefits include many but not all health effects associated with PM2.5

exposure. Benefits are shown as a range from Krewski et al. (2009) to Lepeule et al. 

(2012). These models assume that all fine particles, regardless of their chemical 

composition, are equally potent in causing premature mortality because the scientific 

evidence is not yet sufficient to allow differentiation of effect estimates by particle type.

c

The compliance costs of the proposal serve as a proxy for the social costs. The 

compliance costs are estimated using a 7 percent interest rate.

B. Does this action apply to me?

The potentially regulated sources that are the subject of this proposal are listed in 

Table 2 of this preamble. Table 2 is not intended to be exhaustive, but rather provides a

guide for readers regarding entities likely to be affected by this proposed action. This

standard, and any changes considered in this rulemaking, would be directly applicable to 

sources as a federal program. Thus, federal, state, local and tribal government entities are 

not affected by this proposed action.

Table 2. Potentially Regulated Entities

Category NAICSa Code Examples of Regulated 

Entities

Residential Wood 

Heating

333414 - Heating Equipment 

(except Warm Air Furnaces) 

Manufacturing

Manufacturers, owners and 

operators of wood heaters, 

pellet heaters/stoves, 

hydronic heaters, masonry

heaters

333415 - Air-Conditioning and 

Warm Air Heating Equipment 

and Commercial and Industrial 

Refrigeration Equipment 

Manufacturing

Manufacturers, owners and

operators of forced-air 

furnaces

238140 - Masonry Contractors Manufacturers, owners,

operators and testers of 

masonry heaters

Testing Laboratories 541380 - Testing laboratories 

(except medical, veterinary)

Testers of wood heaters, 

pellet heaters/stoves, 

hydronic heaters and 

masonry heaters
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aNorth American Industry Classification System

C. Where can I get a copy of this document?

In addition to being available in the docket, an electronic copy of this proposal 

will also be available on the World Wide Web (WWW) through the Technology Transfer 

Network (TTN). Following signature by the EPA Administrator, a copy of this proposed 

action will be posted on the TTN’s policy and guidance page for newly proposed or 

promulgated rules at the following address: http://www.epa.gov/ttn/oarpg/new.html. The 

TTN provides information and technology exchange in various areas of air pollution 

control.

D. What should I consider as I prepare my comments for the EPA?

1. Submitting CBI 

Do not submit information containing CBI to the EPA through 

www.regulations.gov or email. Instead, clearly mark the part or all of the information that 

you claim to be CBI and send or deliver only to the following address: Roberto Morales, 

OAQPS Document Control Officer (C404-02), Office of Air Quality Planning and 

Standards, U.S. Environmental Protection Agency, Research Triangle Park, North 

Carolina 27711, Attention Docket ID Number EPA-HQ-OAR-2009-0734. For CBI 

information on a disk or CD-ROM that you mail to the EPA, mark the outside of the disk 

or CD-ROM as CBI and then identify electronically within the disk or CD-ROM the 

specific information that you claim as CBI. In addition to one complete version of the 

comment that includes information claimed as CBI, you must submit a copy of the 

comment that does not contain the information claimed as CBI for inclusion in the public 

docket. If you submit a disk or CD-ROM that does not contain CBI, mark the outside of 
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the disk or CD-ROM clearly that it does not contain CBI. Information not marked as CBI 

will be included in the public docket and the EPA’s electronic public docket without prior 

notice. Information marked as CBI will not be disclosed except in accordance with 

procedures set forth in 40 CFR part 2. 

2. Tips for Preparing Your Comments

When submitting comments, remember to:

 Identify the rulemaking by docket number and other identifying information (subject 

heading, Federal Register date and page number).

 Follow directions. Respond to specific questions and organize comments by a section 

number.

 Explain why you agree or disagree; suggest alternatives and substitute language for 

your requested changes.

 Describe any assumptions and provide any technical information and/or data that you 

used.

 If you estimate potential costs or burdens, explain how you arrived at your estimate in 

sufficient detail to allow it to be reproduced.

 Provide specific examples to illustrate your concerns and suggest alternatives.

 Explain your views as clearly as possible, avoiding the use of profanity or personal 

threats or character assassination.

 Make sure to submit your comments by the comment period deadline.

II. Background 

A. What is the NSPS program?
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Under section 111 of the CAA, "Standards of Performance for New Stationary

Sources," the EPA lists categories of sources that, in EPA’s judgment, cause or contribute 

significantly to air pollution, which may reasonably be anticipated to endanger public 

health or welfare pursuant to section 111(b)(1)(A), and then promulgates federal 

standards of performance for new sources within such category under section 

111(b)(1)(B). At the time the EPA proposes and establishes standards for certain 

pollutants for a source category, the EPA prepares an analysis of the potential costs and 

benefits associated with the NSPS, which includes the benefits from reductions in 

pollutants for which the standards do not set limits. For example, emission reductions

associated with the requirements of this proposed rule will generate health benefits by 

reducing emissions of PM2.5, other criteria pollutants, such as CO, and non-criteria 

hazardous air pollutants (HAP). Consistent with section 111(h), if it is not feasible to 

prescribe or enforce a standard of performance, the Administrator may instead 

promulgate a design, equipment, work practice, or operational standard, or combination 

thereof, which reflects the best system of continuous emission reduction which (taking 

into consideration the cost of achieving such emission reduction, and any non-air quality, 

health, and environmental impact and energy requirements) the Administrator determines 

has been adequately demonstrated. The NSPS do not establish standards of performance 

for existing sources. However, numerous states have acted independent of this rule to 

address new and existing sources as part of state implementation plan (SIP) measures 

necessary to ensure attainment and maintenance of the NAAQS. Several examples are 

discussed in II.E.
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The level of control prescribed by section 111 historically has been referred to as 

“Best Demonstrated Technology” or BDT. To better reflect that section 111 was 

amended in 1990 to clarify that “best systems” may or may not be “technology,” the EPA 

is now using the term “best systems of emission reduction” or BSER. As was done

previously in analyzing BDT, the EPA uses available information and considers the 

emissions reductions and incremental costs for different systems available at reasonable 

cost. The residential wood heaters source category is different from most NSPS source 

categories in that it is for mass-produced residential consumer products. Thus, important 

elements in determining that BSER has been “adequately demonstrated” include the 

significant costs and environmental impacts of delaying production while models with 

those systems are being designed, tested, field evaluated, and certified. As noted earlier 

and discussed more fully later in this preamble, the 2-step approach that the EPA is 

proposing considers these factors. That is, for this rulemaking, the EPA has determined

the appropriate emission limits and compliance deadlines that together are representative 

of BSER. After the emission limits are established, in general, the source may use any

system that meets the emission limits.

Section 111(b)(1)(B) of the CAA requires the EPA to periodically (every 8 years) 

review an NSPS unless it determines “that such review is not appropriate in light of 

readily available information on the efficacy of such standard.” If needed, the EPA must 

revise the standards of performance to reflect improvements in methods for reducing 

emissions, including consideration of what emissions limitation is achieved in practice. 

Numerous stakeholders have suggested that the current body of evidence justifies the 

revision of the current residential wood heaters NSPS to capture the improvements in 
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performance of such units and to expand the applicability of this NSPS to include 

additional residential wood-burning heating devices that are available today. Some 

stakeholders have suggested that the EPA develop additional NSPS to regulate other

residential heating devices and those that burn fuels other than or in addition to wood, 

e.g., coal, corn or grass.

B. Why was the original residential wood heaters NSPS developed?

The development of the residential wood heater regulations began in the mid1980s in response to the growing concern that wood smoke contributes to ambient air 

quality-related health problems. Several state and local governments developed their own 

regulations for wood heaters. Then, in response to a lawsuit filed by New York State and 

the Natural Resources Defense Council (NRDC), the EPA agreed to initiate a residential 

wood heaters NSPS rulemaking, with a schedule calling for final action by January 31, 

1988. The original standard was developed using a regulatory negotiation process with 

the key stakeholders (the wood heating industry, state governments, and environmental 

and consumer groups) under the Federal Advisory Committee Act (FACA).

Pursuant to CAA section 111(b)(1)(A), the EPA listed the residential wood heater 

source category based on its determination that wood heaters cause, or contribute 

significantly to, air pollution which may reasonably be anticipated to endanger public 

health or welfare (52 FR 5065, February 18, 1987). The EPA also proposed regulations 

for residential wood heaters (52 FR 4994, February 18, 1987). The final standards were

published on February 26, 1988 (53 FR 5860). At the time the original NSPS was 

proposed, the EPA estimated that a typical pre-NSPS conventional wood heater emits 
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about 60 to 70 g/hr of PM and that a wood heater complying with the NSPS would emit 

75 to 86 percent less than conventional wood heaters.

C. What are the requirements of the current 1988 NSPS?

The current subpart AAA defines a wood heater as an enclosed, wood-burning 

appliance capable of and intended for space heating or domestic water heating that meets 

all of the following criteria:

1. An air-to-fuel ratio (ratio of the mass of combustion air introduced into the 

firebox to the mass of dry fuel consumed) in the combustion chamber averaging less than 

35-to-1 as determined by the test procedure prescribed in 40 CFR 60.534 performed at an 

accredited laboratory;

2. A usable firebox volume of less than 0.57 cubic meters (20 cubic feet);

3. A minimum burn rate (weight of dry test fuel consumed per hour) of less than 

5 kilograms per hour (kg/hr) (11 pounds per hour (lb/hr)) as determined by the test 

procedure prescribed in 40 CFR 60.534 performed at an accredited laboratory; and

4. A maximum weight of 800 kg (1,760 lb), excluding fixtures and devices that 

are normally sold separately, such as flue pipe, chimney, and masonry components that 

are not an integral part of the appliance or heat distribution ducting.

In the 1988 rulemaking, the EPA identified several types of residential wood 

combustion appliances that are not subject to the current 1988 NSPS:

 Open masonry fireplaces constructed on site

 Boilers/Heaters

 Furnaces

 Cookstoves
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In addition, the current 1988 NSPS exempts the following from the emission 

limits:

 Wood heaters used solely for research and development (R&D) purposes 

 Wood heaters manufactured for export

 Coal-only heaters

As noted earlier, because of the specific characteristics of this source category

(e.g., it applies to mass-produced residential consumer items), the residential wood 

heaters NSPS (also sometimes informally referred to as the wood stove NSPS) allows 

compliance for model lines to be certified “pre-sale” by the manufacturers. A typical

NSPS source category approach that imposes emission standards and then requires a unitspecific compliance demonstration would have been very costly and impractical. 

Therefore, this NSPS was designed to allow manufacturers of wood heaters to avoid 

having each unit tested by allowing, as an alternative, a certification program that is used 

to test representative wood heaters on a model line basis. Once a model line is certified, 

all of the individual units within the model line are subject to labeling, operational and 

other requirements. Manufacturers are then required to conduct a quality assurance 

program to ensure that appliances produced within a model line conform to the certified 

design and meet the applicable emission limits. There are also provisions for the EPA to 

conduct audits to ensure compliance.

As discussed in the 1988 rulemaking, the standards limiting PM emissions from 

wood heaters in the current NSPS were phased in for this source category because of the 

need to consider the costs of delayed production while new models were being developed 

and certified. Advanced technology heaters/stoves including both catalytic and 
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noncatalytic systems were considered to be BDT (now called BSER), because the net 

emissions of both systems over time were estimated to be similar (even though the initial 

certification test results were lower for catalytic models) due to possible degradation and 

lack of catalyst replacement. The EPA considered requiring catalyst replacement on a 

regular schedule but determined that enforcement of such a requirement would be 

difficult or impractical. The EPA did require manufacturers to provide 2-year 

unconditional warranties on the catalysts and prohibited the operation of catalytic 

heaters/stoves without a catalyst. Principally because of these concerns, the EPA wanted 

to ensure that both catalytic and noncatalytic technology would continue to be options for 

manufacturers to use and further develop. The Phase I standards were very similar to the 

Oregon Department of Environmental Quality standards that had been in existence for a 

few years. The Phase II standards, which are still in effect, are more stringent and had to 

be met within 2 years of publication of the final rule, i.e., by 1990. Models equipped with 

a catalytic combustor cannot emit more than a weighted average of 4.1 g/hr (of PM). 

Models that are not equipped with a catalytic combustor cannot emit more than a 

weighted average of 7.5 g/hr of PM. The lower initial emission limit for the catalytic 

combustor-equipped models incorporates an expected deterioration rate for the catalysts 

such that after 5 years the emissions from those models were expected to be similar to the 

emissions from noncatalytic models. 

D. What are the major developments since the original NSPS was published?

New systems for residential wood heating devices are commercially available in 

the U.S. that perform at significantly lower g/hr emission rates than required under the 

current 1988 NSPS. Furthermore, even greater performance potentially can be achieved 
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by greater deployment of the best U.S. systems and the typical systems already widely 

employed in Europe, especially for outdoor and indoor hydronic heaters. The EPA has 

conducted a research project “Environmental Characterization of Outdoor Wood-fired 

Hydronic Heaters” through a cooperative Research and Development (R&D) agreement 

with the New York State Energy Research and Development Authority (NYSERDA) that 

evaluated four types of technology ranging from a common outdoor wood boiler/heater to 

a state-of-the-art, high-efficiency pellet boiler/heater from Austria. The study showed 

considerable emission reduction due to a 2-stage combustion technology that includes

gasification of the fuel and more complete combustion.2

Stakeholders have expressed concern to the EPA about a broad range of 

residential wood heating appliances that are not addressed by the current 1988 NSPS. 

These include single burn rate wood heaters; pellet heaters/stoves that are not subject to 

the current standard via the NSPS air-to-fuel ratio; wood “boilers” (hydronic heaters);

forced-air furnaces; and masonry heaters. Some stakeholders have also expressed an

interest in regulating non-“heater” devices, such as fireplaces, cookstoves, and pizza 

ovens. 

One category of wood heating appliances that has undergone significant growth is 

wood heaters/boilers or “hydronic heaters.” (Note that these units are technically called 

heaters rather than boilers because many are not pressurized and do not boil the liquid.)

Hydronic heaters are typically located outside the buildings they heat in small sheds with 

short smokestacks. These appliances burn wood to heat a liquid (water or a water-

 

2

Environmental, Energy Market, And Health Characterization Of Wood-Fired

Hydronic Heater Technologies. Prepared by U.S. EPA Office of Research and 

Development, et al., prepared for NYSERDA. June 2012.
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antifreeze mixture) that is piped to provide heat and hot water to occupied buildings, such 

as homes. Often, in addition to supplying heat for homes, the same unit is used to provide 

heat for barns and greenhouses and to provide warm water for swimming pools. Hydronic 

heaters may also be located indoors and may use other biomass (such as corn or wood 

pellets) or coal or a combination for fuel.

Studies have shown that PM2.5 concentrations in proximity to a typical outdoor 

hydronic heater (aka outdoor wood boiler) can exceed the 24-hour NAAQS.

3

Thus, the 

EPA developed a hydronic heater voluntary partnership program in order to encourage 

manufacturers to reduce impacts on air quality through developing and distributing 

cleaner, more efficient hydronic heaters. We developed the voluntary partnership 

program with the goal of bringing cleaner models to market faster than the traditional 

federal regulatory process. Phase 14emission level (0.60 lb/MMBtu heat input) 

qualifying5units are approximately 70 percent cleaner than typical unqualified units. 

After March 31, 2010, units that only meet the Phase 1 emission level are no longer 

considered “qualified models” under the voluntary partnership program. Phase 2 

emission level (0.32 lb/MMBtu heat output) qualifying units are estimated to be 

 

3

For more information on wood smoke health effects, see: “Smoke Gets in Your Lungs: 

Outdoor Wood Boilers in New York State,” prepared by Judith Schrieber, Ph.D., et al., 

for the Office of the Attorney General of New York. August 2005. See also: “Assessment 

of Outdoor Wood-fired Boilers,” prepared by NESCAUM, March 2006 (revised June 

2006).

4

“Phase 1” and “Phase 2” emission levels refer to levels established in EPA voluntary

partnership programs. The earlier use of the term “Phase II” (with a Roman numeral) 

standard refers to standards established in the current subpart AAA for residential wood 

heaters. 

5

The terms “qualified” and “unqualified,” or other similar terms, refer to models that 

meet or have not been shown to meet the voluntary partnership program performance 

levels. Later use of the terms “certified” and “uncertified,” or other similar terms, refers 

to models that are deemed to be in compliance or noncompliance with the NSPS emission 

limits.
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approximately 90 percent cleaner than typical unqualified units. Typically, qualified 

models have improved insulation, secondary combustion, separation of the firebox from 

the water jacket, and the addition of improved heat exchangers. 

In addition to the voluntary partnership program, the EPA provided technical and 

financial support for the Northeast States for Coordinated Air Use Management 

(NESCAUM) to develop a model rule that several states have adopted to regulate 

hydronic heaters. The model rule is a starting point for local regulatory authorities to 

consider, and additional actions may be needed due to site-specific concerns, e.g., local 

terrain, meteorology, proximity of neighbors and other exposed individuals. Thus, some 

regulatory authorities have instituted additional requirements and some have banned

hydronic heaters in some areas.

The EPA also developed a similar voluntary partnership program for low mass 

fireplaces (engineered, pre-fabricated fireplaces) and site-built masonry fireplaces. The 

program began in February 2009, and pertained only to low mass fireplaces at that time. 

In July 2009, the program was expanded to masonry fireplaces. Under this program, 

cleaner burning fireplaces are ones that qualify for the Phase 1 emissions level of 7.3 

grams of particles emitted per kilogram (g/kg) of fuel burned (approximately 57 percent 

cleaner than unqualified models) or the Phase 2 emissions level of 5.1 g/kg 

(approximately 70 percent cleaner than unqualified models). So far, 36 models have 

qualified under this voluntary partnership program at the Phase 2 level. Typically, 

qualified models have improved insulation and added secondary combustion and/or a

catalyst to reduce emissions. Some manufacturers have added doors to reduce the excess 

air and thus improve combustion. The Phase 2 emission level in the voluntary fireplace 
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program has been considered as a starting point for some local regulatory authorities, and 

additional actions have also been considered due to site-specific concerns, e.g., local 

terrain, meteorology, proximity of neighbors and other exposed individuals, and 

magnitude of other emissions in the airshed. Thus, some regulatory authorities have 

instituted additional requirements (e.g., no burn days) and some have banned new woodburning fireplaces in some areas. 

The current NSPS in subpart AAA have been in effect for over 24 years and 

manufacturers and test laboratories have gained considerable experience in complying 

with the requirements of the program. As a result, manufacturers and test laboratories 

have suggested changes to the certification process to better implement the program, such 

as developing an electronic system for submittals and approval. Manufacturers and test 

laboratories have also questioned the effectiveness of some of the current audit 

procedures. In addition, they have participated in the development of new test methods 

and test method improvements as part of the efforts of ASTM International (formerly 

known as the American Society of Testing and Materials). While the NSPS left a 

placeholder for development of an efficiency standard for use in subpart AAA, one has 

not been developed by the EPA. However, on June 1, 2007, the EPA approved the 

Canadian Standards Association (CSA) stack loss method in B415 as an alternative for 

wood heater efficiency testing in subpart AAA provided that the tests use the same burn 

rate categories specified in the EPA Reference Method 28. We are proposing that the 

current version of this method be used for efficiency testing (CSA B415.1-10). We are 

also proposing EPA Method 28 WHH (wood-fired hydronic heaters) that has been used 

for qualification testing of hydronic heaters in the EPA voluntary partnership program 
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and numerous state regulations. Other issues that have been identified over the years 

regarding test methods and emissions calculations include emissions averaging, burn rate 

weightings, hot start versus cold start, emission caps per burn rate, and catalyst 

degradation. Another issue is whether to change current requirements to conduct 

certification tests with “crib” wood instead to “cord” wood. (“Crib wood” is a specified 

configuration and quality of dimensional lumber and spacers, which was intended to 

improve the repeatability of the test method in 1988. “Cord wood” is a different specified 

configuration and quality of wood that is intended to more closely resemble what a 

typical homeowner would use.) We address these issues as part of this proposal.

E. Why is residential wood smoke a concern?

There is increasing recognition of the health impacts of particle pollution, to

which wood smoke is a contributing factor in many areas. Wood smoke contains a 

mixture of gases and fine particles that can cause immediate effects, including burning 

eyes, runny nose and bronchitis. Exposure to fine particles has been associated with a 

range of health effects, including aggravation of heart or respiratory problems (as 

indicated by increased hospital admissions and emergency department visits), changes in 

lung function and increased respiratory symptoms, as well as premature death. 

Populations at greater risk for experiencing health effects related to fine particle 

exposures include older adults, children and individuals with pre-existing heart or lung 

disease.6 Residential wood smoke contains fine particles and toxic air pollutants (e.g.,

benzene and formaldehyde). Each year, smoke from wood heaters contributes hundreds 

of thousands of tons of fine particles throughout the country – mostly during the winter 

 

6

EPA Burn Wise (Consumer - Health Effects), 

http://www.epa.gov/burnwise/healtheffects.html.
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months. Nationally, residential wood combustion accounts for 44 percent of total 

stationary and mobile POM emissions, nearly 25 percent of all area source air toxics 

cancer risks, and 15 percent of noncancer respiratory effects.

7

In a number of communities, residential wood smoke can increase particle 

pollution to levels that cause significant health concerns (e.g., asthma attacks, heart 

attacks, premature death). Several areas with wood smoke problems either exceed the 

EPA’s health-based NAAQS for fine particles or are on the cusp of exceeding those 

standards. For example, in places such as Keene, New Hampshire; Sacramento, 

California; Tacoma, Washington; and Fairbanks, Alaska; wood combustion can 

contribute over 50 percent of daily wintertime fine particle emissions.

8

In December 2012, the EPA issued revised NAAQS for PM to provide increased 

protection of public health and welfare. The 2012 NAAQS for PM strengthens the annual 

NAAQS for fine particles to 12 micrograms per cubic meter (μg/m3) and retains the 

existing 24-hour fine particle standard of 35 μg/m3 issued in 2006. The 2012 NAAQS for 

PM also retains the current 24-hour PM10 standards for health and environmental effects 

at a level of 150 μg/m3to continue to provide protection against effects associated with 

exposure to thoracic coarse particles. Areas that do not meet the standards must take steps 

to reduce PM emissions. Some state organizations have argued that more stringent

standards for new wood heating devices would provide a much needed tool for states and 

 

7

Strategies for Reducing Residential Wood Smoke. EPA-456/B-13-001, March 2013. 

Prepared by Outreach and Information Division, Air Quality Planning Division, Office of 

Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research 

Triangle Park, NC 27711. pp. 4-5.

8 Memorandum dated April 4, 2013, from David Cole, EPA, to Docket ID No. EPA-HQOAR-2009-0734 .
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local communities to use in addressing the growth of pollution from these sources.9, 10

Recent health studies considered in the review of the PM NAAQS confirm the impacts on 

public health. The latest information on the PM NAAQS reviews is at

http://www.epa.gov/pm/actions.html.

There is also concern about the health effects of other pollutants found in wood 

smoke. In addition to PM, wood smoke contains harmful chemical substances such as 

CO, formaldehyde and other organic gases, and nitrogen oxides (NOx).

Health effects from CO include:

 Interference with the blood’s ability to carry oxygen to the brain, which impairs 

thinking and reflexes

 Heart pain

 Lower birth weights and increased deaths in newborns

 Death

Health effects from formaldehyde and other organic gases include: 

 Irritation of eyes, nose, and throat

 Inflammation of mucous membranes, irritation of the throat and sinuses

 Interference with lung function

 Allergic reactions

 Nose and throat cancer in animals, and cancer in humans

 

9 Arthur Marin, Executive Director of NESCAUM and Dan Johnson, Executive Director 

of WESTAR, to Steve Page, Director OAQPS/EPA. April 28, 2008.

10 Arthur Marin, Executive Director of NESCAUM, to Gina McCarthy, Assistant 

Administrator for Air and Radiation/EPA. January 14, 2011.
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Nitrogen oxide can irritate the eyes and respiratory system, may damage the 

immune system by impairing the body’s ability to fight respiratory infection and can 

affect lung function.11

Residential wood combustion emissions contain potentially carcinogenic 

compounds including formaldehyde, polycyclic aromatic hydrocarbons (PAHs), benzene, 

and dioxin, which are toxic air pollutants; but their effects on human health via exposure 

to wood smoke have not been studied as extensively.

12

We realize that many areas of the country are struggling with reducing PM 

emissions due to residential wood smoke from existing wood-burning appliances that will

not be affected by this rule. In addition, due to the long life span of wood-burning 

appliances and slow turnover, it may be many years before the full impacts of these 

regulations on new appliances can be felt. However, there are strategies to reduce wood 

smoke that states, counties and townships can take independent of this rule.

13 Some states 

have direct legislative authority, and all states have authority to address new and existing 

sources as SIP measures necessary to ensure attainment and maintenance of the NAAQS. 

For examples, the State of Oregon, Washoe County (NV), and Township of Mammoth 

Lakes (CA) have required that existing wood heaters that have not been certified to meet 

the NSPS be removed and destroyed and not resold when a home is sold. As additional 

SIP strategies, some states and local authorities have banned wood burning during certain 

high PM events, restricted the amount of burning, and regulated the type of materials 

 

11 Department of Ecology, State of Washington, Brochure on Wood Smoke and Your 

Health. September 2008, http://www.ecy.wa.gov/pubs/91br023.pdf.

12 EPA Burn Wise (Health Effects of Breathing Wood Smoke), 

http://www.epa.gov/burnwise/pdfs/woodsmoke_health_effects_jan07.pdf.

13 "Strategies for Reducing Residential Wood Smoke," EPA-456/B-13-001. March 2013.
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being burned. Non-regulatory programs, such as education programs to teach the public 

how to use their wood-burning appliances in ways that minimize emissions, have also 

been successful. The EPA has also implemented programs that encourage good burning 

practices, which have a significant impact on emissions. The EPA, some state and local 

agencies, and other stakeholders, including the Hearth, Patio and Barbecue Association

(HPBA), have been active in promoting wood heater/stove changeout programs to 

replace older, dirtier heaters/stoves with lower-emitting EPA-certified heaters/stoves, 

pellet heaters/stoves, or other cleaner burning appliances.

F. What are the major issues that drove the review process?

We received several requests to conduct a review of the residential wood heaters

NSPS, including a joint letter from the Western States Air Resources Council 

(WESTAR) and NESCAUM that urged us to update and develop regulations relating to a 

variety of wood combustion devices. The authors cited concerns that many communities 

are measuring ambient conditions above or very close to the PM2.5 NAAQS and that, in 

many instances, emissions from wood smoke are a large contributor to those high PM2.5 

levels. Other states, environmental groups, and HPBA have also recommended several 

changes to the NSPS. The HPBA Outdoor Wood-fired Hydronic Heater (OWHH)

Manufacturers Caucus wrote the EPA to express their unanimous support for the EPA to 

develop a federal regulation for OWHH.

14

Specific requests from stakeholders include:

 Tightening emission standards based on current performance data

 Addressing other pollutants of concern

 

14 HPBA OWHH Caucus letter to Greg Green, Director, Outreach and Information 

Division, EPA. September 27, 2007.
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 Reviewing the format of the standards, including adding requirements to document 

the tested efficiency of the unit

 Reevaluating exemptions, such as those based on air-to-fuel ratios and size and 

weight

 Adding other wood heating devices such as pellet heaters/stoves, hydronic heaters, 

and masonry heaters to the NSPS

 Regulating fireplaces and other “non-heater” devices (e.g., cookstoves)

 Regulating heating devices that burn fuel other than wood (e.g., other solid biomass

and coal)

 Updating test methods 

 Streamlining the certification process to use electronic data submittals/reviews

 Considering use of International Organization for Standardization (ISO)-accredited 

labs and ISO-accredited certifying bodies

 Improving compliance assurance/enforceability and quality assurance/quality control

 Making the rule more consumer friendly by making more information readily

available on-line

III. Summary of Proposed Residential Wood Heater Appliance Amendments 

We are proposing to amend 40 CFR part 60, subpart AAA, Standards of 

Performance for New Residential Wood Heaters. We are also proposing two new 

subparts to address additional types of wood heating appliances. Specifically, we are 

proposing subpart QQQQ, Standards of Performance for New Residential Hydronic 

Heaters and Forced-Air Furnaces, and subpart RRRR, Standards of Performance for New 

Residential Masonry Heaters. The following sections describe the major provisions of 
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each subpart. This proposal does not include any requirements that would apply to

heaters that are fueled solely by gas, oil or coal.

A. Room Heaters

The current regulation (subpart AAA) applies to affected appliances

manufactured since 1988. Except as discussed in this proposed action, the current

requirements would remain in effect for the heaters manufactured before this proposal. 

For units manufactured after the compliance dates, we propose to broaden the 

applicability of the wood heaters regulation beyond adjustable burn rate wood heaters 

(the focus of the original regulation) to specifically include single burn rate wood heaters, 

pellet heaters/stoves, and any other affected appliance as defined in subpart AAA as a 

“room heater.” The proposed subpart AAA does not apply to new residential hydronic 

heaters, new residential forced-air furnaces, and new residential masonry heaters because 

they would be subject to their own subparts. Like the current subpart AAA, the proposed 

subpart AAA does not apply to fireplaces. This proposal tightens the definition for 

“cookstoves” and adds definitions for “camp stoves” and “traditional Native American 

bake ovens” to clarify that they would not be subject to the standard other than 

appropriate labeling for cookstoves and camp stoves. Finally, the proposed subpart AAA 

clarifies that the emission limits would only apply to wood-burning devices (i.e., not to 

devices that only burn fuels other than wood, e.g., gas, oil or coal).

As discussed in section II, NSPS determinations of BSER must consider costs. 

The fact that this source category is for consumer products manufactured for residential 

sale results in cost considerations that are different from most NSPS source categories 

that typically are industrial processes. Specifically, if production and sales were to be 
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suspended while designing, testing, field evaluating, and certifying cleaner models, the 

cost of potential lost revenues would be significant, which necessitates reasonable lead 

times for compliance with proposed emission limitations. This was true in 1988, and is 

still true today. Thus, we propose to allow a transition period so that heaters/stoves with 

EPA certification currently in effect can continue to be manufactured until the current 

certification expires (5 years from date of certification) or is revoked by the 

Administrator, whichever date is earlier. We would not allow renewal of these 

certifications. That is, in the near term, we are proposing to retain the current Phase II PM 

emission limits (issued in the current 1988 standards for compliance in 1990) for 

adjustable burn rate wood heaters and pellet heaters/stoves with a current EPA 

certification issued prior to the effective date of the proposed emission limits, and we 

intend to promulgate them in 2014. (For simplicity of discussions in this preamble, we 

are using “2014” as shorthand for the expected effective date of the final rule. If the 

expected effective date of the final rule changes from 2014, we will adjust the 

compliance date.) While our top priorities are to ensure that emission reductions occur in 

a timely manner and that there is no backsliding from the improvements that many

manufacturers have already made, we have also sought to avoid unreasonable economic 

impacts on those manufacturers (mostly small businesses) who need additional time to 

develop a full range of cleaner models and to avoid potential “logjams” at laboratories 

conducting certification testing. We ask for specific comments on the length of this 

proposed transition and the degree to which there would be any critical economic impacts 

on manufacturers who have heaters with current certifications if we were to not allow up 

to the full 5-year certification period for units manufactured after the effective date of the 
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final rule. We also ask for specific comments on allowing grandfathering of models that 

are tested in good faith according to the proposed test methods and the proposed emission 

limits, even though the final test methods may differ from this proposal.

We are proposing a two-step compliance approach (referred to herein as the 

“Proposed Approach”) that would apply to all new adjustable burn rate wood heaters, 

single burn rate wood heaters and pellet heaters/stoves. Under this Proposed Approach, 

the Proposed Step 1 emission limits for these sources would apply to each source

manufactured on or after the effective date of the final rule or sold at retail on or after the 

date 6 months from the effective date of the final rule. Proposed Step 2 emission limits

for these sources would apply to each adjustable rate wood heater, single burn rate wood 

heater and pellet heater/stove manufactured or sold on or after the date 5 years after the 

effective date of the final rule. We ask for specific comments on the Proposed Approach 

and the degree to which these dates could be sooner. 

We are also asking for comments on a three-step compliance approach (referred 

to herein as the “Alternative Approach”) for all adjustable rate wood heaters, single burn 

rate wood heaters and pellet heaters/stoves. Under this Alternative Approach, the 

Alternative Step 1 emission limits would apply to each source manufactured on or after 

the effective date of the final rule or sold at retail on or after the date 6 months from the 

effective date of the final rule. (Thus, Step 1 under the Alternative Approach is the same 

as Step 1 under the Proposed Approach.) The Alternative Step 2 emission limits would 

apply to each source manufactured or sold on or after the date 3 years after the effective 

date of the final rule. The Alternative Step 3 emission limits would apply to each source 

manufactured or sold on or after the date 8 years following the effective date of the final 
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rule (thus providing 5 years between the Alternative Step 2 and Alternative Step 3). We 

ask for specific comments on this Alternative Approach, including data and potential 

environmental and economic impacts on this alternative, and the degree to which the

Alternative Approach emission levels and dates could be considered BSER. Our current 

preference is the Proposed Approach, but we intend to finalize a single compliance 

approach after fully considering the comments received during the public comment 

period on this proposed rulemaking. 

Table 3 summarizes the PM emissions standards that would apply to each wood 

heater appliance under this Proposed Approach at each step. Table 4 summarizes the PM 

emissions standards that would apply to each wood heater appliance under each step of 

the Alternative Approach. 

Table 3. Proposed Approach Subpart AAA PM Emissions Limits

Appliance Phases/Steps15 PM

Emissions Limit

Adjustable Rate Wood 

Heaters or Pellet 

Heaters/Stoves with 

current EPA certification 

issued prior to the 

effective date of the Final 

Rule

Transition period from 

1988 rule through the 

later of the effective 

date of the final 

revised rule or 

expiration of current 

certification 

(maximum of 5 years 

certification and no 

renewal)

4.1 g/hr for catalytic 

heaters/stoves and 7.5 

g/hr for noncatalytic 

heaters/stoves

All Other Adjustable 

Rate Wood Heaters, 

Single Burn Rate Wood 

Heaters or Pellet 

Heaters/Stoves (includes 

currently certified heaters 

after the certification 

expires, catalytic and 

Step 1: “2014” (upon 

the effective date of 

final rule)

Step 2: “2019” 

(5 years after the 

effective date of the 

final rule)

4.5 g/hr 

1.3 g/hr

 

15 Dates are based on the estimated effective date of the final rule in 2014. If the effective 

date changes, the EPA will change the dates based on the actual effective date.
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noncatalytic) 

Table 4. Alternative Approach Subpart AAA PM Emissions Limits

Appliance Phases/Steps16 PM

Emissions Limit

Adjustable Rate Wood 

Heaters or Pellet 

Heaters/Stoves with 

Current EPA 

Certification Issued Prior 

to the effective date of 

Final Rule

Transition period from 

1988 rule through the 

later of the effective 

date of the final 

revised rule or 

expiration of current 

certification 

(maximum of 5 years 

certification and no 

renewal)

4.1 g/hr for catalytic 

heaters/stoves and 7.5 

g/hr for noncatalytic 

heaters/stoves

All Other Adjustable 

Rate Wood Heaters, 

Single Burn Rate Wood

Heaters or Pellet 

Heaters/Stoves (includes 

currently certified heaters 

after the certification 

expires, catalytic and 

noncatalytic) 

Step 1: “2014” (upon 

the effective date of 

final rule)

Step 2: “2017” 

(3 years after the 

effective date of the 

final rule)

Step 3: “2022” 

(8 years after the 

effective date of the 

final rule)

4.5 g/hr 

2.5 g/hr

1.3 g/hr

Although the 1988 promulgated subpart AAA (53 FR 5860, February 26, 1988) 

included an additional 1-year compliance extension for low-volume manufacturers, i.e., 

companies that manufacture (or export to the U.S.) fewer than 2,000 heaters per year, this

proposal does not include a similar compliance extension. We are not proposing a delay

for adjustable burn rate wood heaters or pellet heaters/stoves because the majority of 

these appliances already comply with the proposed Step 1 emission levels. See section 

 

16 Dates are based on the estimated effective date of the final rule in 2014. If the effective 

date changes, the EPA will change the dates based on the actual effective date.
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V.C. of this preamble for more discussion of this topic. However, we are requesting 

comments on the possible need for such a compliance extension for single burn rate wood 

heaters, which are not subject to the current subpart AAA requirements.

We are proposing to make a single determination of BSER for both catalytic and 

noncatalytic heater systems. The EPA considered requiring catalyst replacement on a 

regular schedule but determined that enforcement of such a requirement would be 

difficult. As in the current 1988 rule, we are proposing to require manufacturers to 

provide warranties on the catalysts and prohibit the operation of catalytic heaters/stoves 

without a catalyst. In addition, we are proposing to require warranties for noncatalytic 

heaters/stoves. Though we are not proposing efficiency standards at this time, we are 

proposing to require testing and reporting of these data; however, we are requesting 

specific comment on the need to propose efficiency standards and any data to support the 

basis for these standards.

We are also proposing to require emission testing and reporting based on both 

crib wood and cord wood for the proposed Step 1 compliance, while allowing 

manufacturers to choose whether to certify with crib wood or cord wood for the proposed 

Step 1. For the proposed Step 2 compliance, we are requiring certifying with cord wood 

only. As discussed earlier in this preamble, “crib wood” is a specified configuration and 

quality of dimensional lumber and spacers that was intended to improve the repeatability

of the test method in 1988. “Cord wood” is a different specified configuration and quality

of wood that is intended today to more closely resemble what a typical homeowner would 

use.
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Although we lack sufficient data to propose a separate CO emissions standard at 

this time, we propose to require that the manufacturer determine CO emissions during the 

compliance test and report those results to the EPA. We specifically request emission and 

cost data for systems that reduce CO emissions. If those systems warrant inclusion in the 

final rule, we would consider doing so. In addition, we ask for specific comments on 

whether the final rule should explicitly require indoor CO monitors as a critical safety 

component for heaters installed in occupied buildings or other buildings or enclosures in 

which the operator would enter to add fuel to the heater or conduct other normal 

operation and maintenance of the heater. Numerous stakeholders have indicated that an 

explicit requirement is needed. 

Like the current subpart, the EPA is using its authority under section 114 of the 

CAA to require each manufacturer to submit certifications of compliance with this rule 

for all models and all units. As in the 1988 rule, provided that the certifications are 

timely, complete, and accurate, the EPA is proposing to allow certification to be 

determined based on testing of a representative unit within the model line. As in 1988, 

the cost of testing each unit would be an order of magnitude greater than the cost of a 

wood heater/stove and would be economically prohibitive. In addition, as in 1988, the 

testing of each unit could create a “logjam” that would stymie the certification of cleaner 

model lines. However, as discussed earlier, we are asking for specific comments on 

whether we should require testing of more than one representative unit prior to 

certification of a model line. The proposed subpart expands the definition of “Accredited 

Test Laboratory,” from only EPA-accredited laboratories to allow laboratories accredited 

by a nationally recognized accrediting body to perform testing for each of the test 
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methods specified in this NSPS under ISO-IEC17 Standard 17025, to conduct the 

certification testing. The laboratories would have to register their credentials with the 

EPA and be approved by the EPA prior to conducting any certification testing or related 

work used as a basis for compliance with this rule. Also, they would be required to report 

any changes in their accreditation and any deficiencies found under ISO 17025, and the 

EPA may revoke the approval if appropriate. 

Our intent is to require the new certification process for certifications that occur 

after the effective date of the final rule. However, we request specific comments on 

whether we should allow a transition period; that is, whether we should retain the current

“Administrator Approval Process” to review the certification application, including test 

results, for the first year following the effective date of the final rule. Note that models 

certified prior to the effective date of the final rule would not have to be re-tested until 

the certification expires. Our proposal is to require a “Certifying-Body-Based 

Certification Process,” upon the effective date of the final rule. Under this process, after 

testing is complete, a certification of conformity with the PM emissions standards must 

be issued by a certifying body with whom the manufacturer has entered into contract for 

certification services. The certification body would have to be accredited under ISO-IEC 

Standard 17065 and register their credentials with the EPA and receive EPA approval 

prior to conducting any certifications or related work used as a basis for compliance with 

this rule and report any changes in their accreditation and any deficiencies found under 

ISO 17065. The EPA would oversee the certification body’s work and retain the right to 

revoke the approval if appropriate. Upon review of the test report and quality control plan 

 

17 ISO, the International Organization for Standardization, and IEC, the International 

Electrotechnical Commission, prepare and publish international standards.
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submitted by the manufacturer, the certifying body may certify compliance and submit 

the required documentation to the EPA’s Office of Enforcement and Compliance 

Assurance for review, approval and listing of the certified appliance.

As in the current 1988 NSPS, each affected unit would be required to have an

applicable permanent label and have an owner’s manual that contains specified 

information. We are proposing that permanent labels would be required for each affected 

unit on the effective date of the final rule. We propose to clarify that the permanent label 

must be installed so that it is readily visible both before and after the unit is installed. 

This clarification is needed to document the use of complying heaters that may be 

required by state and local rules and/or to determine the unit’s applicability to any future 

changeout programs. We also request specific comments on how to best assure that 

manufacturers and retailers and online marketers of wood heaters only use valid 

certification test data and not exaggerated claims.

In the current (1988) NSPS, temporary labels were required for wood heaters that 

are subject to the standards and also for ones that are not (e.g., coal heaters/stoves). These 

temporary labels were intended primarily to contain information useful to consumers and 

prospective wood heater purchasers to be able to compare different appliance models and 

to inform the consumer about the importance of proper operation and maintenance. These 

temporary labels included the wood heater’s compliance status, comparative emission 

and efficiency performance data, and heat output rates and explicitly stated that the 

appliance will achieve low smoke output and high efficiency only if properly operated 

and maintained. The EPA no longer believes these temporary labels are necessary for all 

heaters because we have developed and are continuing to improve our education and 
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outreach program for consumers on selecting the cleanest appliances and wood fuel with 

appropriate moisture content and on the effective use and operation of these appliances. 

See http://www.epa.gov/burnwise. Consequently, we are proposing to remove the

requirement for temporary labels. We request comment on the potential impact that

deleting this requirement might have on a consumer’s ability to select wood heaters that 

meet the proposed standards and are the cleanest and whether we should consider 

developing a voluntary labeling program for the cleanest of the clean. As discussed 

elsewhere, we also ask for specific comments on language that we should require 

manufacturers and retailers to provide to consumers to help explain the relative merits of 

high-performing heaters versus lower-performing heaters.

In addition to the PM emissions standards, we are proposing to continue to 

require the proper burn practices that already apply to the owner or operator of a wood 

heating appliance. That is, the current 1988 standards already include the requirement 

that the owner or operator must operate the heater consistent with the owner’s manual

and not burn improper fuels. Numerous states have expressed their support for the 

continuation of these requirements. Some states and local jurisdictions have enforced 

similar requirements, and this proposal would allow potential delegation of enforcement 

authority of these NSPS requirements upon the EPA approval of state requests.

The proposed revision clarifies that the current requirement to operate according 

to the owner’s manual continues to include a list of prohibited fuel types that create poor 

or even hazardous combustion conditions and includes operation of pellet fuel appliances 

only with the grades of pellet fuels that are included in the certification tests, or better. 

We propose that pellets for the certification tests be only those that have been produced 
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under a licensing agreement with the Pellet Fuels Institute (PFI), or equivalent (after 

request and subsequent approval by the EPA), to meet certain minimum requirements and 

procedures for a quality assurance process. Details of the PFI program are available at 

http://pelletheat.org/pfi-standards/pfi-standards-program/. We believe that these 

provisions are necessary to ensure that the appliances operate properly such that 

emissions are reduced as intended. We ask for specific comments on whether we should 

include other requirements of best burn practices or adjustments to help ensure proper 

operation, e.g., chimney height and draft specifications, moisture content of wood and 

limits on visible emissions.

The proposed subpart still contains the crucial quality assurance provisions in the 

current 1988 NSPS. A comprehensive discussion of the rationale is included in the 1988 

preamble. For example, a model line must be recertified whenever any change is made in 

the original design that could affect the emissions rate for that model line or when any of 

several specified tolerances of key components are changed. The current requirements for 

manufacturer quality assurance programs would be superseded by a Certifying-BodyBased Quality Assurance program. (As noted earlier, we would not require retesting for 

models that are certified prior to the effective date of the final rule until the certification 

expires or is revoked.) The Certifying Body would conduct regular, unannounced audits 

to ensure that the manufacturer’s quality control plan is being implemented properly.

The EPA audit testing programs of the current 1988 NSPS will be maintained 

under the proposed changes, although they will be streamlined and simplified to better 

ensure compliance and to clarify that audits can be based on any information the EPA has 

available and do not have to be statistically random. Also, we clarify that the EPA and 
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states are allowed to be present during the audits and that states (and other entities, 

including the public) may provide the EPA with information that may ultimately be used 

in the EPA enforcement and compliance assurance efforts. 

As discussed earlier, the EPA developed Method 28 in 1987 and 1988 as part of 

our efforts on the current 1988 NSPS. We received input at that time from manufacturers, 

laboratories, and some states. Oregon Method 7 was the starting point for Method 28 and,

thus, Method 28 has many aspects similar to Oregon Method 7. The details on the history

and development of Method 28 are contained in the February 18, 1987, proposal in the 

Federal Register (52 FR 5003) and the February 26, 1988, final rule in the Federal 

Register (53 FR 5866).

The manufacturers, laboratories, states and the EPA have now had more than 25

years of experience with Method 28, and it has been very useful for certifying hundreds 

of model lines of wood heaters/stoves. We asked the manufacturers, EPA-accredited 

laboratories and states for their insights on Method 28. Many stakeholders agree that

changes should be made to improve the reproducibility and repeatability of the test 

procedures and to address concerns about how to best ensure protection across the entire 

U.S. when various operating scenarios are used and various wood species and densities 

are used. For example, to address some of these concerns, ASTM has used a “consensusbased” process to develop E2515-10 “Standard Method for Determination of Particulate 

Matter Emissions in a Dilution Tunnel.” The EPA is proposing that this sampling and 

analysis method be used for all of the appliances in this rulemaking. As with all test 

methods, there are opportunities for continual improvement, and the EPA requests 

specific comments and supporting data for additional potential improvements to E2515-
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10. 

A number of states have expressed concern about ASTM’s Intellectual Property

Policy which requires all participants to give their intellectual property rights to ASTM 

so that, in turn, ASTM can control distribution of the drafts and final test methods and 

sell the final test methods to potential users. Attorneys General for several states have 

indicated that state employees in their states cannot give to ASTM the property rights for 

property that their states paid for via the employee salaries and other expenditures and 

thus cannot participate in ASTM’s “consensus-based” process. For this rulemaking, 

ASTM is allowing public review, for no charge, of the ASTM test methods and draft 

work products relevant to this proposed rule at www.astm.org/epa. The EPA requests 

specific comments and supporting data on the substance of all of the test methods 

relevant to this rulemaking and specific comments on the ASTM process and ways to 

ameliorate the process concerns.

The ASTM methods E2779-10 “Standard Test Method for Determining 

Particulate Emissions from Pellet Heaters” and E2780-10 “Standard Test Method for 

Determining Particulate Emissions from Wood Heaters” are being considered for 

potentially replacing the wood heater fueling and operation requirements in Method 28 

for pellet heaters and wood heaters, respectively. Note that ASTM intends to use the 

same E2515-10 for the sampling and analysis portion for all the appliances and then 

separate methods per appliance types for the fueling and operation portions of these 

methods. The EPA believes that E2779-10 is a sound method for measuring emissions 

from pellet heaters/stoves and includes reasonable measures to reduce testing costs for

continuously-fed appliances, and we are proposing its use. However, because, as noted 
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earlier, some states were not able to participate in the ASTM method development 

process, we specifically request comments and supporting data of all aspects of not only

this test method but also all the proposed methods as part of the comments on this

proposed rule. 

Similarly, the EPA believes that ASTM Method E2780-10 includes improvements 

for testing adjustable and single burn rate wood heaters, and we are proposing many of 

the improvements today. For example, we are proposing the use of the E2780-10 

appendix for testing single burn rate appliances. However, we, and some states, do not 

agree with all the changes that ASTM has made for adjustable burn rate wood heaters, 

and some provisions are not as protective as we, and some states, now believe they need 

to be. As noted above, several states are concerned about how to best ensure that the 

methods are protective for the entire U.S., considering differences in wood species, 

density, and homeowner operation. The EPA and the states are particularly concerned 

about scenarios in which heaters/stoves will have higher emissions in homes than the 

emissions measured in the laboratories. For example, the states and the EPA are 

concerned about the ASTM changes on burn rate categories, i.e., easing or eliminating 

the lowest burn rates that often occur in home operations and are typically the dirtiest and 

least efficient. The EPA is asking for specific comments on these issues and 

recommendations and supporting data for other changes. The following paragraphs 

discuss some of the key test method provisions we are proposing and not proposing. 

Additional information on the methods is at www.epa.gov/burnwise, and at 

www.astm.org/epa. 

1. We do not agree with the ASTM changes to the burn rate categories, low burn
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rate requirement, and weightings in Method 28. Several states are very concerned that 

easing these items would create the potential for backsliding. Also, we are aware of 

several design changes being considered by a number of manufacturers that are relatively 

inexpensive and will reduce the emissions during periods when operated at low burn 

rates. We instead propose that the original provisions in Method 28 be retained for the 

burn rate categories and low burn rate requirement. We considered the weightings and 

believe that if weightings are to be used, they should be the same as the original 

requirements in Method 28. We are also proposing that the burn rates not be weighted at 

all for the “2019” standards but rather that the emission limits be separate for Burn Rate 

Category 1 (lowest burn rate category) and Burn Rate Category 4 (maximum burn rate 

category) and that compliance for each be shown separately. 

2. We propose to not allow 5 minutes for startup before closing the doors because 

startup is often the dirtiest part of the wood heater operation, and manufacturers need to 

ensure that startup emissions are also reduced. Again, relatively inexpensive means exist 

to reduce these emissions.

3. We are not proposing to use the new ASTM equation for converting the 

emission test values between the EPA Reference Method 5G “Determination of 

Particulate Emissions From Wood Heaters From a Dilution Tunnel Sampling Location” 

and the EPA Reference Method 5H “Determination of Particulate Emissions From Wood 

Heaters From a Stack Location” currently allowed in the NSPS. Rather, we are proposing 

that 5G(3) test values be reported as tested for heaters that have valid certifications prior 

to the effective date of this rule and ASTM E2515-10 for all other heaters and that 5H not 

be used for testing for certifications after the effective date of this rule. We request data 
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to help inform our decision for the final rulemaking.

4. We are not proposing to allow manufacturers to specify a smaller volume of 

the firebox for testing because of our concerns about how to ensure that homeowners do 

not circumvent such specification during operation, thereby increasing emissions beyond 

the levels that are measured during testing.

5. We are proposing several tighter specifications on the test fuel moisture 

content, fuel load and coal bed depth in order to improve the reproducibility and 

repeatability of the certification tests. This part of the proposal is based on 

recommendations from one of the original EPA-accredited laboratories. We specifically 

request comments and supporting data regarding the following proposed tighter 

specifications for the laboratory test: (a) tightening fuel load dry-basis moisture content 

tightened from the Method 28-allowed 6 percentage-point range from 19 percent to 25 

percent to a reduced range of 22.5 percent +/-1 percent; (b) tightening the Method 28-

allowed range for fuel load weight from 7.0 lb/ft3+/-10 percent of the fuel load weight (or 

7 lb/ ft3+/-0.7 lb/ft3) to 7 lb/ft3+/-1 percent (or 7 lb +/-0.07 lb) of the fuel load weight, 

calculated in accordance with Method 28; and (c) tightening the Method-28-allowed 

range for the test-initiation coal-bed weight from 20 percent to 25 percent of the fuel load 

weight to 22 percent +/-1 percent of the fuel load weight.

6. We propose to require efficiency testing according to CSA B415.1-1018 using 

the stack loss method. That is, during each test run, data must be obtained and presented 

for the purpose of calculation of overall efficiency as specified in CSA B415.1-10. This 

would include CO and carbon dioxide (CO2), flue gas temperature and appliance mass. 

 

18 “CSA B415.1-10: Performance testing of solid-fuel-burning heating appliances,” 

Canadian Standards Association, Mississauga, Ontario, Canada. 2010.
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CSA B415.1-10 was developed by a “consensus” process, but no states were part of the 

process. Thus, we specifically request comments on our proposal to require use of this 

method.

7. We propose that electronic test report submittals include the locked 

spreadsheets so the formulas used and relevant calculations can be evaluated in detail.

We request comments on this specific proposal.

8. We propose that the test report include a narrative detailing specifics about test 

conditions and operations, such as how the test was run, operating conditions, issues and 

special procedures.

9. We propose that each individual moisture content reading must be in the range 

of 18 to 28 percent on a dry basis and the average moisture content of each piece of test 

fuel must be in the range of 19 to 25 percent. Also, we propose the following procedure 

for the moisture measurements: “Using a fuel moisture meter as specified, determine the 

fuel moisture for each test fuel piece used for the test fuel load by averaging at least five 

fuel moisture meter readings, one from each of three sides, measured parallel to the wood 

grain. Penetration of the moisture meter insulated electrodes shall be 1⁄4 (one-fourth) the 

thickness of the fuel piece or 19 millimeters (mm) (3/4 in.), whichever is less, for 3 of the 

measurements made at approximately 3 inches from each end and the center. Two 

additional measurements at approximately one-third the thickness shall be made centered 

between the other three locations.”

10. We also propose this alternate procedure developed by Brookhaven National 
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Laboratory:

19 “Select three pieces of cord wood from the same batch of wood as the test 

fuel and the same weight as the average weight of the pieces in the test load ± 1.0 lb. 

From each of these three pieces, cut three slices. Each slice shall be 1⁄2” to 3⁄4” thick. One 

slice shall be cut across the center of the length of the piece. The other two slices shall be 

cut half way between the center and the end. Immediately measure the mass of each piece 

in pounds. Dry each slice in an oven at 220°F for 24 hours or until no further weight 

change occurs. The slices shall be arranged in the oven so as to provide separation 

between faces. Remove from the oven and measure the mass of each piece again as soon 

as practical in pounds. The moisture content of each slice, on a dry basis, shall be 

calculated as: 

MCslice = 100 ∙ (WSliceWet – WSliceDry) / WSliceDry

Where: WSliceWet = weight of the slice before drying in pounds; WSliceDry = weight of the 

slice after drying in pounds; [and] MCSlice = moisture content of the slice in % dry basis.”

11. We propose to require two Step 1 tests, one using crib wood and one using 

cord wood and reasonable additional non-binding tests with a range of fuels for which the 

appliance is designed for warranted and/or advertized operation. These tests are needed to 

show how emissions and efficiency vary according to test methods, operating scenarios, 

wood species and density and other variables such as cord wood versus crib wood. We 

believe that such testing would help assure consumers, neighbors and other stakeholders 

that the appliances perform as well on all manufacturer-listed fuels and operating 

 

19 “A Test Method for Certification of Cord Wood-Fired Hydronic Heating Appliances 

with Partial Thermal Storage: Measurement of Particulate Matter (PM) and Carbon 

Monoxide (CO) Emissions and Heating Efficiency of Wood-Fired Hydronic Heating 

Appliances with Partial Thermal Storage.” Prepared for NYSERDA by Brookhaven 

National Laboratory, February 15, 2013.
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scenarios as they do for the EPA laboratory test scenarios. Proposed Step 2 tests will use 

cord wood and not crib wood. The EPA, industry and states believe that moving to cord 

wood testing will help address concerns about actual emissions from heaters/stoves in 

homes versus test laboratories. We are working with states and industry on a cord wood 

test method and evaluating potential revisions to the current version of the ASTM E2780-

10 cord wood test method. Industry is conducting tests now using the cord wood test 

method, and we will consider the results of that testing when it becomes available, 

possibly as part of this rulemaking if these results become available in time to do so.

B. Central Heaters: Hydronic Heaters and Forced-Air Furnaces

The proposed subpart QQQQ would apply to new wood-fired residential hydronic 

heaters and forced-air furnaces and any other affected appliance as defined in subpart 

QQQQ as a “central heater.” We believe this new “central heater” categorization will 

better ensure that all appliances potentially affected under new proposed subpart QQQQ 

are included in this proposed action. The provisions of subpart QQQQ would apply to 

each affected unit that is manufactured or sold on or after [INSERT DATE 60 DAYS 

AFTER PUBLICATION OF THE FINAL RULE IN THE FEDERAL REGISTER].

This proposal does not include any requirements for heaters that are fueled solely by gas, 

oil or coal.

As discussed earlier in this preamble, subpart QQQQ affects a source category of 

mass-produced residential consumer products rather than typical industrial processes. 

Thus, this proposed NSPS has many aspects that are similar to those in Subpart AAA, 

e.g., certification of model lines and phased implementation. This Proposed Approach

would apply to all new residential hydronic heaters and forced-air furnaces. Under the 
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Proposed Approach, the Proposed Step 1 emission limit for residential hydronic heaters 

and forced air heaters would apply upon the effective date of the final rule, which we 

expect will be in 2014. The Proposed Step 2 emission limit for residential hydronic 

heaters and forced air heaters would apply 5 years after the effective date of the final rule. 

We ask for specific comments on the Proposed Approach and the degree to which these 

dates could be sooner.

We also considered an alternative three-step approach (Alternative Approach) for 

residential hydronic heaters and forced air heaters. Under this Alternative Approach, as in 

the Proposed Approach, the Alternative Step 1 emission limits for residential hydronic 

heaters and forced air heaters would apply upon the effective date of the final rule. The 

Alternative Step 2 emission limit for residential hydronic heaters and forced air heaters 

would apply 3 years after the effective date of the final rule. The Alternative Step 3 

emission limit for residential hydronic heaters and forced air heaters would apply 8 years 

after the effective date of the final rule (thus providing 5 years between the Alternative 

Step 2 and the Alternative Step 3). We ask for specific comments on this Alternative 

Approach and the degree to which these dates could be sooner.

Table 5 summarizes the proposed PM emissions standards that would apply under 

this Proposed Approach at each step. Table 6 summarizes the PM emissions standards 

that would apply under each step of the Alternative Approach. Similar to the proposed 

requirements for subpart AAA, we are not proposing a standard for CO or efficiency, but 

we are proposing to require manufacturers to collect and report CO emissions and 

efficiency data during certification tests.

Table 5. Proposed Approach Subpart QQQQ PM Emissions Standards
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Table 6. Alternative Approach Subpart QQQQ PM Emissions Standards

Appliance Steps21 Particulate Matter 

Emissions Limits

Residential 

Hydronic 

Heater

Step 1: 2014

(upon the 

effective date of 

the final rule) 

Step 2: 2017 

(3 years after the 

effective date of 

final rule)

Step 3: 2022 

(8 years after the 

effective date of 

the final rule)

0.32 lb/MMBtu heat 

output and a cap of 7.5 

g/hr for individual test 

runs

0.15 lb/MMBtu

0.06 lb/MMBtu

 

20 Based on the estimated publication of final rule in 2014. If the publication date 

changes, the EPA will change the dates based on the actual date of publication.

21 Based on the estimated publication of final rule in 2014. If the publication date 

changes, the EPA will change the dates based on the actual date of publication.

Appliance Steps20 Particulate Matter 

Emissions Limits

Residential 

Hydronic 

Heater

Step 1: 2014

(upon the 

effective date of 

the final rule) 

Step 2: 2019 

(5 years after the 

effective date of 

final rule)

0.32 lb/MMBtu heat 

output and a cap of 7.5 

g/hr for individual test 

runs

0.06 lb/MMBtu

Forced-Air 

Furnace

Step 1: 2014

(upon the 

effective date of 

the final rule) 

Step 2: 2019 

(5 years after the 

effective date of 

final rule)

0.93 lb/MMBtu

0.06 lb/MMBtu
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Forced-Air 

Furnace

Step 1: 2014

(upon the 

effective date of 

the final rule) 

Step 2: 2017 

(3 years after the 

effective date of 

final rule)

Step 3: 2022 

(8 years after the 

effective date of 

final rule)

0.93 lb/MMBtu

0.15 lb/MMBtu

0.06 lb/MMBtu

Unlike the current subpart AAA requirements, the subpart QQQQ requirements 

would not provide an additional time period for the sale of unsold units manufactured 

before the compliance date. The subpart QQQQ requirements would not include a small 

volume manufacturer compliance extension. See section V.C. of this preamble for more 

discussion of this topic. We ask for comments on the timing for implementation.

As in the current subpart AAA for wood heaters/stoves, we are proposing a list of 

prohibited fuels because their use would cause poor combustion or even hazardous 

conditions. We request comment on these requirements and data to support additional 

requirements, if warranted. Also, as in the current subpart AAA for wood heaters/stoves,

we are proposing that the owner or operator must not operate the hydronic heater or 

forced-air furnace in a manner that is inconsistent with the owner’s manual. For pelletfueled appliances, this proposal makes it clear that operation according to the owner’s 

manual includes operation only with pellet fuels that have been used in the certification 

test and have been graded and marked under a licensing agreement with the PFI, or 

equivalent (after request and subsequent approval by the EPA), to meet certain minimum 
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requirements and procedures for a quality assurance process. Details of the PFI program 

are available at http://pelletheat.org/pfi-standards/pfi-standards-program/. We believe that 

these provisions are necessary to ensure that the appliances operate properly such that 

emissions are reduced as intended. We ask for specific comments on the use of the PFI 

program and the PFI specifications, especially the degree to which the PFI program will 

adequately ensure the absence of construction and demolition waste (and associated toxic 

contaminants) in the pellets. 

The proposed labeling requirements and owner’s manual requirements are similar 

to the guidelines in the EPA’s current voluntary hydronic heater program with some 

improvements. We request specific comments on ways to improve the delivery of 

information on the permanent label and in the owner’s manual and whether different 

information might be useful to the consumer and to the regulatory authorities.

The structure of the rest of the proposed subpart QQQQ is similar to the proposed 

subpart AAA certification and quality assurance process. We request specific comments

on changes or improvements to that process that might be needed to address any special 

concerns related to the certification of hydronic heaters and forced-air furnaces.

As discussed earlier, the EPA developed Method 28 OWHH, in 2006, as part of 

our efforts for voluntary qualification of cleaner hydronic heaters. We received input at 

that time from manufacturers, laboratories, and some states in order to quickly develop a 

mostly consensus-based method that we incorporated into the program partnership 

agreements. We used Method 28 for wood heaters/stoves as the foundation. Thus,

Method 28 OWHH has many aspects similar to Method 28. Three significant differences 

are: (1) Method 28 OWHH uses larger cribs because hydronic heater fireboxes are 
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typically much larger than wood heater fireboxes; (2) Method 28 OWHH uses red oak 

instead of Douglas fir because red oak is the more common fuel in the U.S.; and (3) 

Method 28 OWHH includes procedures for determining 8-hour heat output and 

efficiency. The manufacturers, laboratories, states and the EPA have now had over 7

years of experience with Method 28 OWHH and its successor Method 28 WHH 

(improved and expanded to include indoor heaters, not just outdoor heaters).

All the stakeholders that have provided input on the test methods agree that the 

methods should be thoroughly vetted and changed as necessary to improve the method’s 

accuracy and precision and to address concerns about how to best ensure protection 

across the entire U.S. when various operating scenarios and wood species and densities 

are used. ASTM has developed E2618-09 to address some of these concerns, and the 

EPA believes that E2618-09 does include some improvements. However, as with the 

wood heater/stove methods, we and some states do not agree with all the changes that 

ASTM has made. For example, the states of Washington and Oregon are very concerned 

that Method 28 WHH and ASTM E2618-09 do not specify fueling with Douglas Fir,

which is used in EPA Method 28 for wood heaters/stoves and which these states require 

in their regulations for residential wood heaters, including hydronic heaters. They are 

concerned that hydronic heaters tested with Red Oak will have higher emissions when 

fueled with Douglas Fir and other less dense species typical in their states. Also, a 

number of states and the EPA are concerned about the ASTM changes to the burn rate 

categories, i.e., easing or eliminating testing at the lowest burn rates, which often occur in 

home operations and are typically the dirtiest and least efficient. For several years, we 

have been communicating with European certification laboratories to learn how they
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conduct their tests under EN 303-5 and to consider if incorporating some of their testing 

procedures might improve our test methods.

More recently, because of initial concerns about some surprisingly high 

laboratory test efficiencies for a couple of the EPA voluntary partnership program Phase 

2 qualified partial heat storage models, the EPA, the Northeast states that regulate 

hydronic heaters, laboratories (including EPA-accredited laboratories and Brookhaven 

National Laboratory) and manufacturers have conducted an exhaustive review of 

voluntary partnership program qualifying test reports. All of the stakeholders that 

provided input on the test methods agree that we need a change in the test method for 

testing of non-integral partial heat storage models (i.e., models that have separate heat 

storage but the storage does not have the capacity to safely handle all the heat generated 

by a full load of fuel). ASTM has been leading an effort to develop an Appendix X2 to 

the test method for such models but has not completed that effort as of this proposal.

Brookhaven National Laboratory has recommended a method to the New York State 

Department of Environmental Conservation (NYSDEC) and NYSDEC has proposed that 

method be used for certification of such models in their states. We are proposing that 

method be used for certification of the NSPS for hydronic heaters equipped with a partial 

heat storage unit.22 

Further, we are proposing revisions to Method 28 WHH that would require that 

all affected non-pellet hydronic heaters, subject to new subpart QQQQ, conduct 

certification compliance testing using both crib wood and cord wood for the 2014 

emission limits and solely cord wood for the 2019 emission limits.

 

22 See footnote 19.
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Thus, we are asking for specific comments on whether the EPA should use: (1) 

one or more of the draft versions of Appendix X2 being considered as part of ASTM 

work product WK26581; (2) the European Union test method EN303-05 as the Maine 

Department of Environmental Protection has recently approved for certification of 

hydronic heaters in their state as equivalent to the EPA Method 28 WHH; (3) the use of 

the proposed new partial thermal storage test method (developed by Brookhaven National 

Laboratory); and/or (4) some other test method. For use of any of the test methods, the 

EPA would require that the amount of heat storage for the actual sale and installation of 

the hydronic heaters be no less than the amount used for the certification tests. Because 

EN303-05 does not currently use heat storage during the certification test, if the EPA 

were to use EN303-05 test results, the EPA would require the installed heater to have 

heat storage that can safely handle at least 60 percent of the maximum heat output of the 

heater or a greater level if the manufacturer specifies a greater level. The EPA is asking 

for specific comments on the appropriateness of this heat storage level or other levels.

The EPA will consider any or all of these options as the preferred reference test methods 

or as acceptable emission testing alternatives. (ASTM previously developed an Appendix 

X1 for testing of models that have “full” heat storage that can safely accept the heat from 

the full load of fuel.) We request comments on all aspects of heater testing and are 

especially interested in emission test data that compare the results for testing by these 

different methods.

Also, the exhaustive review discussed above found a number of areas in the 

methods to improve the quality of the data and reduce anomalies. In June 2011, the 

voluntary partnership program stakeholders agreed to a number of changes to Method 28 
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OWHH, and we are proposing the revised method as EPA Reference Method 28 WHH. 

The EPA is asking for specific comments on this method and recommendations and 

supporting data for other changes or acceptable alternatives. The following paragraphs 

discuss some of the key changes we are proposing for comment. Additional information 

on the EPA methods is available at www.epa.gov/burnwise. The ASTM methods and 

draft work products are available at www.astm.org/epa.

1. Heater (aka Boiler) temperature range

We propose that for all tests, the return water temperature to the heater must be 

120°F or greater. We additionally propose that if the manufacturer specifies a thermal 

control valve or other arrangement to be installed and set to control the return 

temperature at 120°F or higher, the valve must be installed and set per the manufacturer’s 

written instructions.

2. Efficiency calculations

We propose to require the use of thermopiles to measure the temperature change 

“delta T” and verify accuracy of the load side flow meter. The accuracy of the flow meter 

is determined separately by direct weighing of timed water collection. Thermocouples 

must measure water temperature at the inlet and outlet of the load side heat exchanger. 

We propose to delete the requirement for supply side flow measurements and require one 

load side reading with thermopiles (using a commercial system or a homemade system). 

Efficiency would be measured on the output (load) side of the heat exchanger. The flow 

meter would be calibrated before and after each test run within the flow range used for 

the test. 

3. Time period for recording temperatures
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We propose that all water temperatures, differential water temperatures and water 

flow rates must be recorded at time intervals of 1 minute or less. This data file must be 

submitted with the test report. For determination of heat output, the data for these

parameters must be measured in equal time intervals no greater than 10 minutes or at a 

frequency that results in a minimum of 50 equal intervals per test run, whichever is 

greater.

4. Test fuel moisture content 

We propose that each individual test fuel moisture content reading must be in the 

range of 18 to 28 percent on a dry basis and the average moisture content of each piece of 

test fuel must be in the range of 19 to 25 percent.

We also propose the following moisture measurement procedure: Using a fuel 

moisture meter as specified in the test method, determine the fuel moisture for each test 

fuel piece used for the test fuel load by averaging at least five fuel moisture meter 

readings, one from each of three sides, measured parallel to the wood grain. Penetration 

of the moisture meter insulated electrodes must be one-fourth the thickness of the fuel 

piece or 19 mm (3/4 in.), whichever is less for three of the measurements made at 

approximately 3 inches from each end and the center. Two additional measurements at 

approximately one-third the thickness shall be made centered between the other three 

locations. We request specific comments on the moisture content limits and the 

procedures for determining the moisture content and the typical variances due to the 

measurement procedures.

We also request specific comments on the following approach for determining 

moisture content. “Select three pieces of cord wood from the same batch of wood as the 
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test fuel and the same weight as the average weight of the pieces in the test load ± 1.0 lb. 

From each of these three pieces, cut three slices. Each slice shall be 1⁄2” to 3⁄4” thick. One 

slice shall be cut across the center of the length of the piece. The other two slices shall be 

cut half way between the center and the end. Immediately measure the mass of each piece 

in pounds. Dry each slice in an oven at 220°F for 24 hours or until no further weight 

change occurs. The slices shall be arranged in the oven so as to provide separation 

between faces. Remove from the oven and measure the mass of each piece again as soon 

as practical in pounds. The moisture content of each slice, on a dry basis shall be 

calculated as: 

MCslice = 100 ∙ (WSliceWet – WSliceDry) / WSliceDry

Where: WSliceWet = weight of the slice before drying in pounds; WSliceDry = weight of the 

slice after drying in pounds; [and] MCSlice = moisture content of the slice in % dry

basis.”23

Also, we propose that moisture must not be added to previously dried fuel pieces 

except by storage under high humidity conditions and temperature up to 100oF. Fuel 

moisture must be measured no more than 4 hours before using the fuel for a test. The test 

report must describe the source and storage history of the test fuel.

5. Water density

a. We propose that the measured volumetric flow from the flow meter be 

converted to mass basis by using the water density based on water temperature. The same 

method must be used on both the load and supply side if the optional supply side meter is 

used.

 

23 See footnote 19.
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b. We propose that the water density be calculated using the water temperature 

measured at the flow meter. 

6. Calculations

a. We propose that the electronic test reports submittals include all data within 

the locked spreadsheets so the formulas used and relevant calculations can be reviewed in 

detail. 

b. To ensure common application, we propose to require averages to be 

calculated on each 10-minute reading rather than averaging over the entire test run.

7. Overall efficiency (CSA B415.1-10 Stack Loss Method)

We propose that during each test run, data must be obtained and presented for the 

purpose of calculation of overall efficiency as specified in the stack loss method in CSA 

B415.1-10. This includes CO and CO2, flue gas temperature, and appliance mass

(remaining fuel weight). Overall efficiency for each run must be determined as per CSA 

B415.1-10 and reported. Whenever the CSA B415.1-10 overall efficiency is found to be 

lower than the overall efficiency based on the load side measurements, as determined by 

this method, the report must include a discussion of the reasons for this result.

8. Wood loading 

Test fuel loads would be determined by multiplying the firebox volume by 4.54 

kg (10 lb) of wood (as used, wet weight) per cubic foot, or a higher load density as 

recommended by the manufacturer’s operating instructions. As discussed earlier, the EPA

will require separate tests in the proposed Step 1 using cribs and using cord wood. In the 

proposed Step 2, the tests would all be using cord wood. There are ongoing discussions 

on how to improve both types of tests. We are working with states and industry on a cord 
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wood test method and evaluating making revisions to the current version of the ASTM 

cord wood test method and states’ ideas on cord wood testing. Also, we are reviewing 

European experiences with cord wood testing.

9. Drawing of test apparatus 

The test report would be required to contain a drawing of the test apparatus, 

including thermocouples, piping arrangements including any recirculation loops, the 

thermopile and flow meter(s).

10. Aquastat settings

Aquastat or other heater output control device settings that are adjustable would 

be set using manufacturer specifications, either as factory set or in accordance with the 

owner’s manual, and must remain the same for all burn categories.

11. Narrative

The test report would be required to include a statement that the test was 

conducted according to the method specified. If there are any deviations from the test 

procedure requirements, the test report would need to include a section identifying those 

deviations, the reasons for those deviations, and an evaluation of the data quality

implications, if any, of such deviations on the test results.

12. The test report would include a standard summary page as a quick check for 

the reviewer that results are within method specifications.

13. We propose to require testing with a range of all fuels for which the 

appliance is designed, per the manufacturer’s warranty and owner’s manual, to show how 

emissions and efficiency vary according to species and density and cord wood versus crib

wood.
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The EPA is proposing to rely on the test method that has been developed by the 

CSA for forced-air furnaces. All CSA standards are developed through a consensus 

development process approved by the Standards Council of Canada. This process brings 

together volunteers representing varied viewpoints and interests to achieve consensus and 

develop a standard. CSA worked for years on development of this test method that has its 

roots in earlier U.S. efforts on wood heaters/stoves. The current version of CSA B415.1-

10 was published in March 2010, and it includes not only the forced-air furnace test 

method but also new Canadian emission performance specifications for indoor and 

outdoor central heating appliances.

Although the CSA B415.1-10 technical committee included 32 individuals, 

including numerous U.S. manufacturers and laboratories, it did not include any states or 

environmental groups, and the EPA participation was minimal. Nevertheless, we are 

satisfied that this CSA method warrants proposal for this rulemaking. We request specific 

comments and supporting data. We ask for specific comments on the appropriateness of 

using the CSA test method in its entirety, including the use of cord wood instead of crib

wood that are used in current versions of Method 28 and Method 28 WHH. To review the 

CSA test method, please go to www.csa.ca.

C. Masonry Heaters

The proposed subpart RRRR would apply to new residential masonry heaters. The 

provisions apply to each affected unit that is manufactured on or after [INSERT DATE 

60 DAYS AFTER PUBLICATION OF THE FINAL RULE IN THE FEDERAL 

REGISTER]. We are proposing that, as of the effective date of the final rule, no person 

would manufacture or sell a residential masonry heater that does not meet the proposed 
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emission limit of 0.32 lb of PM per MMBtu heat output. We are also proposing a 5-year 

small volume manufacturer compliance extension that would apply to companies that 

construct fewer than 15 masonry heaters per year. See section V.C. of this preamble for 

more discussion of compliance date related issues. We request specific comments on the 

degree to which these dates can be sooner. As in the case of the other proposed standards, 

we are proposing requirements that would apply to the operator of the masonry heater, 

including a provision to operate the unit in compliance with the owner’s manual; a 

prohibition on use of certain fuels; and a requirement to use licensed wood pellets or 

equivalent, if applicable. We are not proposing efficiency or CO standards for new 

residential masonry heaters at this time because data are not yet available to support the 

basis for such standards. 

The EPA is proposing to rely on ASTM method E2817-11 for masonry heaters. 

The laboratories, some states and the masonry heater industry worked for years on drafts 

of this method that has its roots in earlier regulatory efforts in Colorado. The EPA has 

participated in the discussions from time to time over the years and has provided 

comments and suggestions. There have been a number of variations of similar methods 

over the years. The current ASTM methods are ASTM E2817-11 “Standard Test Method 

for Test Fueling Masonry Heaters” and the draft work product ASTM WK26558 

“Specification for Calculation Method for Custom Designed, Site-built Masonry

Heaters.” (http://www.astm.org/DATABASE.CART/WORKITEMS/WK26558.htm.) We 

are encouraged by the progress shown by development of the ASTM method and the

current draft work product and propose that they be used for this rulemaking. We request 

specific comments on these methods and any changes that should be considered and 
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supporting data for those changes. We request specific comments and supporting 

emission test data on the use of “Annex A1. Cordwood Fuel” and “Annex A2. Cribwood 

Fueling.” ASTM is allowing public review, for no charge, of the ASTM test methods and 

draft work products relevant to this rule at www.astm.org/epa.

As an alternative to testing, we are proposing that manufacturers of masonry

heaters may choose to submit a computer model simulation program, such as ASTM WK 

26558 noted above, for the EPA’s review and approval. 

The structure of the rest of the proposed new subpart RRRR is similar to the 

proposed subpart AAA certification and quality assurance process and contains similar 

requirements for labels, owner’s manual, etc. One difference, however, is that for small 

custom unit manufacturers, we are requiring less stringent quality control (QC)

procedures. Specifically, we are proposing that the initial certification for these custom 

units is sufficient and that no further QC is necessary since each unit is a unique model 

and subject to certification. We request comment on changes or improvements that might 

be needed to address special concerns related to certification of masonry heaters.

IV. Summary of Environmental, Cost, Economic, and Non-Air Health and 

Energy Impacts

The EPA estimates the proposed NSPS’s total annualized average nationwide 

costs would be $15.7 million ($2010) over the 2014 through 2022 period. The economic 

impacts for industries affected by this proposed rule over this same period range from 

4.3 percent for manufacture of wood heater/stove models to as much as an 6.4 percent 

compliance cost-to-sales estimate for manufacture of single burn rate wood heater

models. These impacts do not presume any pass-through of impacts to consumers. With 
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pass-through to consumers, these impact estimates to manufacturers will decline 

proportionate to the degree of pass-through.

A. What are the air quality impacts? 

To determine the air quality impacts, we developed emission factors for each 

appliance type and then applied those emission factors to shipment data for each of the 

appliance types subject to the proposed NSPS.24 We developed the emission factors using 

the EPA Residential Wood Combustion (RWC) emission estimation tool,

25 which is a 

Microsoft Access database that compiles nationwide RWC emissions using county-level, 

process-specific data and calculations. The compilation of such data is a large, important, 

continually improving effort by the EPA and the states to ensure that we and the states 

have access to the best information available. We summed the estimated nationwide 

number of appliances and the estimated total tons of wood burned for each of the relevant 

product categories in the inventory and then made some adjustments/assumptions to the 

baseline RWC inventory to reflect emission characteristics specific to new units.

We used the resulting subset of the RWC database to calculate an average 

emission rate per appliance for each category, as follows. First, we multiplied the total 

tons of wood burned by devices within the category by the category emission factor to 

calculate the total tons of emissions for each of the pollutants PM2.5, volatile organic 

compound (VOC), and CO emissions for that category. Then we divided these values by

the number of appliances in the category to calculate the average emissions of PM2.5, 

VOC and CO per individual appliance. We then developed adjusted emission factors to 

 

24 Memo to Gil Wood, USEPA, from EC/R, Inc. Estimated Emissions from Wood 

Heaters. February 15, 2013.

25 rwc_2008_tToolv4.1_feb09_2010.zip available in the docket.
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reflect the NSPS options and then used the adjusted factors to calculate average tons of 

emissions of each of these three pollutants per appliance for each category.

We used data in the Frost & Sullivan Market (F&S) report26 on 2008 shipments 

by product category and F&S revenue forecasts, which incorporated the weak economy

in years 2009 and 2010, to calculate the reduced number of shipments in years 2009 and 

2010. We adjusted these data to include appliances not covered in the F&S report (e.g., 

forced-air furnaces). For years 2011 through 2038, we estimated shipments based on a 

forecasted revenue growth rate of 2.0 percent, in keeping with the average annual growth 

in real gross domestic product (GDP) predicted by the U.S. Bureau of Economic 

Analysis.27 There is not a perfect correlation between shipments and revenue (for 

example, because of their higher unit cost, pellet heaters/stoves generate more absolute 

revenue than wood heaters/stoves), but we think the overall trend in the projection is 

reasonable in the absence of specific shipment projections. 

The next step was to calculate the total emissions per appliance category. First, 

we multiplied the emission factor for each category by the inventory value of total tons of 

wood burned by all appliances within that category, and then divided by the number of 

appliances in the inventory population. The appliance value was then multiplied by the 

number of units shipped to calculate total emissions from each category per year using 

the baseline conditions emission factors (i.e., in the absence of a revised NSPS). Using 

 

26 Market Research and Report on North American Residential Wood Heaters, 

Fireplaces, and Hearth Heating Products Market. Prepared by Frost & Sullivan. April 26, 

2010, pp. 31-32.

27 2013 Global Outlook projections prepared by the Conference Board in November 

2012; http://www.conference-board.org/data/globaloutlook.cfm.
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the same procedure, category emissions were then calculated using the emission factors 

for the proposed NSPS.

Table 7 is a summary of the average emissions reductions over years 2014 

through 2022 resulting from implementing the proposed NSPS compared to baseline 

conditions. Note that we do not have emission impacts from masonry heaters because 

they are not included in the RWC emission estimation tool. However, we believe that 

nationwide emissions from masonry heaters are relatively low, given the low number of 

sales. Thus, we also believe that the emission reductions from these sources will be 

relatively low.
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Table 7. Estimated Annual Average (2014-2022) Air Quality Impacts28

Appliance 

Type

PM2.5 (tons) VOC (tons) CO (tons)

Baseline

Revised 

NSPS

Emission 

Reduction Baseline

Revised 

NSPS

Emission 

Reduction Baseline

Revised 

NSPS

Emission 

Reduction

Wood Heaters 548 385 163 781 551 230 7,857 5,448 2,409

Single Burn 

Rate Heaters 932 178 754 1,614 244 1,370 7,029 2,860 4,169

Pellet 

Heaters/Stoves 199 150 49 3 2 1 1,035 778 257

Furnace: 

Indoor, Cord 

wood 3,044 434 2,610 1,290 184 1,106 20,294 2,896 17,398

Hydronic 

Heating 

Systems 1,332 84 1,249 565 35 530 8,883 557 8,326

Total 6,055 1,230 4,825 4,253 1,016 3,237 45,098 12,538 32,559

Note: This table does not include the emissions that continue for the duration of the lifetime of the appliance’s use, typically

greater than 20 years.

 

28 See footnote 24.
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B. What are the benefits?

Emission reductions associated with the requirements of this rule will generate 

health benefits by reducing emissions of PM2.5, HAP, as well as criteria pollutants and 

their precursors, including CO and VOC. VOC are precursors to PM2.5 and ozone. For 

this rule, we were only able to quantify the health co-benefits associated with reduced 

exposure to PM2.5 from directly emitted PM2.5. Our benefits reflect the average of annual 

PM2.5 emission reductions occurring between 2014 and 2022 (inclusive). We estimate the 

monetized PM2.5 -related health benefits of the proposed residential wood heaters NSPS 

in the 2014-2022 timeframe to be $1,800 million to $4,100 million (2010 dollars) at a 3-

percent discount rate and $1,700 million to $3,700 million (2010 dollars) at a 7-percent 

discount rate. Using alternate relationships between PM2.5 and premature mortality 

supplied by experts, higher and lower benefits estimates are plausible, but most of the 

expert-based estimates fall between these two estimates.29 A summary of the emission 

reduction and monetized benefits estimates for this rule at discount rates of 3 percent and 

7 percent is in Table 8 of this preamble.

Table 8. Summary of Monetized PM2.5-related Health Benefits for Proposed Residential 

Wood Heaters NSPS in 2014-2022 Timeframe (millions of 2010 dollars)a, b

Pollutant

Estimated Emission 

Reductions

(tpy)

Total Monetized 

Benefits

(3% Discount Rate)

Total Monetized Benefits

(7% Discount Rate)

Directly 

emitted 

PM2.5

4,825 $1,800 to $4,200 $1,700 to $3,700

PM2.5Precursors

VOC 3,250 -- --

 

29 Roman, et al, 2008. “Expert Judgment Assessment of the Mortality Impact of Changes 

in Ambient Fine Particulate Matter in the U.S.,” Environ. Sci. Technol., 42, 7, 2268 –

2274.
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a All estimates are for the 2014-2022 timeframe (inclusive) and are rounded to two 

significant figures so numbers may not sum across rows. The total monetized benefits 

reflect the human health benefits associated with reducing exposure to PM2.5 through 

reductions of PM2.5 precursors, such as NOX, and directly emitted PM2.5. It is important to 

note that the monetized benefits do not include reduced health effects from exposure to 

HAP, direct exposure to NO2, exposure to ozone, VOC, ecosystem effects or visibility

impairment. 

b

PM benefits are shown as a range from Krewski, et al. (2009) to Lepeule, et al. (2012). 

These models assume that all fine particles, regardless of their chemical composition, are 

equally potent in causing premature mortality because the scientific evidence is not yet 

sufficient to allow differentiation of effects estimates by particle type.

These benefits estimates represent the total monetized human health benefits for 

populations exposed to less PM2.5 from emission limits established to reduce air 

pollutants in order to meet this rule. Due to analytical limitations, it was not possible to 

conduct air quality modeling for this rule. Instead, we used a “benefit-per-ton” approach 

to estimate the benefits of this rulemaking. To create the benefit-per-ton estimates, this 

approach uses a model to convert emissions of PM2.5 precursors into changes in ambient 

PM2.5 levels and another model to estimate the changes in human health associated with 

that change in air quality, which are then divided by the emissions in specific sectors. 

These benefit-per-ton estimates were derived using the approach published in Fann et al. 

(2012),30 but they have since been updated to reflect these studies and population data in 

the 2012 PM NAAQS RIA.31 Specifically, we multiplied the benefit-per-ton estimates 

from the “Residential Wood Heaters” category by the corresponding emission 

 

30 Fann, N., K.R. Baker, and C.M. Fulcher. 2012. “Characterizing the PM2.5-related 

health benefits of emission reductions for 17 industrial, area and mobile emission sectors 

across the U.S.” Environment International 49 41–151.

31 U.S. Environmental Protection Agency (U.S. EPA). Regulatory Impact Analysis for the 

Final Revisions to the National Ambient Air Quality Standards for Particulate Matter. 

EPA-452/R-12-003. Office of Air Quality Planning and Standards, Health and 

Environmental Impacts Division. December 2012. Available at 

http://www.epa.gov/pm/2012/finalria.pdf.
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reductions.32 All national-average benefit-per-ton estimates reflect the geographic 

distribution of the modeled emissions, which may not exactly match the emission 

reductions in this rulemaking, and thus they may not reflect the local variability in 

population density, meteorology, exposure, baseline health incidence rates, or other local 

factors for any specific location. More information regarding the derivation of the 

benefit-per-ton estimates for this category is available in the technical support document, 

which is available in the docket. 

These models assume that all fine particles, regardless of their chemical 

composition, are equally potent in causing premature mortality because the scientific 

evidence is not yet sufficient to allow differentiation of effects estimates by particle type. 

Even though we assume that all fine particles have equivalent health effects, the benefitper-ton estimates vary between precursors depending on the location and magnitude of 

their impact on PM2.5 levels, which drive population exposure. 

It is important to note that the magnitude of the PM2.5 benefits is largely driven by 

the concentration response function for premature mortality. We cite two key empirical 

studies, one based on the American Cancer Society cohort study33 and the extended Six 

Cities cohort study.

34 In the Regulatory Impact Analysis (RIA) for this rule, which is 

 

32 U.S. Environmental Protection Agency. Technical support document: Estimating the 

benefit per ton of reducing PM2.5 precursors from 17 sectors. Research Triangle Park, 

NC. January 2013.

33 Krewski, C.A., III, R.T. Burnett, M.J. Thun, E.E. Calle, D. Krewski, K. Ito, and G.D. 

Thurston. 2002. “Lung Cancer, Cardiopulmonary Mortality, and Long-term Exposure to 

Fine Particulate Air Pollution.” Journal of the American Medical Association 287:1132-

1141.

34 Lepeule J, Laden F, Dockery D, Schwartz J 2012. “Chronic Exposure to Fine Particles 

and Mortality: An Extended Follow-Up of the Harvard Six Cities Study from 1974 to 

2009.” Environ Health Perspect. Jul;120(7):965-70.
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available in the docket, we also include benefits estimates derived from expert judgments 

(Roman et al, 2008) as a characterization of uncertainty regarding the PM2.5-mortality

relationship. 

Considering a substantial body of published scientific literature, reflecting

thousands of epidemiology, toxicology, and clinical studies, the EPA’s Integrated 

Science Assessment for Particulate Matter35 documents the association between elevated 

PM2.5 concentrations and adverse health effects, including increased premature mortality. 

This assessment, which was reviewed twice by the EPA’s independent Science Advisory

Board, concluded that the scientific literature consistently finds that a no-threshold model 

most adequately portrays the PM-mortality concentration-response relationship. 

Therefore, in this analysis, the EPA assumes that the health impact function for fine 

particles is without a threshold. 

In general, we are more confident in the magnitude of the risks we estimate from 

simulated PM2.5 concentrations that coincide with the bulk of the observed PM 

concentrations in the epidemiological studies that are used to estimate the benefits. 

Likewise, we are less confident in the risk we estimate from simulated PM2.5

concentrations that fall below the bulk of the observed data in these studies. 

Concentration benchmark analyses (e.g., lowest measured level [LML] or one standard 

deviation below the mean of the air quality data in the study) allow readers to determine 

the portion of population exposed to annual mean PM2.5 levels at or above different 

 

35 U.S. Environmental Protection Agency (U.S. EPA). 2009. Integrated Science 

Assessment for Particulate Matter (Final Report). EPA-600-R-08-139F. National Center 

for Environmental Assessment – RTP Division. December. Available on the Internet at 

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=216546.
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concentrations, which provides some insight into the level of uncertainty in the estimated 

PM2.5 mortality benefits. There are uncertainties inherent in identifying any particular 

point at which our confidence in reported associations becomes appreciably less, and the 

scientific evidence provides no clear dividing line. However, the EPA does not view 

these concentration benchmarks as a concentration threshold below which we would not 

quantify health benefits of air quality improvements. 

For this analysis, policy-specific air quality data are not available due to time or 

resource limitations. Thus, we are unable to estimate the percentage of premature 

mortality associated with this specific rule’s emission reductions at each PM2.5 level. As a

surrogate measure of mortality impacts, we provide the percentage of the population 

exposed at each PM2.5 level using the source apportionment modeling used to calculate 

the benefit-per-ton estimates for this sector. Using the Krewski, et al, (2009) study, 93 

percent of the population is exposed to annual mean PM2.5 levels at or above the LML of 

5.8 μg/m3. Using the Lepeule, et al, (2012) study, 67 percent of the population is exposed 

above the LML of 8 μg/m3. It is important to note that baseline exposure is only one 

parameter in the health impact function, along with baseline incidence rates, population, 

and change in air quality. Therefore, caution is warranted when interpreting the LML

assessment for this rule because these results are not consistent with results from rules 

that had air quality modeling. 

Every benefit analysis examining the potential effects of a change in 

environmental protection requirements is limited, to some extent, by data gaps, model 

capabilities (such as geographic coverage) and uncertainties in the underlying scientific 

and economic studies used to configure the benefit and cost models. Despite these 
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uncertainties, we believe the benefit analysis for this rule provides a reasonable indication 

of the expected health benefits of the rulemaking under a set of reasonable assumptions. 

In addition, we have not conducted air quality modeling for this rule, and using a benefitper-ton approach adds another important source of uncertainty to the benefits estimates. 

The 2012 PM2.5 NAAQS benefits analysis provides an indication of the sensitivity of our 

results to various assumptions. 

One should note that the monetized benefits estimates provided above do not 

include benefits from several important benefit categories, including exposure to HAP, 

VOC and ozone exposure, as well as ecosystem effects and visibility impairment. 

Although we do not have sufficient information or modeling available to provide 

monetized estimates for this rule, we include a qualitative assessment of these 

unquantified benefits in the RIA36 for this proposal.

For more information on the benefits analysis, please refer to the RIA for this 

rule, which is available in the docket.

C. What are the cost impacts? 

In analyzing the potential cost impacts of the proposed NSPS, we considered two 

types of impacts. The first was the impact to the manufacturer to comply with the 

proposed standards. The second was the increase in price of the affected unit. In both of 

these cases, we considered the same input variables: R&D cost to develop and certify

complying model lines, certification costs (where these are separate from R&D), 

reporting and recordkeeping costs, numbers of shipments of each appliance category

(modified, from Frost & Sullivan report), number of manufacturers, and number of 

 

36 Regulatory Impact Analysis (RIA) for Residential Wood Heaters NSPS. [INSERT 

DATE RULE IS SIGNED].
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models per manufacturer. This section of the preamble contains a summary of these 

costs. For more detailed information, see the manufacturer cost impact memo37 and unit 

cost memo38 in the docket. Unless otherwise specified, all costs are in 2010 dollars.

To develop average R&D costs, we reviewed information provided by 

manufacturers. Based on this information, we conservatively

39 estimated average costs to 

develop a new model line, including testing, of $356,250 for certified wood heaters and 

pellet heaters/stoves. We also assumed $356,250 for single burn rate wood heaters, which 

may be high if currently available units can meet the standards without significant 

modifications as some manufacturers have suggested. We also assumed development 

costs for forced-air furnaces and hydronic heaters of $356,250 because of the 

conservative nature of this estimate. Finally, we also conservatively assumed 

development costs of $356,250 for the masonry heaters, even though an estimate of 

$250,000 was provided by a manufacturer who is the current chair of the HPBA Masonry

Heater Caucus and President of the Alliance of Masonry Heater and Oven Professionals. 

The estimates of the cost of R&D are crucial to our estimates of overall costs and 

economic impacts and greatly influence our decisions on BSER, compliance lead times 

and small volume provisions. Thus, we request specific comments on these estimates, 

including whether they should be reduced and thus allow greater emission reductions 

sooner.

 

37 Memo to Gil Wood, USEPA, from EC/R, Inc. Residential Heater Manufacturer Cost 

Impacts. February 22, 2013.

38 Memo to Gil Wood, USEPA, from EC/R, Inc. Unit Cost Estimates of Residential 

Wood Heating Appliances. February 21, 2013.

39 In developing average R&D costs, the EPA used the highest industry R&D estimates 

supplied, erred on the side of over-estimating when we had to estimate additional costs 

(e.g., testing with cord wood in addition to crib wood) and overstated the number of 

model lines that would undergo R&D nationwide.
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We annualized the R&D costs, applied the NSPS implementation assumptions, 

and estimated the average manufacturing cost per model line per manufacturer. Under the 

proposed rules, pellet heaters/stoves will face certification (testing) costs only (no R&D 

should be required), so we estimated certification costs of $10,000 per model line. 

Similarly, some masonry heater model lines that would comply with the proposed 

standards have already been developed. These manufacturers would also face 

certification costs of $10,000 per model line. We estimated post R&D period certification 

costs for hydronic heaters and forced-air furnaces at $20,000 per model line.

The masonry heater compliance costs included implementation of a software 

package based on a European masonry heater design standard. This software has been 

verified in the laboratory and under field conditions to produce masonry heaters that 

would meet the proposed NSPS emission limits. The cost of this software to the user is 

approximately $1,500 for the package with an approximately $450 annual fee that 

commences in the second year following purchase. In addition, we believe that some 

manufacturers will use this approach to demonstrate that “similar” model designs meet 

the proposed emissions standards.

The estimate of the number of model types was derived from information 

provided by HPBA, individual manufacturers, and Internet searches of product offerings. 

For numbers of manufacturers, we started with HPBA data, modified based on Internet 

searches of manufacturers of the major appliance types. Table 9 is a summary of the 

nationwide average annual NSPS-related cost increases to manufacturers. The average 

annual cost increases are presented over the 2014 to 2022 period consistent with the 
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RIA,

40 as well as over the 2013 to 2038 period. The 2013 to 2038 period encompasses the 

first year of estimated NSPS-related costs (2013) through the lifespan of models designed 

to meet the NSPS in 2014 and 2019, as explained further below and in our background 

analyses.

41

Table 9. Summary of Nationwide Average Annual Cost Increases (2010$)

Appliance Type 2014-2022 Period 2013-2038 Period

Wood Heaters $4,212,303 $1,749,726

Single Burn Rate Heaters $901,732 $456,316

Pellet Heaters/Stoves $3,460,489 $1,702,796

Forced-Air Furnaces $2,252,284 $1,171,222

Hydronic Heating 

Systems $4,554,152 $2,221,551

Masonry Heaters $307,511 $228,896

Total Average Annual 

Cost $15,688,471 $7,530,507

To develop estimates of potential unit cost increases, we used major variables 

including the estimated number of units shipped per year, the costs to develop new 

models, baseline costs of models, and the schedule by which the proposed revised NSPS 

would be implemented. Both the number of shipped units and the baseline costs of 

models were based on data from the Frost & Sullivan report, modified to address 

additional appliances or subsets of appliances. We assumed a 20-year model design 

lifespan as well as a 20-year use/emitting appliance lifespan. These assumptions were 

made to conservatively characterize the actual model design and use lifespans given that 

many models developed for the current 1988 NSPS are still being sold (after 25 years), 

 

40 See footnote 36.

41 Memo to Gil Wood, USEPA, from EC/R, Inc. Residential Heater Cost Effectiveness 

Analysis. February 26, 2013.
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many “new” models still have the same internal working parts with merely exterior 

cosmetic changes, and most residential wood heaters in consumer homes emit for at least 

20 years and often much longer. Therefore, our analysis tracks shipments and costs 

through year 2038 (i.e., 20 years after a model designed to meet the “2019” NSPS has 

completed development and is shipped). Finally, we also estimated the potential 

additional manufacturing costs to make NSPS complying models. These expenses result 

from the use of more expensive structural materials, components to enhance good 

combustion, etc. We estimated the following additional manufacturer price increases per 

unit based on appliance type:

 Certified wood heaters and pellet heaters/stoves represent a well-developed 

technology, and we could not identify price differences between models due solely to

lower emission levels compared to models with higher emission levels. Rather, price 

differences are more closely related to cosmetic differences and output. Therefore, we 

have assumed no additional manufacturing costs.

 One manufacturer estimated that it will cost an average of $100 more to manufacture 

a lower emitting single burn rate product. 

 We have seen a range of estimates for additional price increases for manufacture of a

cleaner hydronic heater, with an average being approximately $3,000 (as compared to 

a typical pre-regulation sales price of $7,500).

 We conservatively assume that the additional price increases to manufacture a 

certified forced-air furnace will be comparable to the price increases for 

manufacturing certified hydronic heaters, i.e., $3,000 (as compared to a typical preregulation price of $900).
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Our next step was to develop the following incremental cost formula: Cost of 

R&D multiplied by number of units shipped per year divided by number of models 

multiplied by model life equals the incremental cost of developing a new unit, spread 

over the number of units expected to be sold during the model life. In developing this 

calculation, we included the concept that the R&D costs per model line are recovered in 

the sales price of future models, which means that the more units that are sold or the 

longer the model life, the lower the incremental cost per unit. However, to be 

conservative in our unit cost analysis, we assumed a flat growth rate in shipments – that 

is, we assumed future shipments over the 20 years of model design life would be equal to 

the shipments estimated in the first NSPS compliance year. Where there are additional 

manufacturing costs as discussed above, we added these to the unit cost number. Table 10 

is a summary of the baseline unit costs, NSPS unit costs, and incremental cost increase.

Table 10. Summary of Unit Cost Impacts (in 2010 dollars)

Appliance Type Baseline Post-NSPS Incremental

Increase

Certified Wood Heaters $859 $883 $24

Single Burn Rate Heaters $253 $479 $226

Pellet Heaters/Stoves $1,295 $1,319 $24

Forced-Air Furnaces $912 $4,174 $3,262

Masonry Heaters $9,157 $9,245 - $9,997 $88 - $840

Hydronic Heating Systems $7,528 $13,986 $6,458

We request specific comments on these estimates, which significantly affect the 

estimates of costs per model lines and per unit sold and, thus, affect decisions on the 

affordability of candidate BSER. For example, if the number of model lines was less and 

the number of heaters per model line was greater, then the cost per unit sold would be 

less and more stringent options for BSER could be implemented sooner.
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D. What are the economic impacts?

The economic impacts of the proposed rule are estimated using industry-level 

estimates of annualized compliance cost to value of shipments (receipts) for affected 

industries. In this case, cost-to-receipts ratios approximate the maximum price increase 

needed for a producer to fully recover the annualized compliance costs associated with a 

regulation. Essentially, the revenues to producers will likely fully cover the annualized 

compliance cost incurred by producers at this maximum price increase. Any price 

increase above the cost-to-receipts ratio provides revenues that exceed the compliance 

costs. These industry level cost-to-receipts ratios can be interpreted as an average impact 

on potentially affected firms in these industries. Cost-to-receipts ratios for the affected 

product types range from 2.3 percent for pellet heaters/stoves up to 6.4 percent for single 

burn rate wood heaters for the proposed option. More information on how these impacts 

are estimated can be found in Chapters 5 and 6 of the RIA. In estimating the net benefits 

of regulation, the appropriate cost measure is “social costs.” Social costs represent the 

welfare costs of the rule to society. We believe that the social costs are best approximated 

by the compliance costs estimated for this rule. Thus, the annualized social costs for this 

proposal are best estimated to be $15.7 million for the proposed option, based on the 

estimate of costs to manufacturers for the proposal and assuming no cost pass-through to 

consumers. More information on how these social costs are estimated can be found in 

Chapter 5 of the RIA.

E. What are the non-air quality health and energy impacts?

These proposed NSPS are anticipated to have no impacts or only negligible 

impacts on water quality or quantity, waste disposal, radiation or noise. To the extent new 
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NSPS models are more efficient, that would lead to reduced wood consumption, thereby

saving timber and preserving woodlands and vegetation for aesthetics, erosion control, 

carbon sequestration, and ecological needs.

It is difficult to determine the precise energy impacts that might result from this 

proposed rule. On the one hand, to the extent that the NSPS wood-fueled appliance is 

more efficient, energy outputs per mass of wood fuel consumed will rise. However, 

wood-fueled appliances compete with other biomass forms as well as more traditional oil, 

electricity, and natural gas. We have not determined the potential for consumers to 

choose other types of fuels and their associated appliances if the consumer costs of woodfueled appliances increase and at what level that increase would drive consumer choice. 

Similarly, we have not determined the degree to which better information on the energy

efficiency of the NSPS appliances will encourage consumers to choose new wood-fueled 

appliances over other new appliances.

V. Rationale for Proposed Amendments

A. Why are we proposing to expand the scope of appliances subject to the NSPS? 

As described in section II, the EPA has had ongoing discussions with many

stakeholders regarding the need to expand the scope of the current residential wood 

heater regulation. Stakeholders described adverse health and environmental impacts 

arising from the increasing use of some appliances, actions taken at the state and local 

levels to address such concerns, and growth in types and numbers of appliances that are 

currently on the market. Numerous states have indicated to us that individuals’ concerns 

about smoke from residential wood burning, particularly by hydronic heaters, are the top 

source of environmental complaints. In the case of masonry heaters, some manufacturers 
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requested EPA certification for their devices, which might allow them to be sold in parts 

of the country that currently ban uncertified appliances (contingent upon approval by the 

local jurisdiction). We also saw a need to address the residential heating market in a way

that recognizes that some appliances and fuels are substitutes for each other. Regulating 

only one type of device may result in unintended incentives for consumers to favor 

purchase and use of unregulated and potentially higher emitting devices. We felt a 

comprehensive assessment was needed. Therefore, as part of the NSPS review process, 

we evaluated a wide range of residential biomass heating devices and non-heating 

devices (such as cookstoves and fireplaces) to determine what expansions in scope might 

be needed.

42

The residential wood heaters NSPS is a “standard of performance” as defined by

section 111(a) of the CAA. The term “standard of performance” means a “standard for 

emissions of air pollutants which reflects the degree of emission limitation achievable 

through the application of the best system of emission reduction which (taking into 

account the cost of achieving such reduction and any non-air quality health and 

environmental impacts and energy requirements) the Administrator determines has been 

adequately demonstrated.” As discussed earlier, the level of control prescribed by section

111 historically has been commonly referred to as “Best Demonstrated Technology” or 

BDT. To better reflect that section 111 was amended in 1990 to clarify that “best 

systems” may or may not be “technology,” the EPA is now using the term “best systems

of emission reduction” or BSER. As previously with BDT, in determining BSER, the 

EPA uses available information and considers the emissions reductions and incremental 

 

42 Subpart AAA—Standards of Performance for New Residential Wood Heaters: Revised 

Draft Review Document. Prepared for EPA by EC/R Incorporated. December 30, 2009.
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costs for different systems available at reasonable cost. The residential wood heaters

source category is fundamentally different from the typical NSPS source category in that 

it is mass-produced residential consumer products. Thus, important elements in 

determining that BSER has been “adequately demonstrated” include the significant costs 

and environmental impacts of delaying production and sales while models with those

systems are being designed, tested, field evaluated, and certified. The EPA determines the 

appropriate emission limits representative of BSER. After the emission limits are 

established, in general, the source may use whatever systems meet the emission limits. In

developing the proposed rule, we evaluated possible systems both at baseline conditions 

(conditions in the absence of additional regulation) and under other scenarios. In most 

cases, candidate BSER for residential wood heaters is based on improved combustion 

techniques, primarily improvements in model-specific combinations of time, temperature, 

and turbulence. That is, the improved combustion models have greater airflow residence 

time, better insulation to increase temperatures, and passageways and directed flows to 

improve mixing and turbulence. In addition, some heaters also use catalytic combustors 

to reduce emissions. Each manufacturer has a potential myriad of combinations of 

specific designs that could incorporate these key aspects. Many systems reduce emissions 

significantly, increase efficiency, and provide good operator flexibility. The key

differences tend to be confidential business information as to the specifics of the 

combination that the manufacturer uses and does not share with other manufacturers but 

rather holds as proprietary. Similarly, the industry trade association cannot facilitate 

exchange of such information because of antitrust regulations. Because each appliance 
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type has a potentially unique emissions profile, market niche, and manufacturer profile, 

we made BSER determinations for each appliance type, as described below.

For certain types of devices, information is lacking to develop BSER. For 

example, we have no information or very limited information on emissions and emission 

reduction techniques for cookstoves, pizza ovens, chimineas, coal stoves and biomass 

(other than wood or wood pellet) stoves/furnaces (e.g., fueled with grass, corn, cherry

pits). We are interested in receiving data for coal stoves and biomass stoves because we

believe we do not have sufficient information at this time to develop proposed standards. 

Also, usage rates of some of these appliances are limited both in numbers of new units 

and in the number of markets they occupy. For example, some stakeholders have stated 

that use of coal stoves is more common in some coal mining regions, where the consumer 

may have access to free or cheap coal, but such stoves are not typically used in other 

areas. We request data on any of these appliances that might help us potentially develop 

national programs or standards for these devices in the future.

We are also deferring any regulatory action addressing emissions from woodburning fireplaces at this time. Fireplaces typically are not designed to be “wood heaters” 

and thus are not within the current scope of the “residential wood heater” source category

listed pursuant to the authority of section 111(b). (Fireplaces are typically used for 

ambience and most of the heat content of the wood is lost out the chimney rather than 

heating the room. For effective heating, some homeowners have inserted a new wood 

stove into an otherwise open masonry fireplace. In those cases, new wood heaters/stoves

are regulated under the current 1988 rule and would be regulated by this proposal.)

Fireplaces are addressed in the current EPA voluntary partnership program that 
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encourages the development and sale of lower-emitting wood-burning fireplaces over the 

sale of higher-emitting fireplaces. The EPA's fireplace program covers new masonry and 

prefabricated (low-mass) fireplaces and retrofit devices for existing fireplaces. See the 

voluntary partnership program website for more information: 

http://www.epa.gov/burnwise/participation.html#fireplace. We request comments and 

additional data on fireplaces that might help us potentially develop new or revised 

national programs or standards for these devices in the future. We are especially

interested in data on current and projected sales of new wood-burning fireplaces versus 

gas-fired fireplaces, current and projected usage patterns for new fireplaces versus 

existing fireplaces, current and projected quantities of wood burned per existing and new 

fireplaces, current and projected best systems of emission reduction for new fireplaces 

versus existing fireplaces and costs of current and projected best systems versus current 

costs of fireplaces. Also, we are interested in national data and also how these data vary

by state and local areas.

B. How did we determine BSER and the proposed emission standards? 

As discussed earlier in this preamble, the proposed subparts AAA, QQQQ, and 

RRRR recognize that the sources covered by these subparts are fundamentally different 

from the typical NSPS source category in that they are mass-produced residential 

consumer products whereas most NSPS regulate industrial processes. Discussions in 

sections V.B.1 through V.B.4 of this preamble focus on the analysis of PM emission 

reductions under our proposed two-step phased-in standards for each appliance type 

affected by this proposal. In general, for this rulemaking, we have determined that the 

proposed first step represents the emission levels that almost all models can achieve now 
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using today’s designs and technology. Further, we have determined that the proposed 

second step represents stronger emission levels achievable for all appliance types at 

reasonable cost, but allows appropriate lead times for manufacturers to redesign their 

model lines to accommodate the improved technology across model lines and test, field 

evaluate, and certify the new model lines. See section V.B.5 for a discussion of the 

Alternative Approach we considered to reduce PM emissions based on three-step phasedin standards, under which the strongest emission standard would have a compliance date 

of 2022 rather than the proposed 2019 compliance date. Section V.B.6 discusses other 

provisions we considered and for which we request additional data and information from 

commenters.

For these source categories, our BSER determination rests on: (1) the 

achievability of the proposed emission levels (i.e., the fact that top- performing models 

for each appliance type are already achieving the proposed emission levels); and (2) the 

cost effectiveness of the proposed standards when considering the design lifespan and the 

emitting lifespan of the appliances in residences. The net monetized benefits of the 

proposal far exceed the costs for all options considered. Realistic model design and 

appliance emitting lifespan assumptions are essential components for a meaningful cost 

effectiveness analysis. As explained above in section IV.C. and in our background 

documentation,

43 a model design lifespan of 20 years is supported by the fact that the 

non-cosmetic aspects of wood heaters designed to meet the 1988 NSPS are still being 

used today in some model lines. While some manufacturers may choose to make more 

frequent cosmetic changes to their models, the internal design changes a manufacturer 

 

43 See footnotes 24, 37 and 38.
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must make to a wood heater model line to comply with the NSPS are longer lasting. 

Furthermore, it is a conservative assumption that, once installed in consumer homes,

wood heaters emit for at least 20 years, because many are operated in residences for

much longer time periods (a key fact motivating wood heater/stove changeout programs).

Consumers tend to replace appliances when they no longer serve their functional purpose, 

not based on whether they are the cleanest, best performers currently available. Wood 

heaters tend to serve the basic function of producing heat for well over our conservative 

estimate of 20 years. Table 11 presents our estimated cumulative costs, PM2.5 emission 

reductions, and associated cost per ton for our proposed limits, based on a model design 

lifespan of 20 years and an appliance emitting lifespan of 20 years.

For all of the standards proposed in this Federal Register notice, the EPA invites 

specific comments on the data and analyses on which we base the proposed standards. 

Moreover, the EPA invites specific comments that provide additional data and analyses 

that would support a different standard. Interested persons should note that the EPA will 

consider promulgating a more stringent or less stringent standard than what we are 

proposing for any of these categories, if the record contains data or analyses that support 

a different standard.
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Table 11. Cost Effectiveness of PM2.5 Benefits of Proposed Standards and Emission Co-Benefits based on Cumulative

Analysis (2013-2057)44

Appliance 

Type

Nationwide 

Cumulative 

Cost (2010$)

PM2.5 Benefits of Standard VOC Co-Benefit CO Co-Benefit

Cumulative 

Emission 

Reduction (tons)

Cost per ton 

(2010$)

Cumulative 

Emission 

Reduction (tons)

Cost per ton 

(2010$)

Cumulative 

Emission 

Reduction (tons)

Cost per ton 

(2010$)

Wood 

Heaters $45,492,874 96,523 $471 136,293 $334 1,426,240 $32

Single Burn 

Rate Heaters $11,864,204 236,254 $50 416,828 $28 1,602,218 $7

PelletHeaters

/ Stoves $44,272,694 29,269 $1,513 392 $112,894 152,082 $291

Furnace: 

Indoor, Cord 

wood $30,451,763 823,770 $37 349,207 $87 5,491,797 $6

Hydronic 

Heating 

Systems $57,760,316 360,587 $160 $152,858 $378 2,403,916 $24

Total* $189,841,851 1,546,403 $123 1,055,578 $180 11,076,253 $17

*Note: Masonry Heaters are not included in this analysis because no representative emission tons per appliance could be 

determined; however, emission reductions for these appliances are not expected to be significant based on the proposed limits.

 

44 Analysis period is based on the assumption that manufacturers will incur R&D costs beginning in 2013, in anticipation of 

the final rule. Analysis includes years through 2057, based on the assumption that the internal emission-related components of 

a model designed to meet the proposed 2019 BSER limit will be manufactured/shipped for 20 years, and furthermore that 

shipped models will emit in residences for another 20 years. See footnote 40.
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1. Room Heaters

The current subpart AAA definition of “wood heater” specifies certain conditions, 

including that affected sources are those that have an air-to-fuel ratio of less than 35:1. As 

part of the regulatory negotiation for the current 1988 NSPS, the EPA included the air-tofuel criterion in the rule primarily to exclude fireplaces from the affected source 

definition. An unintended side effect, however, is that it also resulted in the exclusion of 

the majority of pellet heaters/stoves. Also included in the current 1988 NSPS definition 

of “wood heater” is an exclusion of heaters that have a minimum burn rate of greater than 

5 kg/hr. The definition and test methods had the effect of excluding a large number of 

single burn rate wood heaters. As described below, we are proposing to change the 

applicability of subpart AAA to include all three types of “room heater” appliances: 

adjustable burn rate wood heaters, pellet heaters/stoves and single burn rate wood heaters. 

Our intent is that this rule will be stated in broad enough terms to regulate any future 

room heater appliances that may come into the U.S. market and function as room heaters.

a. Adjustable Burn Rate Wood Heaters

Adjustable burn rate wood heaters include freestanding heaters and heaters 

modified to fit within a firebox (sometimes called fireplace inserts). These units were the 

primary focus of the 1988 NSPS and are subject to current NSPS limits of 7.5 g/hr for 

noncatalytic heaters and 4.1 g/hr for catalytic heaters. As discussed in the February 26, 

1988, final rule (53 FR 5865) and earlier in this preamble, the EPA considered the 

performance of catalytic heaters and noncatalytic heaters co-BDT (now called BSER) 

because the net emissions over time were estimated to be similar (even though the initial 

certification test results are typically lower for catalytic models) assuming possible 
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degradation of the catalyst and lack of catalyst replacement by the operator. The EPA 

considered requiring catalyst replacement on a regular schedule, but determined that 

enforcement of such a requirement would be difficult. The EPA did require 

manufacturers to provide 2-year unconditional warranties on the catalysts and prohibited 

the operation of catalytic heaters/stoves without a catalyst. Additionally, because of these 

concerns, the EPA wanted to ensure that further development of both noncatalytic and 

catalytic technology would continue.

Since the 1988 NSPS was developed, the State of Washington issued standards in 

1995 imposing limits of 4.5 g/hr for noncatalytic heaters and 2.5 g/hr for catalytic 

heaters. In developing the proposed revisions to the NSPS, we evaluated and identified 

these “improved” catalytic and noncatalytic systems and associated emission levels as the 

proposed Step 1. This analysis showed that the State of Washington level of 4.5 g/hr is 

achieved by 107 out of 121 (88 percent) of the EPA-certified adjustable burn rate wood 

heater models in production and sold in the U.S. today (noncatalytic and catalytic models 

combined). This statistic includes 92 of the 106 certified noncatalytic wood heater 

models (87 percent) and 15 of the 15 certified catalytic models (100 percent). The median 

certification value for noncatalytic models was 3.2 g/hr and for all certified models was

3.4 g/hr. Details of the analysis are in the docket.45

For the proposed Step 2 (5 years after the effective date of the final standard), we 

considered “state-of-the-art” systems that achieve a certification value of 1.3 g/hr. This is 

approximately 50 percent less than the 1995 Washington standard for catalytic models 

(2.5 g/hr). The same analysis discussed above showed that a level of 1.3 g/hr is achieved 

 

45 Attachment A of Residential Wood Heaters Manufacturer Cost Memorandum to Gil 

Wood, USEPA, from EC/R Inc. February 22, 2013.
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by 7 adjustable burn rate wood heater models in production and sold in the U.S. today

(noncatalytic and catalytic models combined). This includes 4 certified noncatalytic 

wood heater models and 3 certified catalytic models. There were no apparent break points 

other than the current State of Washington initial certification level of 4.5 g/hr for 

noncatalytic heaters. That is, the distribution of certification values was relatively linear 

with no step functions other than at the State of Washington level of 4.5 g/hr.

Considering that this source category is fundamentally different from the typical 

NSPS source category in that it is the manufacture and sale of mass-produced residential 

consumer products that are significantly affected by production and sales volumes and 

timing of testing and certification, we are proposing implementing the proposed Step 2

BSER standard 5 years after the effective date of the final standard to allow for longer 

lead times for redesign, testing, field evaluation and certification. This also spreads the 

costs over a longer time and a larger number of units. The intent behind the proposed 

Step 2 BSER standard is to recognize that current state-of-the-art level of performance 

appears to be significantly better than the State of Washington limit of 4.5 g/hr met by

over 85 percent of the heaters sold today on a sales-weighted basis (i.e., 92 out of 106 

noncatalytic models and 15 out of 15 catalytic models), and furthermore better than the 

State of Washington catalytic limit of 2.5 g/hr for over 25 percent of the adjustable burn 

rate wood heaters sold in the U.S. today (i.e., 20 out of 106 or approximately 19 percent 

of noncatalytic models and 13 out of 15 or approximately 87 percent of catalytic models). 

As noted earlier and discussed more fully in the paragraphs below, our decisions on 

BSER for this source category have fully considered not only the emission performance 

but also the cost and economic impacts, including the costs to accommodate the best 
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systems in additional model lines. The net monetized benefits far exceed the costs of all 

options considered.

The cost impacts of the proposed Step 1 are very small. This is because, despite 

being a limit that was originally developed for only one state, over 85 percent of currently 

EPA-certified non-catalytic and catalytic heaters that are in active production already 

meet the State of Washington initial certification test values. We also believe production 

of any certified heaters that do not meet the proposed Step 1 standard would be 

discontinued, as manufacturers would make their own prudent business decisions to focus 

on models that already comply with the proposed standard in the short term. While 

implementing the proposed Step 1 standard would not impose any significant additional 

costs on most of the manufacturers, it also would not achieve a large amount of new 

emissions reductions for most of the models. However, implementing an emission 

standard associated with the proposed Step 1 would have the benefit of ensuring 

consistent nationwide standards and ensuring that the remaining 15 percent of noncomplying adjustable burn rate wood heater models could no longer be sold. It would 

also ensure that wood heater/stove changeout programs aimed at reducing emissions from 

old, pre-NSPS or pre-State of Washington heaters/stoves would result in replacement 

models that meet the State of Washington levels or better.

The proposed Step 1 limit eliminates the distinction between catalytic and noncatalytic heater models, which we view as an advantage. It is important to remember that 

the lower emission level catalytic standards were initially instituted because of concerns 

that the early generation catalysts would degrade over time, resulting in eventual real 

world emission levels comparable to non-catalytic units. After 25 years of catalyst heater 
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development experience, manufacturers have demonstrated that the performance of these 

heaters typically remains consistently good over the course of operation because of 

changes manufacturers have made to improve heater design to increase combustor

longevity. For example, one recent study of four catalytic combustors from the two 

selected heaters/stoves showed that the combustors maintained substrate integrity without 

substantial PM emissions performance reduction.46 Therefore, establishing a separate 

limit to accommodate “degradation” seems to create a distinction where none exists and 

adds unnecessary confusion to the overall regulation.

We recognize that there may be concern that a single limit based on the 

Washington State non-catalytic limit could result in “backsliding” of current catalytic 

heater models. We think that the likelihood of such backsliding is extremely low because 

of other factors driving the wood heater market. Given the pending implementation of the 

proposed Step 2 limits described below, all manufacturers would have market incentives 

to improve performance as soon as possible rather than degrade performance. Also, with 

consumer education regarding the impacts of PM emission levels, we believe that 

consumer pressure will favor better performing units that in general are more energy

efficient and lower emitting. However, we are requesting comments on whether we 

should maintain a separate, lower limit for catalytic heater models for the proposed Step 

1 emission limits, based on the current State of Washington catalytic standard of 2.5 g/hr.

The proposed Step 2 state-of-the-art BSER cost and economic impacts would be 

significant, but our analysis shows a very reasonable cost per ton of emission reduction 

 

46 The Interim Wood Stove Catalytic Combustor Longevity Study, Prepared for the 

Catalytic Hearth Coalition by L. Pitzman et al, OMNI Environmental Services. January

4, 2010.
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when considering the typical design and appliance lifespans.

47 Our data show that at the 

proposed Step 2 BSER emission level of 1.3 g/hr, about 20 percent of catalytic models 

and 5 percent of noncatalytic models currently manufactured would already comply with 

the proposed Step 2 standard. Thus, manufacturers would need to either modify

noncomplying lines or develop new ones to continue production for approximately 95 

percent of the current market. Some unknown fraction of manufacturers may be able to 

switch some of their production from noncomplying models to complying models, but 

because we do not know this fraction, because the total of complying units is only 6 

percent (combined catalytic and non-catalytic models) at this time, and because many

manufacturers have no complying models at this time, we have conservatively assumed 

this fraction to be zero for our analysis. Historically, those manufacturers that chose to 

comply with the 1988 NSPS did so for a full range of models. Thus, our analysis shows 

the potential emission and cost impacts for the approximately 95 percent of adjustable 

burn rate wood heater models projected to undertake R&D needed to develop the heaterspecific combinations of time, temperature, and turbulence to achieve higher efficiencies 

and lower (proposed Step 2 compliant) emissions. That is, although the manufacturers 

know the factors that are important for good combustion and low emissions, they still 

need to develop and test in the laboratory-specific combinations that can be incorporated 

into the design of specific model lines. Alternatively, some manufacturers might convert 

noncatalytic models to catalytic models or hybrids as ways to reduce emissions.

We conservatively estimated the resulting nationwide costs based on the cost 

assumptions explained in section IV.C. The average annual cost increase to 

 

47 See footnote 40.
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manufacturers of adjustable burn rate wood heaters during the 2014 through 2022 period 

used in the RIA is approximately $4.2 million. Estimated nationwide annual PM2.5

emissions, averaged over this same period (2014-2022), are projected to be 548 tons/year 

under baseline conditions versus 385 tons/year under the proposed two-step BSER, an 

average reduction of 163 tons/year. Given these cost and emission estimates, the average 

cost of reducing each ton of PM2.5 emissions during the 2014-2022 period is 

approximately $26,000 per ton annually. As explained in section IV.C, the cost-to-sales 

ratio, which is a measure of the ability of the manufacturer to successfully absorb the 

regulatory impacts, is somewhat high at 4.3 percent. When considering the total costs and 

cumulative emission reductions over the more representative full model design lifespan 

and appliance emitting lifespan of 20 years; however, the overall cost effectiveness is 

approximately $500 per ton (shown above in Table 11).

48

Given the reasonable cost effectiveness of imposing the two-step BSER when 

considering total costs and cumulative emission reductions, and given the 6-year lead 

time (from the date of these proposed standards) until models must meet the proposed 

Step 2 limit, we determined that the two-step phased-in limits represent BSER for these 

residential consumer product appliances at this time. Thus, we are proposing a two-step 

standard for adjustable burn rate wood heaters, in which Proposed Step 1 is required upon 

the effective date of the final rule and Proposed Step 2 is required 5 years after the 

effective date of the final rule. Section V.B.5 discusses a three-step alternative approach 

that we also considered for adjustable burn rate wood heaters, and on which we are 

seeking comment.

 

48 See footnote 40.
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We note that there have been some technical questions associated with measuring 

the emission levels associated with the proposed Step 2, which we are addressing in this

proposed rule. That is, the currently available laboratory proficiency test results cast some 

doubt on the reproducibility of test results at lower levels of the standard for the current 

EPA Test Method 28. An HPBA analysis49 found that the repeatability and 

reproducibility of the current test method for wood heater emissions, as demonstrated by

the EPA-accredited laboratory proficiency test data, may be poor based on the scope of 

their analysis. Their analysis stated:

 “At the 95-percent confidence level, repeatability for the EPA weighted average 

emission rate is at best ±2.9 g/hr and ranged as high as ±5.4 g/hr.”

 “The reproducibility was no better than ±4.5 g/hr and ranged as high as ±6.4 g/hr.”

We believe some mitigating factors are not accounted for in their analysis, such as 

the lack of regulatory requirements or incentives for the test laboratories to achieve 

highly reproducible results in proficiency testing (i.e., the laboratories are not required to 

meet a certain proficiency level; they are not paid for the proficiency tests, but rather they

absorb the costs as part of their overhead; and, in some cases, they intentionally staged 

the test to demonstrate that variability was possible within the current protocol). Also, 

these factors do not reflect the proposed changes to improve the repeatability and 

reproducibility of the test method. Consequently, we believe the previous results merit 

consideration of concerns about implementing a lower emission standard, but they do not 

mean that lower emission standards cannot be measured accurately. For example, the 

 

49 Final Report: EPA Wood Heater Emission Test Method Comparison Study. Prepared 

by Robert Ferguson, Ferguson, Andors & Company for the Hearth, Patio and Barbecue 

Association. December 1, 2010.
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State of Washington Department of Ecology has successfully used lower emission levels 

in their regulations since 1995, and the Oregon Department of Environmental Quality has 

used lower levels for tax credits for low-emitting pellet heaters/stoves. 

b. Pellet Heaters/Stoves

Several certified pellet heaters/stoves are subject to current subpart AAA. 

However, most models currently offered for sale are exempt due to air-to-fuel ratios 

greater than 35:1. We considered candidate options similar to those discussed earlier for 

wood heaters/stoves, i.e., improved catalytic and improved noncatalytic systems and 

state-of-the-art systems. Our data set for currently manufactured U.S. pellet 

heaters/stoves, for which we have reproducible emissions data, contains 24 models, of 

which 23 would meet the 4.5 g/hr proposed Step 1 BSER emission limit. We also 

compared the listings of certified pellet heaters/stoves for both the EPA and the State of 

Washington. Of the 224 pellet heater/stove models from both lists, 221 models produced 

by 35 manufacturers would meet the State of Washington emission standard. Only three 

models produced by three manufacturers would not meet the standard. Assuming that the 

rest of the pellet heater/stove market has comparable performance, we would expect to 

see only a small cost impact of requiring the proposed Step 1 BSER emission levels of 

4.5 g/hr for noncatalytic and catalytic pellet heaters in terms of having to redesign units to 

meet the proposed Step 1 BSER. 

Even though additional R&D would not be required to meet the proposed Step 1 

BSER, manufacturers would need to test and certify their heaters/stoves to sell them after

the effective data of the final rule, which we expect to occur in 2014. Pellet heaters/stoves 

would incur these testing and certification costs starting in 2013 in anticipation of the 
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final rule. They would also incur ongoing recertification costs for the fraction of 

heaters/stoves with expiring certifications. 

Some stakeholders have argued that pellet heaters/stoves are relatively cleaner 

burning than other wood heaters and that regulation is not needed. Other stakeholders 

have argued that pellet heater/stove standards should be tighter to show how clean they

are and encourage consumers to purchase pellet heaters/stoves instead of cord wood 

heaters/stoves. Considering both positions, and because pellet heaters/stoves are cleaner 

burning in general, we think there is environmental value in ensuring they have an EPA 

certification so they can be sold in jurisdictions that require such certification of any

wood-burning appliance (contingent upon approval by the local jurisdiction). This would 

help avoid a competitive imbalance regarding wood heaters. Also, we believe there is 

environmental value in having third-party accredited laboratory test results available in 

all areas so that consumers can make informed choices among competing residential 

heaters.

We are also proposing implementation of a Step 2 state-of-the-art BSER 5 years 

after the effective date of the final rule. We estimate that at least 30 percent of current 

U.S. pellet heater/stove models already meet the proposed Step 2 emission level. We 

assumed that manufacturers will either modify the remaining models or invest in 

developing new model lines that can meet the proposed Step 2 emission level. This 

conservative assumption may somewhat overstate the potential cost and economic 

impacts of requiring a proposed Step 2 BSER, because some noncomplying models will 

be dropped and manufacturers may consolidate their model lines in the short term. 
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However, we do not know how many models will be dropped. This industry has a history

of manufacturing a wide range of choices of models for the marketplace. 

The nationwide annualized total costs are significant based on our conservative 

cost assumptions explained in section IV.C. and in our background documentation.50 The 

average annual cost increase to manufacturers of pellet heaters/stoves during the 2014 

through 2022 period used in the RIA is approximately $3.5 million. Estimated nationwide 

annual PM2.5 emissions, averaged over this same period (2014-2022), are projected to be 

199 tons/year under baseline conditions versus 150 tons/year under the proposed two-step

BSER, an average reduction of 49 tons/year. Given these cost and emission estimates, the 

average cost of reducing each ton of PM2.5 emissions during the 2014-2022 period is 

approximately $71,000 per ton annually. The annualized cost-to-sales ratio is 2.3 percent. 

However, when considering the total costs and cumulative emission reductions over the 

full model design lifespan and appliance emitting lifespan of pellet heaters/stoves, the 

overall cost effectiveness is approximately $1,500 per ton (shown above in Table 11).

51

 

Given the reasonable cost effectiveness of imposing the proposed two-step BSER

when considering total costs and cumulative emission reductions, and given the 6-year 

lead time (from the date of these proposed standards) until model lines must come into 

compliance with the proposed Step 2 limit, we determined that the two-step phased-in 

limits represent BSER for these residential consumer appliances at this time. Thus we are 

proposing a two-step standard for pellet heaters/stoves, in which Proposed Step 1 is 

required upon the effective date of the final rule, and Proposed Step 2 is required 5 years 

after the effective date of the final rule. Section V.B.5 discusses a three-step alternative 

 

50 See footnotes 37 and 38.

51 See footnote 40.
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approach that we also considered for pellet heater/stoves, and on which we are seeking 

comment.

c. Single Burn Rate Wood Heaters

Single burn rate wood heaters represent a huge regulatory exemption in the 

current residential wood heater market. We estimate that over 40,000 of these units are

sold per year. We evaluated all of the available emission data and discussed the state of 

research and development with manufacturers of single burn rate wood heaters. The data 

show that the BSER for single burn rate wood heaters based on improved combustion 

could achieve the same emission levels for one individual burn rate category as 

adjustable burn rate category wood heaters do for the weighted average of four burn 

rates. To compare single burn rate emissions to adjustable burn rate emissions, however, 

one must remember that single burn rate wood heaters are by definition incapable of 

operating at the lowest burn rates, and that these low burn rates result in the greatest level 

of emissions in an adjustable burn rate wood heater. Thus, the certification test method 

for single burn rate wood heaters must be modified to take the single burn rate into 

account (instead of the multiple burn rates for the adjustable rate heaters). For example a 

rate of 3.0 g/hr could be considered to be equivalent to the State of Washington standards 

(of 4.5 g/hr for adjustable burn rate wood heaters) adjusted to the single burn rate.

Considering that single burn rate wood heaters will not be expected to operate at 

the typically dirtier burn rates, we expect the majority of single burn rate wood heaters to 

meet the proposed Step 1 BSER limit of 4.5 g/hr for adjustable burn rate wood heaters, if 

the design is focused on one optimal single burn rate. However, some models would 

require modifications to ensure that they consistently pass the test and to add tamper-
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proof settings to ensure that operators do not circumvent the intent of the NSPS. We 

adopted a conservative assumption that all existing models would need to be modified 

through R&D, resulting in significant emission reductions to achieve the proposed Step 1 

BSER. We request specific data and comments regarding these assumptions. Since 2009, 

single burn rate wood heater designs have been undergoing R&D in anticipation of the 

proposed NSPS, and the information that we have from industry is that cleaner designs 

are nearly market-ready.

52 Nonetheless, because these devices were previously

unregulated and may need to transfer technology from adjustable burn rate wood heaters, 

our cost analysis conservatively assumes that research and development efforts will 

intensify in 2013 and 2014 in order to meet the proposed Step 1 standard while also 

beginning R&D to develop models to meet the more stringent proposed Step 2 BSER 

limit. Specifically, for single burn rate wood heaters, we doubled our R&D estimate of 

$356,250 per model for other appliances in these years.

The nationwide annualized total costs are based on the cost assumptions 

explained in section IV.B and in the background documentation.53 The average annual 

cost increase to manufacturers of single burn rate heaters during the 2014 through 2022 

period used in the RIA is approximately $902,000. Estimated nationwide annual PM2.5

emissions, averaged over this same period (2014-2022), are projected to be 932 tons/year 

under the baseline (unregulated) condition versus 178 tons/year under the proposed twostep BSER, an average reduction of 754 tons/year. Given these cost and emission 

estimates, the average cost of reducing each ton of PM2.5 emissions during the 2014-2022 

period is approximately $1,200 per ton annually. The cost-to-sales ratio is 6.4 percent, if 

 

52 See footnote 37.

53 See footnotes 37 and 38.
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calculated based on only the initial 5-year period. However, when considering the total 

costs and cumulative emission reductions over the representative full model design 

lifespan and appliance emitting lifespan, the overall cost effectiveness is approximately

$50 per ton (shown above in Table 11).54

Given the reasonable cost effectiveness of imposing the two-step BSER when 

considering total costs and cumulative emission reductions, and given the 6-year lead 

time (from the date of these proposed standards) until new model lines must meet the 

proposed Step 2 emission limit, we determined that the two-step phased-in limits 

represent BSER for these residential consumer appliances at this time. Thus, we are 

proposing a two-step standard for single burn rate wood heaters, in which Proposed Step 

1 is required upon the effective date of the final rule and Proposed Step 2 is required 5

years after the effective date of the final rule. Section V.B.5 discusses a three-step 

alternative approach that we also considered for single burn rate wood heaters, and on 

which we are seeking comment.

2. Central Heaters

We are proposing subpart QQQQ for wood-burning appliances that function as 

“central heaters” with the purpose of heating the entire residence, including current new 

residential hydronic heaters and forced-air furnaces. Our intent is that this rule will be 

stated in broad enough terms to regulate any future central heater wood-burning 

appliances that may come into the U.S. market and function as central heaters. In this 

section, we describe our rationale for determining BSER and the associated proposed 

emission standards for both hydronic heating systems (“hydronic heaters”) and forced-air 

 

54 See footnote 40.
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furnaces. As discussed earlier in this preamble, the source categories to be regulated by

proposed subparts AAA, QQQQ, and RRRR are fundamentally different from the typical 

NSPS source category in that they are mass-produced residential consumer products 

whereas most NSPS regulate industrial processes. Thus, additional factors are included in 

the analyses presented today. Section V.B.2.a. below discusses hydronic heaters. Section 

V.B.2.b. discusses forced-air furnaces.

a. Hydronic Heaters

As described in section II.D, hydronic heaters (commonly known as “outdoor 

wood boilers” although there are indoor units as well) are the subject of an EPA 

voluntary partnership program, started in January 2007. The EPA’s voluntary partnership 

program provided criteria in 2007 for qualification of units to be approximately 70 

percent cleaner than unqualified models (Phase 1, “orange hangtag”). In October 2008, 

the program evolved to Phase 2, and EPA-qualified Phase 2 (“white hangtag”) units are 

approximately 90 percent cleaner than older, pre-program unqualified units. Under the 

Phase 2 voluntary partnership program, new qualified models must emit no more than 

0.32 lb/MMBtu of heat output and have a cap of 18 g/hr on any individual test run 

conducted during the qualifying test. (As noted in the hydronic heaters test method 

discussion in this preamble, the EPA, the manufacturers, the laboratories, and key states 

conducted a thorough additional review of the test reports to support these qualifications 

and made some changes to the test methods to improve the reliability and reproducibility

of the test results.) 

The proposed Step 1 limit for hydronic heaters is the Phase 2 limit of the hydronic 

heater voluntary partnership program, 0.32 lb/MMBtu. There are currently 36 models (27 
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cord wood and 9 pellet models) built by 17 U.S. manufacturers that have been qualified 

to meet the 2008 Phase 2 level of 0.32 lb/MM BTU.55 In almost all cases, the 

manufacturers developed models that rely upon improved combustion techniques, 

primarily improvements in time, temperature, and turbulence. That is, the improved 

combustion models have greater residence time, separation of the firebox and the water 

jacket and the addition of better heat exchangers and better insulation to increase 

temperatures, and passageways and directed flows to improve mixing and turbulence. In 

some cases, manufacturers are also using catalyst technology. Each manufacturer has

developed their own confidential business combinations of specific designs that 

incorporate these key aspects and some other techniques.

In addition to the voluntary partnership program, the EPA provided technical and 

financial support for NESCAUM to develop a model rule for outdoor hydronic heaters, 

which several states have adopted or plan to adopt to regulate those units in their 

jurisdictions. The model rule Phase 2 emission limits and the voluntary partnership 

program Phase 2 emission levels/caps are identical, and are the same as our proposed 

Step 1 limit. In several states, the Phase 2 emission levels have become regulatory

requirements for new units. Based on our experience with the hydronic heater market 

through the voluntary partnership program, we understand that it is dominated by a few 

manufacturers in terms of the bulk of sales, and each of these manufacturers has at least 

one qualifying model already.

 

55 A list of cleaner hydronic heaters participating in the EPA’s voluntary partnership 

program is located at http://www.epa.gov/burnwise/owhhlist.html.
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For these reasons, we consider the Phase 2 voluntary partnership program level 

the appropriate emission level for the NSPS proposed Step 1 BSER, effective upon the 

effective date of the final rule. As noted above, there are currently 36 models (27 cord 

wood and 9 pellet models) built by 17 U.S. manufacturers that have already been 

qualified to meet the Phase 2 voluntary partnership program level of 0.32 lb/MM BTU. 

The EPA believes the proposed Step 2 limit for hydronic heaters is achievable for 

some manufacturers now and would be achievable for most manufacturers 5 years after

the effective date of the final rule. We consider this compliance period a reasonable 

amount of time for manufacturers to complete development across model lines and 

complete testing, field evaluation, and certification so that sufficient models are ready for 

sale. We reviewed all the hydronic heater emission data available, and we found our 

proposed Step 2 emission limit of 0.06 lb/MMBtu is already met by 4 hydronic heater 

models (2 cord wood and 2 pellet models) built by 2 U.S. manufacturers,

56 as well as 

over 50 European models per test method EN 303-05.57

Our review of the available data also showed a break point at the emission level 

of 0.15 lb/MMBtu heat output. We considered this break point as a candidate for interim 

Step 2 in the three-step Alternative Approach, as discussed in section III above. Several 

years ago, we informally discussed the 0.15 lb/MMBtu level with the voluntary program 

stakeholders, including states and manufacturers, as a potential future “Phase 3” interim 

target in the voluntary partnership program to reduce emissions to approximately one-

 

56 See footnote 54.

57 European Wood-Heating Technology Survey: An Overview of Combustion Principles 

and the Energy and Emissions Performance Characteristics of Commercially Available 

Systems in Austria, Germany, Denmark, Norway, and Sweden; Final Report; Prepared 

for the New York State Energy Research and Development Authority; NYSERDA 

Report 10–01; April 2010.
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half of the Phase 2 voluntary partnership program level. Some of the manufacturers 

responded quickly to this informal target and now 11 of the 36 models (6 cord wood and 

5 pellet models) that currently qualify under the Phase 2 voluntary partnership program

already qualify at an emission level of 0.15 lb/MMBtu or better.

The proposed BSER levels include both outdoor hydronic heaters and indoor 

hydronic heaters. The initial manufacturers who actively participated in the voluntary

partnership program were primarily manufacturers of outdoor units, due to the very large 

concern about the health effects of emissions from the outdoor units and the fact that over 

90 percent of hydronic heater sales were and still are for outdoor models. When we 

moved to Phase 2 of the voluntary partnership program in October 2008, we explicitly

included indoor units to more strongly encourage cleaner indoor units and to provide 

another tool for the states and local jurisdictions, especially since some states were 

concerned that some dirty indoor units were avoiding rules that only specified outdoor 

units. Some manufacturers of indoor models have expressed concern that the EPA and 

the outdoor hydronic heater manufacturer partners did not adequately and proactively 

seek their input at that time and that is why their participation in the voluntary partnership 

program was not as great as the outdoor hydronic heater manufacturers. Consequently, 

some believe this is the reason they effectively delayed their research into developing 

potentially qualifying models. We do not agree that we did not proactively seek their 

input on the expansion of the voluntary partnership program. Given the number of years 

the voluntary partnership program has already been in existence, we believe our proposed 

Step 1 limit upon the effective date of the final rule and the proposed Step 2 limit 5 years 

after the effective date of the final standard provide reasonable lead time to incorporate 
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BSER in both outdoor and indoor residential consumer models. We ask for specific 

comments and data on this determination and the degree to which other options would be 

appropriate.

We estimate that there are 30 manufacturers producing approximately 120 

hydronic heater models for sale in the U.S. On a sales-weighted basis, less than 25 

percent of the models currently sold would need to undertake R&D to meet the proposed 

Step 1 BSER limit, with a higher percentage that would need to undertake R&D to meet 

the proposed Step 2 BSER limit. We assumed that any manufacturer undertaking R&D to 

develop a new model would aim to meet the proposed Step 2 limit to maximize the 

lifetime of the resulting product, while shifting production to models that already meet 

the proposed Step 1 limit. In order to be conservative in our cost analysis, we assumed 

that 100 percent of the 120 hydronic heater models would incur NSPS-related R&D costs 

starting in 2013 to achieve especially the proposed Step 2 BSER limit. Considering 

typical R&D lead times, and even the different starting dates for outdoor versus indoor 

manufactures, we concluded that 5 years after the effective date of the final standard is 

an achievable compliance deadline for both outdoor and indoor models, if they were to 

start their R&D now. As discussed earlier in this preamble, most manufacturers have 

known of the hydronic heater emission concerns for over 5 years already.

We also investigated the performance of European models in considering BSER 

options. Several European countries have already established emission limits, and they

are considering more stringent limits in the near future. This has encouraged the 

European industry to develop more energy efficient and lower emitting technologies. 

Most of these state-of-the-art models use multiple-stage combustion and some use 
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lambda controls to help optimize combustion conditions. A concern in comparing the 

emission performance of European models with North American models is the difference 

in test methods. However, a recent report58 included an effort to compare the 

performance of the European models to U.S. type performance standards. Although a 

perfect comparison is not possible due to differences in duty-cycle (i.e., proportion of 

time the unit is operating) to be evaluated in the test and the emissions sampling and 

analysis protocols, the analysis indicates that the top 20 percent performing European 

wood boilers (i.e., hydronic heaters) in the size range of 120,000 - 170,000 Btu would 

meet an output-based emission rate of 0.06 lb/MMBtu using the European test methods. 

The underlying test data and limited comparative testing show that over 50 models would 

be considered state-of-the-art BSER and be capable of meeting the proposed Step 2

BSER associated emission level of 0.06 lb/MMBtu heat output. 

The nationwide annualized total costs are based on the cost assumptions 

explained in section IV.C and in the background documentation.59 The average annual 

cost increase to manufacturers of hydronic heaters during the 2014 through 2022 period 

used in the RIA is approximately $4.6 million. Estimated nationwide annual PM2.5

emissions, averaged over this same period (2014-2022), are projected to be 1,332

tons/year under the baseline (unregulated) condition versus 84 tons/year under the 

proposed two-step BSER, an average reduction of 1,249 tons/year. Given these cost and 

emission estimates, the average cost of reducing each ton of PM2.5 emissions during the 

2014-2022 period is approximately $3,600 per ton annually. The annualized cost-to-sales 

ratio is 3.3 percent for hydronic heater models. When considering the total costs and 

 

58 See footnote 56.

59 See footnotes 37 and 38.
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cumulative emission reductions over the full model design lifespan and appliance 

emitting lifespan; however, the overall cost effectiveness is approximately $160 per ton 

(shown above in Table 11).60

Given the reasonable cost effectiveness of imposing the two-step BSER, and 

given the 6-year lead time (from the date of these proposed standards) until model lines 

must come into compliance with the proposed Step 2 limit, we determined that the twostep phased-in limits represent BSER for these residential consumer appliances at this 

time. Thus, we are proposing a two-step standard for hydronic heaters, in which Proposed 

Step 1 is required upon the effective date of the final rule, and Proposed Step 2 is 

required 5 years after publication of the final rule. Section V.B.5 discusses a three-step 

alternative approach that we also considered for hydronic heaters, and on which we are 

seeking comment.

b. Forced-air Furnaces

Emissions from wood-fired, forced-air furnaces have not previously received 

much attention in the U.S. However, industry information suggests that there are three 

times more sales of wood-fired, forced-air furnaces each year compared to wood-fired 

hydronic heaters. These units are relatively easy to retrofit into existing structures, and 

their sales price is substantially less than hydronic heaters. Because they are whole-house 

heating systems, they have the capacity to generate large amounts of emissions. Also,

they compete with wood-fired hydronic heaters, which we propose to regulate. Not 

regulating wood-fired, forced-air furnaces could create an adverse competitive imbalance 

with the wood-fired hydronic heater market segment.

 

60 See footnote 40.
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Wood-fired, forced-air furnaces are not currently regulated in the U.S. (with the 

exceptions of broader bans or use limits on wood-burning appliances), but they are 

beginning to be addressed in Canada. The main regulatory mechanisms are local and 

provincial regulations requiring listing per CSA B415.1-10, which is the CSA 

specification for emission performance of solid-fuel-burning heating appliances.

61 All 

CSA standards are developed through a consensus standards development process 

approved by the Standards Council of Canada. This process brings together stakeholder 

volunteers representing varied viewpoints and interests to achieve consensus and develop 

a standard. The most recent B415.1-10 Committee consisted of manufacturers, 

Environment Canada,

62 provincial agency staff, test laboratories and the EPA. The 

current version of B415.1-10 was published in March 2010, and it includes new 

requirements for indoor and outdoor central heating appliances, including wood-fired 

forced-air furnaces. In addition to establishing performance test requirements, B415.1-10

also includes emissions requirements for PM. Section 4.2.1(c) of the CSA standard 

establishes an average particulate emission rate of less than or equal to 0.40 g/MJ, which 

is equivalent to 0.928 lb/MMBtu. Manufacturers anticipate that CSA Standard B415.1-10 

will effectively establish the minimum requirements for future units sold in Canada. For 

example, the province of British Columbia has enacted regulations limiting the sale of 

wood-burning appliances to those that comply with B415.1-10 (or the U.S. NSPS), and 

 

61 CSA B415.1-10: Performance testing of solid-fuel-burning heating appliances, 

Canadian Standards Association, Mississauga, Ontario, Canada. March 2010.

62 Environment Canada was created in 1971, and has the responsibility to implement the 

Government of Canada’s environmental agenda including, but not limited to, Canada's 

environmental and wildlife legislation, enforcement activities and other efforts to protect, 

conserve and enhance the environment.
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other provinces and municipalities in Canada are in the process of amending their 

regulations to apply to central heating systems, including forced-air furnaces.

In developing the B415.1-10 emissions limit of 0.40 g/MJ (0.928 lb/MMBtu) for 

solid-fuel central heating systems, the CSA committee thoroughly reviewed the best 

systems available, developed a test method for such systems and supported emission 

testing of candidate best systems. A B415.1-10 validation-testing program performed by 

Intertek in Middleton, Wisconsin, included both a high-tech furnace and a conventional 

furnace. The high-tech furnace achieved average particulate emissions of 0.46 g/MJ 

output (1.067 lb/MMBtu). The conventional furnace achieved average particulate 

emissions of 1.65 g/MJ (3.828 lb/MMBtu) output. Thus, the CSA limit of 0.40 g/MJ 

(0.928 lb/MMBtu) output corresponds to a 75 percent reduction in emissions when using 

the average particulate emissions of the conventional furnace tested by Intertek as part of 

the CSA B415.1-10 validation program.

We also investigated the performance of European production forced-air furnace 

models to determine whether their performance might be better than what CSA found in 

North America. However, forced-air furnaces are not commonly used in Europe because 

they are considered to be an inferior technology for home heating; thus we had no 

European candidate BSER to consider. 

Manufacturers are actively conducting R&D in response to both the current CSA 

standard and the anticipated NSPS we are proposing. For example, one company has 

recently had an EPA-certified laboratory test two of their newest models. These tests, 

using the test method in CSA B415.1-10, show particle emissions below 0.1 lb/MMBtu 

heat output. Considering all of the above, we believe that BSER for forced-air furnaces 
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may be demonstrated at the same emission levels as for hydronic heaters. We have 

considered proposing standards for forced-air furnaces that match the Step 1 and Step 2

standards we are proposing for hydronic heaters, that is, a proposed Step 1 BSER of 0.32 

lb/MMBtu heat output and a cap of 18 g/hr as determined by the test methods and 

procedures in CSA B415.1-10 upon the effective date of the final standard and a 

proposed Step 2 BSER of 0.06 lb/MMBtu heat output as determined by the test methods 

and procedures in CSA B415.1-10, 5 years after the effective date of the final standard. 

However, we have concerns that only one U.S. manufacturer currently has models that 

have been tested by B415.1-10 and shown to achieve these levels, and thus, we are 

proposing that the Step 1 BSER for forced-air furnaces match the current CSA B415.1-10 

level of 0.93 lb/MMBtu heat output. We are also proposing, however, that by 5 years 

after the effective date of the final standard, forced-air furnaces be put on a level playing 

field with hydronic heaters and be required to meet the proposed Step 2 BSER of 0.06 

lb/MMBtu that hydronic heaters must meet then under this proposal.

Given that the largest U.S. forced-air furnace manufacturer already has a catalytic 

model meeting 0.06 lb/MMBtu, we think the 6 years of lead time is sufficient time in 

which to conduct R&D to produce comparably lower emitting model lines, although we 

are seeking comment on an alternative 3-step approach with a longer lead time. Since 

there are limited emissions data available for forced-air furnaces that reflect hydronic 

heater proposed Step 1 and proposed Step 2 BSER, we request specific comments and 

data on the proposed emission levels and compliance deadlines, as well as the 

environmental impacts and market implications for setting emission limits that match 

what we are proposing for hydronic heaters.
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The nationwide annualized total costs are based on the cost assumptions 

explained in section IV.C and in the background documentation.63 The average annual 

cost increase to manufacturers of forced air furnaces during the 2014 through 2022 period 

used in the RIA is approximately $2.3 million. Estimated nationwide annual PM2.5

emissions, averaged over this same period (2014-2022), are projected to be 3,044

tons/year under the baseline (unregulated) condition versus 434 tons/year under the 

proposed two-step BSER, an average reduction of 2,610 tons/year. Given these cost and 

emission estimates, the average cost of reducing each ton of PM2.5 emissions during the 

2014-2022 period is approximately $860 per ton annually. The cost-to-sales ratio is 2.4

percent. When considering the total costs and cumulative emission reductions over the 

full model design lifespan and appliance emitting lifespan however, the overall cost 

effectiveness is approximately $40 per ton (shown above in Table 11).64

Given the reasonable cost effectiveness of imposing the two-step BSER, and 

given the 6-year lead time (from the date of these proposed standards) until new model

lines must come into compliance with the proposed Step 2 limit, we determined that the 

two-step phased-in limits represent BSER for these residential consumer appliances at 

this time. Thus, we are proposing a two-step standard for forced air furnaces, in which 

Proposed Step 1 is required upon the effective date of the final rule and Proposed Step 2 

is required 5 years after the effective date of the final rule. Section V.B.5 discusses the

three-step alternative approach that we also considered for forced air furnaces, and on 

which we are seeking comment.

3. Masonry Heaters 

 

63 See footnotes 37 and 38.

64 See footnote 40.
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We are proposing subpart RRRR for masonry heaters. With a few exceptions, 

masonry heater emissions are not subject to specific PM emission limits in North 

America or Europe. Some states and local areas do not allow any residential wood 

heaters that are not certified to meet the current residential wood heater NSPS. The states 

of Colorado and Washington have set 6 grams of particles emitted per kilogram of wood 

burned (g/kg) and 7.3 g/kg limits, respectively (each of which is based on different test 

methods), and a small number of appliances have been tested and certified for those 

states. (The BSER level we are proposing below uses a different format but is commonly

accepted to be somewhat more stringent than the Colorado and Washington limits.) We 

considered various forms for a masonry heater standard, and we believe that an 

appropriate format could be a daily average g/hr limit for the heating cycle coupled with 

a limit for emissions per heat output (lb/MMBtu output). The daily average over the 

heating cycle format seems to be well adapted to the nature of the technology of masonry

heater operation, which involves one or two short high burn rate cycles where hot gases 

are generated during combustion of a fuel load in the firebox and then pass through the 

channels, saturating the masonry mass with heat. The masonry mass then radiates heat 

into the area around the masonry heater for 12 to 24 hours. Unfortunately, we lack 

sufficient data to set the level of a daily average data approach, so we are proposing 

instead a heat output format. The heat output format has the advantage of providing a 

good metric for consumers and regulatory agencies to compare emissions of competing 

residential heating appliances for an equivalent heat output. We ask for specific 

comments on whether a g/kg format would be better.
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We had numerous discussions with states, masonry heater manufacturers, and 

laboratories on heater designs, test methods and heater emissions and performance. The 

best performing improved combustion technology masonry heaters have well-engineered 

designs with long channels to maximize complete combustion and heat transfer. The 

manufacturers provided all available current emissions data. For example, one 

manufacturer has maintained an archive of available data, which he provided to us. The 

data set included results from 31 tests (measuring emissions per heat output) that ranged 

from 0.07 g/MJ to 0.51 g/MJ (~0.17 to 1.22 lb/MMBtu), with an average rate of 0.26 

g/MJ (0.621 lb/MMBtu). Looking at this data set in more detail, one can see that the best 

“improved combustion” systems have an emission level of 0.13 g/MJ (0.32 lb/MMBtu) 

heat output. We note that this level is consistent with the proposed Step 1 BSER for 

hydronic heaters. 

As discussed earlier in this preamble, the source categories to be regulated by the 

proposed subparts AAA, QQQQ, and RRRR are fundamentally different from the typical 

NSPS source category in that they include mass-produced residential consumer products 

whereas most NSPS regulate industrial processes. Thus, additional factors are included in 

the analyses presented today as compared to typical NSPS. For example, we considered 

whether we should allow longer lead time over which small manufacturers/builders could 

spread their R&D costs in order to stay in business. The Small Business Regulatory

Enforcement Act Panel strongly recommended that we consider allowing more time. See 

section V.C of this preamble for discussion of this topic. 

We estimated proposed Step 1 improved combustion BSER emissions and cost 

and economic impacts based on four groups of costs. The first group of costs consisted of 
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the two large manufacturers that we know have already developed potentially complying 

models and would only face the costs of certification tests. For the second group of costs, 

we estimated the costs incurred by an additional two large manufacturers that conduct 

R&D to develop a total of four new model lines. For the third group of costs, we 

estimated the cost of one of the manufacturers using the computer simulation approach to 

certify additional model lines. Finally, for the fourth group of costs, we estimated the cost 

for all of the small, custom-built manufacturers using the computer simulation approach 

to certify their model lines. We do not anticipate a significant quantifiable emission 

reduction resulting from requiring the proposed Step 1 BSER versus what most 

manufacturers would have done in the absence of a rule; however we believe it is 

important to ensure that all models achieve the emission levels of the BSER and avoid 

backsliding. 

The nationwide annualized total costs are based on the cost assumptions 

explained in section IV.C and in the background documentation.65 The average annual 

cost increase to manufacturers of masonry heaters during the 2014 through 2022 period 

used in the RIA is approximately $294,000. The estimated cost-to-sales ratio is 4.8

percent. If one were to spread the costs over the much longer typical lifetimes of masonry 

heaters (over 40 years), the average costs would be much lower. We concluded that the 

proposed Step 1 BSER level of 0.32 lb/MMBtu heat output is appropriate for these 

appliances because of the conservative assumptions in the original analysis and for the 

following reasons: 

 

65 See footnotes 37 and 38.
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 We agree that most masonry heater models are inherently cleaner than other types of 

wood heating systems on a daily average basis. The ability to show the EPA 

certification may allow manufacturers of certified masonry heaters access to markets 

in local jurisdictions that only allow the use of certified appliances (contingent upon 

approval by local jurisdictions).

 By giving manufacturers regulatory certainty, they will feel more confident in 

investing in testing to certify their existing and emerging systems and expanded use 

of existing designs via licensing agreements.

For masonry heaters, we are proposing that large manufacturers of masonry

heaters (defined as those manufacturers constructing 15 or more masonry heaters per 

year) would be required to comply with these standards upon the effective date of the 

final rule. We are proposing that small manufacturers (defined as those manufacturers of 

less than 15 masonry heaters per year) would be required to comply with these standards 

5 years after the effective date of the final rule. We are requesting specific comments on 

the proposed BSER option and data that might support alternative findings and enhance 

our impact analyses. For example, if we were to develop a g/hr average format in 

addition to the lb/MMBtu heat output format, are there products that might meet a daily 

average over the heating period versus the averaging only over the combustion period, 

and if so, how would this affect levels of performance and impacts on the environment?

Further, we are seeking comment on the degree to which these dates could be sooner. 

4. Alternative Approach for Comment

Please pay very close attention to the words “proposed” and “alternative” in this 

section. As noted in section III, in addition to the proposed two-step standards described 
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above for appliances regulated as “room heaters” under subpart AAA (currently catalytic 

and noncatalytic adjustable burn rate wood heaters, single burn rate wood heaters, and 

pellet heaters/stoves) and for appliances regulated as “central heaters” under subpart 

QQQQ (currently hydronic heaters and forced-air furnaces), we also considered a

different approach, an “alternative three-step approach” for subparts AAA and QQQQ. 

We seek comments on whether the final rule should be our (preferred) proposed two-step 

approach or whether the final rule should be this alternative three-step approach. We do 

not intend for the final rule to allow a choice between the two approaches. We did not 

develop a three-step approach for masonry heaters under subpart RRRR, since it is a oneemission-level standard, but we are seeking comments on our proposed 5-year 

compliance extension for small volume masonry heater manufacturers. 

We compared unit cost increases,

66 nationwide manufacturer cost estimates,67

emission reductions,

68 and overall cost effectiveness of the two-step proposal to the threestep alternative approach considered.69 Table 12 compares the unit cost increase, 

nationwide average cost to manufacturers and the annual particulate emission reductions,

during the 2014 through 2022 period used in the RIA, for appliances currently affected 

by this proposal. Based on the cost and emission reduction estimates presented in this 

table, the overall cost effectiveness for this proposal over the 2014-2022 period is $3,250 

per ton, but $5,800 per ton for the alternative approach considered (assuming no emission 

reductions for masonry heaters, for the sake of this analysis). Additional information on 

the impacts is included in the RIA in the docket.

 

66 See footnote 38.

67 See footnote 37.

68 See footnote 24.

69 See footnote 40.
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Table 12. Comparison of Proposal and Alternative Approach (2014-2022)

Appliance 

Type

Unit Cost Increase from 

Baseline (2010$)

Nationwide Average

Cost Increase from 

Baseline (2010$)

Emission Reduction from 

Baseline (tons)

Proposal Alternative Proposal Alternative Proposal Alternative

Certified 

Wood Heaters 24 48 4,212,303 8,090,026 163 136

Single Burn 

Rate Heaters 226 337 901,732 1,540,600 754 756

Pellet 

Heaters/

Stoves

24 47 3,460,489 6,255,536 49 24

Forced-Air 

Furnaces 3,262 4,891 2,252,284 3,813,898 2,610 2,712

Hydronic 

Heating 

Systems

6,458 9,672 4,554,152 8,302,026 1,249 1,250

Masonry 

Heaters 300 (ave.) 300 (ave.) 307,511 293,776 Not estimated

Not 

estimated

Total 10,294 15,295 15,688,471 28,295,862 4,825 4,878

We are seeking comment on potential justifications for implementing such a 

three-step standard, instead of our proposed two-step standard for each of the appliances 

affected by this proposed rule, to provide additional flexibility for manufacturers that 

have different capabilities and resources to ultimately reach the most stringent BSER.

The proposed two-step standards rely on the assumption that the proposed Step 2 BSER, 

already demonstrated by various models in each appliance category affected by the 

proposed rule, is achievable within 5 years of the proposed Step 1 BSER. There is a 

significant emission reduction achieved by the proposed Step 2 BSER compared to the 

proposed Step 1 BSER in each appliance category discussed above in section V, but there 

are no proposed interim emission limits imposed during the transition from the proposed 

Step 1 to the proposed Step 2. In the alternative approach considered, there is a longer 

transition period of 8 years between Step 1 and Step 3 (with the same significant 
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emission reduction achieved between our proposed Step 1 and proposed Step 2), but there 

is an interim Step 2 limit which manufacturers must comply with 3 years after the 

proposed Step 1. If we were to give a longer timeframe to redesign across model lines to 

accommodate the best systems, test, field evaluate, and certify a wide range of model 

lines, we believe there would be benefit to establishing required interim limits to codify

progress in reducing emissions and to focus positive attention on early achievers as they

show compliance in the period between 2014 and 2022.

We expect that the manufacturers that do not already meet the strongest emission 

limits would like the longer time to meet the Alternative Approach Step 3 but would 

prefer to not have an interim Step 2 requirement. However, we do not currently see 

adequate justification for allowing extra time without also requiring satisfactory progress, 

especially because numerous models already achieve the strongest emission levels. We 

also have concerns about the complexity of a 3-step approach and whether it would be 

harder for consumers to understand and for the EPA to enforce. Thus, we seek comment, 

including data and potential environmental and economic justifications, on whether the 

described Alternative Approach Step 2 emission limits represent BSER within 3 years of 

the effective date of the final rule. We also seek comment on whether an additional 5 

years would be necessary to transition from the Alternative Approach Step 2 to the 

Alternative Approach Step 3 limit, or whether such a transition could be made in a 

shorter time period. Finally, for single burn rate wood heaters and forced-air furnaces, we 

are seeking comment on whether the alternative Step 1 limit should become effective 

upon the effective date of the final rule or after a 1-year “adjustment” period. The EPA 

seeks to encourage national achievement of the (proposed Step 2) BSER for each 
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appliance category as soon as possible and as efficiently as possible, which is why we 

prefer the proposal over the alternative approach we considered. However, we also seek 

to balance industry’s research and development needs with timely and efficient standards, 

and so are seeking comment on the alternative approach outlined immediately above and 

in section III.

5. Other Proposed Emissions Testing and Reporting

a. Efficiency Testing and Reporting 

While the CAA gives the EPA authority to set standards for emissions, and we 

have issued final rules that have used a variety of formats for such standards, including 

efficiency, we lack sufficient data to propose efficiency standards at this time. We are 

proposing only to require testing and reporting but not a minimum efficiency standard. 

Current data and other information from manufacturers and testing laboratories and the 

NYSERDA “European Wood-Heating Technology Survey” discussed earlier in the

preamble show that, in general, the same types of improved combustion BSER designs 

that tend to reduce PM2.5 emissions also tend to increase combustion efficiency, reduce 

CO emissions and meet the efficiency levels proposed below. Current subpart AAA 

allows sources to either measure efficiency or report a default efficiency value. We 

believe these proposed subparts are an excellent opportunity to standardize the collection 

and reporting of such data.

Most industry members support the collection and reporting of tested efficiency

values, but some do not necessarily support an efficiency standard because they have 

concerns that efficiency standards would encourage a “ratings race” and worry that some 

manufacturers would sacrifice operational viability in the field for a higher efficiency
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rating. We agree that some heat loss is necessary so that there is adequate draft out the 

chimney/stack and not backdrafting into living areas. However, we do not expect 

manufacturers to jeopardize their reputation or operator safety for a higher rating, and we 

believe that competition among manufacturers to increase their heaters/stoves’ 

efficiencies is good for consumers and the environment. We request specific comments 

and supporting data that would help inform the need for and level of a possible efficiency

standard. Also, we ask for specific comments on how, in the meantime, to best ensure 

consumers have access to the best information on efficiency performance, e.g., labels, 

owner’s manual, Burn Wise website and/or other means.

b. CO Testing and Reporting

We considered developing CO emission limits for all appliances in the NSPS. 

However, our current data for CO emissions performance and methods of control are not 

sufficiently robust to support strong CO emission limits, and it would delay the NSPS if 

we were to seek additional data elsewhere at this time to support strong CO emission 

limits. We expect the CO emissions to be reduced as a result of the control of PM, 

because meeting the PM standards will be achieved primarily by BSER based on good 

combustion which will also result in good CO reductions without additional standards for 

CO. However, we are proposing that manufacturers measure and report CO. We believe 

this information will be useful to consumers and state and local regulators. Requiring 

manufacturers to measure and report CO emissions would also result in the collection of 

data that could be used in the future to establish a CO emissions limit. We are requesting 

specific comments and supporting data on the need for and level of a possible CO 
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emissions standard. Also, we ask for comments on whether we should require an indoor 

CO monitor because of safety concerns for appliances that are installed in occupied areas.

c. Pellet Fuel Requirements

A wide variety of pellet fuels is available for purchase. However, in some cases, 

quality claims on the pellet fuel bag do not necessarily reflect what is in the bag and there 

can be variable performance even within the same grade. In addition, some fuels have 

worse burning characteristics and operational characteristics than others, which results in 

increased emissions of PM. The PFI, an industry trade organization, has had pellet fuel 

standards in place since 1995, with updated standards issued in 2005, and again, most 

recently in 2011 (http://pelletheat.org/wp-content/uploads/2011/11/PFI-StandardSpecification-November-2011.pdf), in response to the EPA’s planned revisions to the 

residential wood heaters NSPS. We have reviewed the PFI program and believe it is a 

good program that obviates the need for the EPA to develop our own program at this 

time. Under the proposed NSPS, pellet burning appliances would be tested using PFI (or, 

upon request to the EPA Administrator, an equivalent organization’s) graded pellet 

fuel(s). Once certified, pellet burning appliances may only burn the grade of fuel that the 

appliance manufacturer chose for the appliance certification test and the manufacturer 

specifies in their owner’s manual for the operator to use. The overall intent of the 

certification process is to increase the consistency and quality of pelletized fuel 

throughout the industry, thus reducing appliance operational problems and helping 

certified appliances perform at the emission levels to which they are certified. Heater 

manufacturers have indicated to us that market competition will compel them to specify

the widest range of grades for which their heaters will properly perform. 
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The PFI is also implementing a quality assurance program to ensure that 

manufacturers reliably produce graded fuels. We propose to require adherence to this 

program (or equivalent) as a condition of producing graded pellet fuels to be used in 

obtaining certification under the NSPS. Similar to the NSPS quality assurance program, 

the PFI quality assurance program relies on use of accreditation and auditing bodies that:

 Accredit auditing agencies and testing laboratories

 Implement and enforce the program, including testing that the pellet fuels meet the 

grading specifications

 Maintain the enforcement regulations

 Administer a laboratory proficiency program

 Pursue product complaints

In addition, accredited auditing agencies perform the following tasks: 

 Certify the production of densified fuel manufacturers

 Authorize production facilities to use PFI’s “grading mark”

 Conduct regular audits and extracts samples for third party verification 

 Revoke authority to use the PFI mark, if necessary

Accredited testing laboratories perform the following activities: 

 Provide QA/QC testing for fuel producers – “as needed”

 Provide testing for samples collected by auditing agencies

 Participate in the accreditation body’s proficiency testing program

Finally, the densified fuel producers perform the following activities:

 Develop an in-house QA/QC program based on the PFI QA/QC handbook and the 

PFI standard specification
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 Select an auditing agency and test lab

 Demonstrate compliance with grading system component

 Maintain compliance through periodic audits, inspection and testing

As noted earlier, we have reviewed the PFI program and believe it is a good 

program that obviates the need for the EPA to develop our own program at this time. We 

ask for specific comments on this decision and the PFI program. 

d. Prohibited Fuel Types

As regulated in the current subpart AAA standards for residential wood 

heaters/stoves, operation according to the owner’s manual requires operation with the 

appropriate fuels because the choice of fuels to burn in any appliance can have a major 

impact on emissions and efficient operation of the appliance. For clarity, we are 

proposing to add a list of prohibited fuel types (e.g., trash, wood treated with creosote, 

animal waste) to the wood-burning NSPS subparts to emphasize the responsibility of 

owners and operators to use appropriate fuels that will result in the performance of the 

unit as certified, to avoid the creation of possibly hazardous fumes from burning 

inappropriate materials, and to ensure that appliance continues to operate as designed. 

Even with burning clean wood, one of the key factors affecting emissions is the moisture 

content. Some advocates have suggested that we only allow use of wood certified to a 

certain moisture level and that we include visible emission limits as a tool to help with 

practical enforceability of the requirements for proper operation and maintenance. 

Manufacturers typically include in their owner’s manuals information on proper 

maintenance and operation and state that the wood must be properly seasoned so that the 

moisture content is not too high for proper operation. Some manufacturers include 
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moisture meters for the operators. We are proposing to require commercial owners (direct 

distribution manufacturers and retailers) to provide a moisture meter with the wood 

heater at the time of sale, along with the owner’s manual and a copy of the warranty. We 

request specific comments on whether we should include more specific requirements on 

proper operations, such as the moisture content of the wood and visible emission 

limitations.

C. How did we establish the proposed compliance timelines? 

The following table summarizes the proposed compliance timelines for the 

appliances covered by the three subparts.

Table 13. Summary of Proposed Compliance Dates70

Appliance Type BSER Compliance Date

Adjustable Rate Wood Heaters or 

Pellet Heaters/Stoves with Current 

EPA Certification Issued Prior to the 

Effective Date of the Final Rule 

(Upon the effective date of the final rule)

1988 requirements remain in effect for 

these heaters/stoves through the later of 

the effective date of the final revised rule 

or expiration of current certification 

(maximum of 5 years after certification 

and no renewal)

All Other Adjustable Rate Wood 

Heaters or Pellet Heaters/Stoves 

(includes currently certified heaters 

after the certification expires)

Step 1: “2014” (upon the effective date 

of the final rule)

Step 2: “2019” (5 years after the effective 

date of the final rule)

Single Burn Rate Heaters Step 1: “2014” (upon the effective date 

of the final rule)

Step 2: “2019” (5 years after the effective 

date of the final rule)

Hydronic Heaters Step 1: “2014” (upon the effective date 

of the final rule)

Step 2: “2019” (5 years after the effective 

date of the final rule)

 

70 “Year” based on estimated publication of final rule in 2014. If the publication date 

changes, the EPA will change the compliance dates based on the actual date of 

publication.
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Forced-Air Furnaces Step 1: “2014” (upon the effective date 

of the final rule)

Step 2: “2019” (5 years after the effective 

date of the final rule)

Masonry Heaters Step 1: “2014” (upon the effective date 

of the final rule) for large manufacturers

Step 2: “2019” (5 years after the effective 

date of the final rule for small 

manufacturers)

All of the proposed compliance dates are tied to the effective date of the final 

standards. For example, the “2014” dates refer to the approximate effective date of the 

final rule. As stated earlier, an element of the BSER determination includes reasonable 

lead time for R&D to develop and certify cleaner units. We are proposing the “2014” 

limits because we think limited or no R&D is needed to comply with the proposed Step 1 

BSER standards. This allows manufacturers approximately 1 year between the date of 

this proposal and the date of the final rule to meet proposed compliance standards and 

limits. This 1-year period is in addition to the time that manufacturers have had leading 

up to this proposed rule.

We allowed small producers of masonry heaters that do not have a history of 

federal or extensive state regulation, or experience with voluntary partnership programs,

5 years after the effective date of the final rule, “2019,” to come into compliance with the

same emission standards as larger masonry heater manufacturers in order to ensure a 

reasonable lead-time.

Finally, we think our proposal for a 6-year lead time before the Step 2 BSER 

limits in “2019” (i.e., 5 years after the effective date of the final rule) would allow 
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manufacturers a reasonable time to develop complying models, access the necessary

capital to develop them, and complete the certification process. 

We are proposing a 6-month “sold at retail” provision for adjustable burn rate 

wood heaters, single burn rate heaters/stoves, and pellet heaters/stoves that were 

manufactured prior to the effective date of the final rule, but not yet sold. This “sold at 

retail” provision is similar to that provided in the current subpart AAA, and provides a 

reasonable transition for manufacturers to recoup their investment in their stock on hand. 

We believe this provision would have a nominal impact on air quality, because the 

majority of these appliances are already expected to achieve the 2014 standards. In the 

case of small producers of masonry heaters, we are proposing an additional 5-year leadtime for compliance. We are not proposing to apply these extensions to other sources 

regulated by this proposal. We do not believe that an additional “sold at retail” provision 

is needed outdoor and indoor hydronic heaters and forced-air furnaces. In the case of 

hydronic heaters, we believe that any delay of the compliance deadline for sales would 

also result in the sale and long-term use of non-complying units, with a potentially

adverse quality impact. We request specific comments on whether there are other factors 

we should consider regarding this “sold at retail” window and what length of time might 

be considered appropriate in specific circumstances.

While the original subpart AAA created a 1-year compliance extension for wood 

heater manufacturers producing less than 2,000 heaters per year, this proposed rule does 

not include a compliance extension provision for single burn rate heaters. The purpose of 

the original NSPS compliance date extension was to reduce the potential for a testing 

logjam and to provide small manufacturers additional time to conduct R&D, obtain 
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financing, or purchase complying designs likely to meet the proposed standards. We 

believe that manufacturers and testing facilities have now had sufficient time and have 

gained the expertise necessary to meet these standards as proposed and that meeting the 

proposed compliance dates will impose no undue imposition on manufacturers or testing 

facilities. We request comment on the need for such a compliance extension and the 

number of models that might qualify as a small single burn rate heater manufacturer.

As stated above, we are proposing a 5-year compliance date extension for 

masonry heater manufacturers that sell fewer than 15 units per year. We also seek 

comments on whether we should have a cap on the total units sold in the 5 years, perhaps 

50 units. Most of these manufacturers are very small companies. There are only a few 

major producers. According to one manufacturer, the Finnish firm, Tulikivi, 

manufactures and supplies about one-half of the U.S. masonry heater units installed 

yearly through its network of installing distributors. The second largest producer is a 

Canadian firm, Temp-Cast, which manufactures and exports a large percentage of the 

remainder as internal core components only to U.S. dealer/installers and homeowners. 

This manufacturer states that the remainder of the industry is dozens of small producers 

and installers who produce only a few units, most of which are custom and individually

designed. This manufacturer also stated that over 80 percent of U.S. masonry heater 

installations use manufactured core product installation and are not custom site built 

(brick-by-brick).

Because of the resources required to develop, test, and certify masonry heaters 

(estimated by industry to be approximately $250,000 per model, although our cost 

analysis used a larger, more conservative estimate), we have concluded that a 
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manufacturer of a small number of custom site-built model(s) of masonry heaters would 

likely be unable to recover the total cost of R&D and certification testing costs in a 

reasonable timeframe. Similarly, a company that makes core components or sells design 

kits would be unable to recover total costs if only a few such components or kits are sold 

per year. We estimated that the annualized cost for developing, testing and certifying a 

single model is approximately $60,000, most of which is the cost of R&D. If a seller 

makes $5,000 of profit on each model sold, he or she would need to sell 12 units per year 

to break even. The masonry heater industry recognized concerns about these costs, and it 

has developed an alternative compliance method based on computer simulations. The 

industry expects that this alternative will allow sharing licensing of cleaner designs such 

that the initial software purchase would cost approximately $1,500 but ongoing annual 

licensing cost will be approximately $450 per manufacturer. We believe the 5-year 

compliance date extension discussed above for masonry heater manufacturers that sell 

fewer than 15 units per year will allow sufficient time for manufacturers to become 

comfortable with this alternative, and use it to demonstrate compliance.

We considered proposing a compliance exemption for small manufacturers of 

masonry heaters because of the overall small size of the market. However, we were 

concerned that this might encourage installation of cheaper, low-performing models, 

which would place complying models at a potential disadvantage. We request comment 

on the need for either a compliance date extension or a compliance date exemption for 

masonry heaters and the length of time that we should allow.

We are not proposing any extensions or exemptions for small manufacturers of 

adjustable burn rate wood heaters or pellet heaters/stoves. Adjustable burn rate wood 
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heaters are already subject to the NSPS, and we have estimated that they should not face 

any R&D expenses to comply with the “2014” standards. To reduce unnecessary

certification costs, we are proposing to allow a one-time waiver from performance testing 

for the first certification period for any manufacturer that has previously conducted a 

valid certification test that demonstrates the wood heaters in the model line meet the 

proposed standards. We also believe that pellet heaters/stoves would not face any R&D 

costs to comply with the proposed “2014” standards, and we estimate that certification 

costs will only pose a minor impact. We request comment on whether there are other 

factors we should consider regarding a small manufacturer compliance extension for 

these appliances.

We also are not proposing a small manufacturer compliance extension for the 

“2014” standards for new residential hydronic heaters or forced-air furnaces. There are 

currently 36 hydronic heater models built by 17 U.S. manufacturers that have already 

been qualified to meet the Phase 2 voluntary partnership program level of 0.32 lb/MM 

BTU. Manufacturers of hydronic heaters and forced-air furnaces have known for several 

years that we were drafting this proposal and that the states have been very concerned 

about emissions from the models that may not meet the proposed standards; and we do 

not want to perpetuate sales and use of models unless they demonstrate they do meet the 

standards. Once again, we request comment on whether there are other factors we should 

consider regarding a small manufacturer compliance extension for these appliances and 

what number of appliances sold would constitute a small volume manufacturer.

As discussed above, we recognize there is some concern, as there was with the 

initial NSPS compliance dates, that testing laboratories may not be able to meet the 
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demand for certification tests in the first few years. However, we believe that the steps 

we have already proposed, the availability of additional ISO-accredited labs, the advance 

notice that industry has had concerning the NSPS prior to this proposal, and the time 

between this proposal and the proposed compliance date of the final rule, should ensure 

that adequate compliance certification resources are available. The logjam provisions of 

the current 1988 NSPS were never invoked, and we do not think they are needed at this 

time. However, we are taking comment on this issue. We also request comment on 

whether these compliance timelines strike the right balance between avoiding undue 

economic burdens and the need to get better performing models on the market as soon as 

possible to reduce emissions, and whether other compliance dates would be appropriate.

D. How are we proposing to streamline the requirements for certification, quality 

assurance and laboratory accreditation?

As part of the NSPS review process, several stakeholders stated the need to 

improve the current certification and quality assurance requirements. For example, some 

pellet heaters/stove manufacturers said one reason they avoid certifying their 

heaters/stoves is because they are concerned that the current process is a barrier to rapid 

product development and making changes to respond to market demand. Many 

manufacturers were also concerned that, as the scope of the NSPS program expands to 

include multiple appliance types, the certification program would act as a logjam. Some 

states are concerned, however, that moving away from the EPA certification might result 

in less effective oversight. At the EPA, we are also looking for ways to use our 

enforcement resources more effectively. 
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We believe that the proposed changes, described in section III.A regarding a 

third-party certification program by an ISO-accredited certifying body and testing at ISOaccredited labs, will facilitate the development of improved designs by providing a faster 

approval process and reducing redundancies in quality assurance for emissions testing 

and safety testing, and will improve enforcement by providing for more frequent on-site 

inspections of manufacturing facilities and laboratories. For example, safety certification 

audits take place quarterly and include the random inspection of manufactured units for 

compliance with design and safety factors. The experience of the voluntary partnership 

programs ISO process has shown that the third-party approach can work.

We also reviewed the list of design changes (the “k” list; See 40 CFR, subpart 

AAA, §60.633(k) ) that would result in a need to recertify a model line when certain 

tolerances are exceeded. We reviewed this list based on the experience we have to date 

on the types of changes that are significant and knowledge about current manufacturing 

processes that help prevent these changes from occurring. The resulting list focuses on 

the following key tolerances: 

 Firebox dimensions 

 Air introduction systems

 Dimensions and locations of the baffle, catalyst, refractory/insulation, flue gas exit, 

and the outer shielding and covering

 Dimensions and fit of the gaskets for the door and catalyst bypass

 Fuel feed system

 Forced air combustion system
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We believe these changes will focus resources on the significant changes that 

could affect emissions performance of the model in question. We ask for specific 

comments on this list and the level of appropriate tolerances.

We propose to revise the requirement for manufacturers to conduct quality

assurance emission tests once a specified number of units are sold. Instead, we propose to 

replace this numerical trigger with a requirement to retest when manufacturer-specific 

quality assurance criteria (e.g., multiple errors in safety tests) are exceeded. We believe 

that development of a manufacturer–specific quality assurance plan with specific criteria 

and approval by an ISO-accredited certifying body (or EPA-approved equivalent) and 

required follow-up by that certifying body is a more direct measure of possible 

performance issues, but we request comment on the exact event(s) that should be used as 

the trigger(s) to retest and whether the triggering event(s) should vary by appliance type.

We are proposing to retain final EPA approval of the certification, and we also 

propose to require the manufacturer to submit with the application for certification a 

statement signed by a responsible official that the manufacturer has complied with all 

requirements of the subpart and that the manufacturer understands that he or she remains 

responsible for compliance regardless of noncompliance by the certifying body. We 

believe this combination of requirements would provide meaningful EPA oversight, 

assign clear lines of responsibility, and free up resources to do more on-site inspections 

and other quality assurance activities, such as addressing issues of counterfeit certificates 

or absence of certificates. 

The current random compliance certification testing program is considered 

underused by many. The EPA recognized this and has recently initiated such testing. 
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A key element of the current 1988 NSPS laboratory audit program is the “round 

robin” test program. In this program, the EPA purchases a wood heater and sends it to 

each of the accredited laboratories to conduct emissions tests (two runs at each burn rate 

for a total of eight runs). The EPA then compares the results to determine inter-laboratory

performance. The EPA recognizes that we have not given this program as much attention 

as was envisioned in 1988. Thus, we propose to strengthen this program by specifying 

that every laboratory conducting certification tests under the NSPS must participate in the 

round robin tests every other year. If a lab’s results are not within ±10 percent of the 

value at which the heater was certified, then the lab must conduct another 8 runs. Also, 

we will remind the manufacturers that, as always, the EPA may potentially use this 

information to help determine the need for manufacturer audits and potential enforcement 

actions. We think that these requirements and reminders, combined with the proposed 

changes in test methods (described in greater detail in the test methods discussion in this 

preamble) and implementation of the ISO process will help improve inter-laboratory

repeatability and reproducibility.

E. What changes and additions to the allowed test methods are we proposing? 

As described earlier in this preamble, we are proposing changes to the test 

methods required by subpart AAA. We are also proposing test methods for the new 

subparts QQQQ and RRRR (as described earlier). In addition, we are proposing new 

requirements for testing and ultimately certifying using cord wood, which is what the 

consumer burns. All affected devices required to be tested using Method 28 or Method 28 

WHH would now be required to conduct such tests using crib wood and cord wood. 

Under Proposed Step 1, manufacturers would have the option of selecting which of these 
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test results to use to show compliance with the emissions standards. In other words, we 

are proposing to require manufacturers to conduct two separate tests, one with crib wood

and one with cord wood. We are also proposing that manufacturers be required to report 

the results of both tests to the EPA, but manufacturers can choose to certify with either 

crib or cord wood under Proposed Step 1. Under Proposed Step 2, manufacturers would 

be required to show compliance testing with cord wood.

We are also proposing to revise the test methods to require the addition of 1-hour 

filters for each test run to gather data regarding start-up and anticipated peaks. Further, 

we are proposing new compliance requirements in 2019 with emissions limits at the 

lowest burn rate (Category 1) and the maximum burn rate (Category 4), not a weighted 

average of the four burn rates, as in the current 1988 NSPS.

Based on the extensive consensus development process, history of the subpart 

AAA NSPS and hydronic heater voluntary partnership program emission test experience, 

and review of similar international standards, we believe the proposed methods reflect 

state-of-the-art test methods. However, we request specific comment on test method 

related issues and any data supporting such issues or concerns.

F. What other changes and additions to the administrative requirements are we 

proposing?

Consistent with Executive Order 13563: Improving Regulation and Regulatory

Relief, we reviewed the entire current subpart AAA to identify information that is no 

longer relevant or useful and removed associated reporting and recordkeeping 

requirements. For example, because of the changes in the audit procedures, we do not 

believe it is necessary for manufacturers to keep records of the number of affected 
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appliances that are sold each year, by certified model lines, for purposes of these 

subparts.

The prohibitions section in each of the proposed subparts (§§60.538, 60.5480, 

60.5492) is based substantially on the current prohibitions section in subpart AAA. 

Similarly, the delegation section in each proposed subpart (§§60.539a, 60.5482, 60.5494) 

is based on the current delegation section in subpart AAA. In general, we believe these 

delegations have worked well and are still appropriate with some clarifications and 

additions. The intent of the prohibitions section is to clarify the responsibility of owners 

and operators and manufacturers to comply with the proposed subparts. Key provisions 

for owners and operators emphasize that appliances must be operated in accordance with 

the owner’s manual and the appliances must not be altered in any way to circumvent the 

design and operation of a certified appliance. Key provisions for manufacturers 

emphasize the importance of complying with the label requirements and the need to 

maintain current certification for all heaters that are offered for sale. The intent of the 

delegation section is to clarify the regulatory provisions for which the EPA has retained 

sole enforcement authority (definitions, compliance and certification, test methods and 

procedures, laboratory accreditation, reporting and recordkeeping, revocation of 

certification, and hearings and appeals procedures). However, we have proposed to 

include the ability to delegate provisions to state, local or tribal agencies where local 

enforcement is essential, such as enforcement of permanent labels and owner’s manual 

content; and presentation of false or misleading information. Note that when the EPA 

“delegates” enforcement authority, we retain our authority to enforce while allowing the 

delegates also to be able to enforce the delegated provisions.
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We are proposing to replace the current subpart AAA hearing and appeal 

procedures with a streamlined Petition for Review process and also use this process in 

subparts QQQQ and RRRR. This process would allow accredited laboratories and 

manufacturers to contest audit test findings, laboratory accreditations, certification 

denials, and certification revocations by submitting a written request and supporting 

documentation to the EPA. This process would allow for expedited review and 

resolution. We request specific comments on this proposed process and other ways to 

improve or streamline procedures while preserving the integrity of the program.

VI. Statutory and Executive Order Reviews 

A. Executive Order 12866: Regulatory Planning and Review and Executive Order 

13563: Improving Regulation and Regulatory Review

Under Section 3(f)(1) of Executive Order 12866 (58 FR 51735, October 4, 1993), 

this action is an "economically significant regulatory action” because it is likely to have 

an annual effect on the economy of $100 million or more or adversely affect in a material 

way the economy, a sector of the economy, productivity, competition, jobs, the 

environment, public health or safety, or state, local, or tribal governments or 

communities. The $100 million threshold can be triggered by either costs or benefits, or a 

combination of them. Accordingly, the EPA submitted this action to OMB for review 

under Executive Orders 12866 and 13563 (76 FR 3821, January 21, 2011) and any 

changes made in response to OMB recommendations have been documented in the 

docket for this action.
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In addition, the EPA prepared an analysis of the potential costs and benefits 

associated with this action. This analysis is contained in the RIA for this proposed rule. A 

copy of the analysis is available in the docket for this action.

A summary of the monetized benefits and net benefits for the proposed rule at 

discount rates of 3 percent and 7 percent is in Table 8 of this preamble, and a more 

detailed discussion of the benefits is found in section IV.B of this preamble. For more 

information on the benefits analysis, please refer to the RIA for this rulemaking, which is 

available in the docket.

B. Paperwork Reduction Act

The information collection requirements in this proposed rule have been 

submitted for approval to OMB under the Paperwork Reduction Act, 44 U.S.C. 3501 et 

seq. Information Collection Request (ICR) documents have been prepared for each 

proposed subpart. The subpart AAA ICR has been assigned the EPA ICR number 

1176.10, which is a revision of the currently approved ICR number 1176.09. The subpart 

QQQQ ICR is a new collection, which has been assigned the EPA ICR number 2442.01. 

The subpart RRRR ICR also is a new collection, which has been assigned the EPA ICR 

number 2443.01. The new information collection requirements are not enforceable until 

OMB approves them.

The proposed rules would require manufacturers of new residential wood heating 

devices to submit applications for certification of model lines, to submit results of 

emissions tests conducted to demonstrate that the model lines would comply with the 

standards and produce certified units according to a quality control plan approved by an 

independent certifying body. Manufacturers must submit a notification of the initial test 
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and biennial reports that each certified model line remains unchanged. They must also 

maintain records of all certification data, maintain results of quality assurance program 

inspections and emissions test data, and seal and store the tested appliance. 

Consistent with the current ICR for subpart AAA, we have included costs to 

manufacture and apply permanent labels (for all models) on each applicable unit prior to 

sale. These labels provide important compliance information to enforcement officials.

Test laboratories that want to conduct NSPS certification testing would need to 

apply for accreditation, conduct initial and biennial proficiency testing and report the 

results of all such testing. Accredited test laboratories would also be required to 

participate in a random audit compliance program. Finally, the accredited laboratories 

must maintain records of all certification tests, proficiency tests and random compliance 

audit test data.

The required notifications are used to inform the agency when a new model line is 

expected to be tested. The EPA may then observe the testing operation, if desired. 

Emissions test reports are needed as these are the agency’s record of a model line’s initial 

capability to comply with the emission standard, and serve as a record of the operating 

conditions under which compliance was achieved.

Adequate recordkeeping and reporting are necessary to ensure compliance with 

these standards as required by the CAA. The information collected from recordkeeping 

and reporting requirements is also used for targeting inspections and is of sufficient 

quality to be used as evidence in court. As discussed earlier, we have reviewed all the 

current requirements and are proposing to remove the portions of the recordkeeping that 

are not necessary.
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The estimated burden for proposed subpart AAA is based on an estimated 72 

respondents (66 manufacturers and 6 testing laboratories) that would be subject to the 

rule. The number of total annual responses for subpart AAA is estimated at 265. The 

annual burden for this information collection averaged over the first 3 years of this ICR is 

estimated to be a total of 6,489 labor hours per year at a total labor cost of $516,188 per 

year. The ICR estimates that capital and the associated operation and maintenance 

(O&M) costs for these systems would be $1,452,177 per year. The average annual labor 

burden per response is 24 hours.

The estimated burden for proposed subpart QQQQ is based on an estimated 41 

respondents (37 manufacturers and 4 testing laboratories) that would be subject to the 

rule. The number of total annual responses for subpart QQQQ is estimated at 67. The 

annual burden for this information collection averaged over the first 3 years of this ICR is 

estimated to be a total of 2,134 labor hours per year at a total labor cost of $169,745 per 

year. The ICR estimates that capital and operation and maintenance (O&M) costs would 

be $715,796 per year. The average annual labor burden per response is 32 hours.

The estimated burden for proposed subpart RRRR is based on an estimated 48

respondents (45 manufacturers and 3 testing laboratories) that would be subject to the 

rule. The number of total annual responses for subpart RRRR is estimated at 108. The 

annual burden for this information collection averaged over the first 3 years of this ICR is 

estimated to be a total of 2,044 labor hours per year at a total labor cost of $162,589 per 

year. The ICR estimates that capital and operation and maintenance (O&M) costs would 

be $89,037 per year. The average annual labor burden per response is 19 hours. Burden is 

defined at 5 CFR 1320.3(b).
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An agency may not conduct or sponsor, and a person is not required to respond to, 

a collection of information unless it displays a currently valid OMB control number. The 

OMB control numbers for the EPA's regulations in 40 CFR are listed in 40 CFR part 9.

To comment on the agency's need for this information, the accuracy of the 

provided burden estimates, and any suggested methods for minimizing respondent 

burden, the EPA has established a public docket for this rule, which includes this ICR, 

under Docket ID number EPA-HQ-OAR-2009-0734. Submit any comments related to the 

ICR to the EPA and OMB. See ADDRESSES section at the beginning of this notice for 

where to submit comments to the EPA. Send ICR-related comments to OMB at the 

Office of Information and Regulatory Affairs, Office of Management and Budget, 725 

17th Street, NW, Washington, DC 20503, Attention: Desk Office for EPA. Since OMB is 

required to make a decision concerning the ICR between 30 and 60 days after [INSERT 

DATE OF PUBLICATION IN THE FEDERAL REGISTER], a comment to OMB is 

best assured of having its full effect if OMB receives it by [INSERT DATE 30 DAYS 

FROM DATE OF PUBLICATION IN THE FEDERAL REGISTER]. The final rule 

will respond to any OMB or public comments on the information collection requirements 

contained in this proposal.

C. Regulatory Flexibility Act

The Regulatory Flexibility Act (RFA) generally requires an agency to prepare a 

regulatory flexibility analysis of any rule subject to notice and comment rulemaking 

requirements under the Administrative Procedure Act or any other statute unless the 

agency certifies that the rule will not have a significant economic impact on a substantial 
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number of small entities. Small entities include small businesses, small organizations and 

small governmental jurisdictions.

For purposes of assessing the impacts of this proposed rule on small entities, 

small entity is defined as: (1) a small business that is primarily engaged in manufacturing 

heating equipment (except electric and warm air furnaces), such as heating boilers

(heaters), heating stoves, floor and wall furnaces, and wall and baseboard heating units, 

as defined by NAICS code 333414 with fewer than 500 employees, or is primarily

engaged in manufacturing air-conditioning and warm air heating equipment as defined by 

NAICS code 333415 with fewer than 750 employees, or is primarily engaged in masonry

contracting, as defined by NAICS code 238140 with annual receipts less than 14 million 

dollars (based on Small Business Administration size standards); (2) a small 

governmental jurisdiction that is a government of a city, county, town, school district or 

special district with a population of less than 50,000; and (3) a small organization that is 

any not-for-profit enterprise which is independently owned and operated and is not 

dominant in its field.

Pursuant to section 603 of the RFA, the EPA prepared an initial regulatory

flexibility analysis (IRFA) that examines the impact of the proposed rule on small entities 

along with regulatory alternatives that could reduce that impact. The IRFA contained 

within the RIA for this proposed rule is available for review in the docket and is

summarized below: 

 Reason Why Action Is Being Considered. As discussed earlier in this preamble, this 

proposal was developed following CAA section 111(b)(1)(B) review of the existing 

residential wood heater NSPS.
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 Statement of Objectives and Legal Basis of Proposed Rule. As discussed earlier in 

this preamble, the EPA is proposing to amend Standards of Performance for New 

Residential Wood Heaters and to add two new subparts: Standards of Performance for 

New Residential Hydronic Heaters and Forced-Air Furnaces and Standards of 

Performance for New Residential Masonry Heaters. This proposal would achieve

several objectives, including applying updated emission limits that reflect BSER; 

improving coverage of the broad suite of residential wood heaters; improving the test 

methods; and streamlining the certification process. This proposal does not include 

any requirements on heaters that are solely fired by gas or oil. This proposal does not 

affect existing heaters. This proposal was developed under the authority of CAA 

section 111. 

 Description and Estimate of the Number of Small Entities. As discussed earlier in this 

preamble, small entities that the EPA anticipates being affected by this proposal

would include almost all manufacturers of residential wood heaters. We estimate that 

roughly 250–300 U.S. companies manufacture residential wood heaters. We believe 

that approximately 90 percent of these manufacturers meet the SBA small-entity

definition of having fewer than 500 employees. 

 Description of reporting, recordkeeping and other compliance requirements. The 

reporting and recordkeeping requirements are described in the section immediately 

above (B. Paperwork Reduction Act). As discussed there, the information collection 

requirements (ICR), including reporting and recordkeeping, in this proposed rule have 

been submitted for approval to OMB under the Paperwork Reduction Act, 44 U.S.C. 

3501 et seq. For subpart AAA, we estimated the potential annual burden averaged 
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over the first 3 years of the ICR to be a total of 6,489 labor hours per year at a total 

labor cost of $516,188 per year and an average annual labor burden per response of

24 hours. For subpart QQQQ, we estimated 2,134 labor hours per year at a total labor 

cost of $169,745 per year and an average annual labor burden per response of 32

hours. For subpart RRRR, we estimated 2,044 labor hours per year at a total labor 

cost of $162,589 per year and an average annual labor burden per response of 19 

hours. 

 Description of other compliance requirements. As described earlier in this preamble, 

this proposal would apply updated emission limits that reflect the current best systems 

of emission reduction and improve the coverage of the expanded variety of types of 

residential wood heaters. We estimate the proposed NSPS’s total annualized average 

nationwide costs would be $15.7 million ($2010) over the 2014 through 2022 period. 

The economic impacts for industries affected by this proposed rule over this same 

period range from 4.3 percent for manufacture of wood heater/stove models to as 

much as an 6.4 percent compliance cost-to-sales estimate for manufacture of single 

burn rate wood heater models. These impacts do not presume any pass-through of 

impacts to consumers. With pass-through to consumers, these impact estimates to 

manufacturers will decline proportionate to the degree of pass-through. We estimate 

that small entities will have annualized costs of greater than 1 percent of their sales in 

all industries except NAICS 332510, 333414 and 423720 with fewer than 20 

employees, and NAICS 236115, 238140 and 442299 with receipts less than $10 

million. Those establishments in NAICS 332510, 333414 and 423720 with cost-toreceipt ratios higher than 1 percent account for 80 percent of small entities affected in 
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these industries. Establishments in NAICS 236115, 238140 and 442299 with cost-toreceipt ratios higher than 1 percent account for 99 percent of small entities affected in 

these industries.

 Relevant federal rules that may overlap or conflict with this proposal. There are no 

other relevant federal rules.

 Significant alternatives. The significant alternatives to this proposal, especially those 

that might minimize potential impacts on small entities, are presented in the 

remainder of this section.

As required by section 609(b) of the RFA, as amended by the Small Business 

Regulatory Enforcement Fairness Act (SBREFA), the EPA also convened a Small 

Business Advocacy Review Panel to obtain advice and recommendations of 

representatives of the small entities that potentially would be subject to the rule's 

requirements. The following paragraphs describe the process, the type of small entity

representatives, the outreach efforts and the Panel members. 

Even before beginning the formal SBREFA process, the EPA actively engaged in 

outreach with HPBA and many of their member companies to discuss the rule under 

development and to provide these contacts with an early opportunity to ask questions and 

discuss their concerns.71 The EPA provided each small business with general information 

on the SBREFA process and background information on the NSPS rulemaking process 

and current schedule.

 

71 Also, as noted in this preamble in the discussion of development of the hydronic heater 

emission limits, the EPA worked with the hydronic heater industry to develop a voluntary

partnership program to encourage manufacture of cleaner models, 

www.epa.gov/burnwise/participation. 
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Based on consultations with the Small Business Administration, and resulting 

from solicited self-nominations, we prepared a list of 30 potential Small Entity

Representatives (SERs), from residential wood heating appliance manufacturers (wood 

heaters, pellet heaters/stoves, hydronic heaters, forced-air furnaces and masonry heaters), 

other wood-burning appliance manufacturers (fireplaces, cookstoves), equipment 

suppliers, chimney sweeps, test laboratories, masons and trade associations. Once the 

pre-Panel process began and potential SERs were identified, the EPA held an outreach 

meeting with the potential SERs and invited representatives from the Office of Advocacy

of the Small Business Administration (OA/SBA) and the Office of Information and 

Regulatory Affairs within the Office of Management and Budget (OIRA/OMB) on June 

29, 2010, to solicit their feedback on the upcoming proposed rulemaking. Representatives 

from 26 of the 30 companies and organizations that we selected as potential SERs for this 

SBREFA process participated in the meeting (in person and by phone). At that meeting,

the EPA solicited written comments from the potential SERs, which were later 

summarized and shared with the panel as part of the convening document.

The SBAR Panel convened on August 4, 2010. The panel consisted of 

representatives of the EPA, OA/SBA and OIRA/OMB. The panel held a formal outreach 

meeting/teleconference with the SERs on August 25, 2010. To help the SERs prepare for 

this meeting, on August 11, 2010, the panel sent a list of questions, preliminary cost 

information and other materials to each of the SERs via email. Additional materials were 

emailed to the SERs on August 19, 2010. The panel provided the opportunity for 

questions and comment during the meeting on various aspects of the proposal being 

developed, including the expanded scope of the rule, changes to the current requirements 
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under consideration, preliminary cost information and follow up from the June 29, 2010, 

meeting on the SERs’ ideas for regulatory flexibility. During the August 25 meeting, 

SERs voiced general support for the planned proposed rule and shared specific concerns 

with the Panel members. As a result of this meeting, the EPA received many useful 

verbal comments, and the EPA received many helpful written comments by September 

10, 2010. 

Consistent with the RFA/SBREFA requirements, the panel evaluated the 

assembled materials and small-entity comments on issues related to elements of the

IRFA. A copy of the panel final full report is included in the docket for this proposed 

rule. We invite comments on the report. A summary of the panel recommendations is 

presented below. We have attempted to follow the panel’s recommendations to the 

degree we can while also ensuring that the options are practicable, enforceable, 

environmentally sound and consistent with the CAA. For those recommendations not 

adopted by the Agency, we have included an explanation for why we rejected them.

Many of the SERs and the Panel had concerns about the breadth of this 

rulemaking and the challenges the EPA faces in conducting rulemaking for all of these 

source categories at one time and the challenges that the small businesses will face in 

having to comply with standards for all of these source categories at one time. The panel 

recommended that the EPA should consider focusing efforts first on emissions sources 

that have the greatest potential to impact public health through the magnitude of 

emissions and population exposure. The EPA has focused our efforts. The panel noted 

the adverse effects of the 1988 NSPS on numerous wood heater/stove manufacturers, and 

the need to carefully develop a rule that will minimize business closures, while still 
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achieving significant emission reductions. All panel members believed that the EPA had 

adequate information to move forward with developing revisions that apply to the 

residential wood heater categories that are already regulated by the 1988 NSPS. 

However, two panel members recommended that the EPA Administrator consider taking 

more time to collect additional information to better determine BSER for the certified 

wood heater category. They concluded that the EPA did present to the panel enough 

information to justify regulation of this category, but the EPA did not adequately inform 

the SERs about the other categories. These two panel members believed it was unclear 

whether adoption of a more stringent standard for new sources will slow the adoption of 

new, cleaner burning heaters, potentially delaying improvements in air quality. The two 

panel members further believed, based on the information available from the EPA and the 

SERs at that time, that they could not conclude that a nationwide NSPS limit on the other 

categories would be the preferred approach for reducing wood heater emissions. 

Following the Panel’s convening on August 4, 2010, the EPA collected additional 

information, and we refined the economic and technical analyses based, in part, on input 

from the SERs as the basis for this proposal. The panel recommended that the EPA 

Administrator consider assessing the availability of data to better characterize each 

source category prior to considering proposal of standards. In particular, the panel 

recommended that the EPA consider characterizing the emissions per unit, operating 

hours per year, and the distribution of emissions across the unit types within each 

category under discussion at that time to better understand the magnitude of emissions 

reductions that may or may not be reduced through alternative regulatory and non-
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regulatory mechanisms. As discussed earlier, the EPA has considered such 

characterizations and alternatives.

The following is a list of panel recommendations and how we incorporated them 

into this proposal:

 The Panel recommended that the EPA should consider focusing efforts first on 

emissions sources that have the greatest potential to impact public health through the 

magnitude of emissions and population exposure. This proposal focuses on those 

sources.

 The Panel encouraged the EPA to consider flexibilities that will most directly

minimize the small business burdens, for example delayed compliance dates for low 

volume production. The delayed compliance approach was predicated on the concept 

that it will take a number of years for manufacturers to recover the costs of the R&D 

investment in order to achieve compliance. This proposal has incorporated a stepped 

approach for emission limits and asks for comments on other alternative approaches.

 The Panel recommended that the EPA consider the availability and feasibility of 

certification, testing labs, testing standards and other requirements. In particular, the 

Panel recommended that the EPA consider ways to streamline compliance 

certification, identifying flexible approaches and procedures that will reduce the 

burden and time for manufacturers to complete the application, testing and approval 

process for new model lines. For example, the Panel recommended that the EPA 

consider allowing the use of International Standards Organization (ISO)-accredited 

laboratories and certifying bodies to expand the number of facilities that would be 

required for testing and certification of the new residential solid biomass combustion 
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appliances. Additionally, the Panel recommended that the EPA consider different 

compliance time frames for different product categories to reduce the potential for 

logjams at test labs and the overall impact on companies that manufacture multiple 

categories. This proposal includes stepped emission limits for different categories and 

adds ISO-accredited laboratories and certifying bodies to increase the availability of 

laboratories and certifiers. Further, this proposal asks for specific comments on the 

schedules.

 The Panel recommended that the EPA continue to allow manufacturers to test a 

representative unit for a model line rather than testing and reporting results for each 

individual unit. This proposal continues to allow that.

 The Panel recommended that the EPA consider emphasizing that the NSPS will 

address only new units. This proposal does so.

 In the Panel Report, SBA and OMB recommended that the EPA not move forward 

with proposed emission limits for pellet stoves, indoor hydronic heaters, biomass 

pellet stoves, masonry heaters, masonry fireplace kits, site-built masonry fireplaces, 

coal stoves, cook stoves, bake ovens (including Native American Traditional Bake 

Ovens), camp stoves, outdoor fireplaces and chimineas. This proposal establishes 

emission limits for pellet stoves, which are at the same level as the proposed wood 

stove/heater standards and thus do not impose substantial compliance costs. The 

masonry heater industry asked for a standard and this proposal is responsive to that 

request. Indoor hydronic heaters are addressed because of the magnitude of their 

emissions and because their control is justified on BSER and cost-benefit grounds. 

The remainder of the appliances listed above are not included in this proposal.
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 In the panel report, SBA and OMB recommended that "where EPA estimates that the 

nationwide emissions are less than 300 tons per year (or some other value)... the EPA 

Administrator should consider options of not issuing an NSPS but rather consider 

allowing Regions and States to control such sources and consider other efforts, 

including voluntary standards to lower emissions.” EPA could not find a legal or 

policy justification for this arbitrary cutoff and it is not included in this proposal.

Further, the EPA does not agree with this recommendation, especially considering the 

strong recommendations by many states that the EPA regulate all residential wood 

heaters as soon as possible to provide another tool to help them with their efforts to 

reduce wood smoke emissions. As stated elsewhere in this proposal, the EPA is not 

proposing standards at this time for biomass pellet heater/stoves that are designed to 

only combust biomass other than wood, bake ovens, fireplaces, coal-only stoves, 

chimineas, ceremonial fires and commercial pizza ovens.

 Two panel members recommended that if the EPA decides to later pursue regulation 

of categories other than certified wood heaters, the EPA should convene another 

panel to address those categories at the appropriate time. The EPA does not agree 

with this recommendation for residential wood heaters because the EPA believes that 

the SERs already had multiple opportunities to address those categories. Furthermore, 

the EPA has conducted numerous meetings after the panel process was completed to 

provide much additional information (e.g., technical discussions of refined 

alternatives) and updates to stakeholders including the SERs and other small 

businesses and other interested parties. 
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As noted earlier, a copy of the panel final full report is included in the docket for 

this proposed rule. We invite comments on the report and on all aspects of the proposal 

and its impacts on small entities.

D. Unfunded Mandates Reform Act

This proposed rule contains no federal mandates under the provisions of Title II 

of the Unfunded Mandates Reform Act of 1995 (UMRA), 2 U.S.C. 1531-1538 that may

result in expenditures of $100 million or more for state, local or tribal governments, in 

the aggregate, or to the private sector in any 1 year. This proposed action imposes no 

enforceable duty on any state, local or tribal governments. The nationwide annualized 

average compliance cost of this proposed rule for directly affected appliances is $15.7

million/yr in the 2014-2022 timeframe (2010 dollars). Therefore, this proposed rule 

would not be subject to the requirements of sections 202 or 205 of the UMRA.

This proposed rule would also not be subject to the requirements of section 203 of 

UMRA because it contains no regulatory requirements that might significantly or 

uniquely affect small governments. The proposed rule would not apply to such 

governments and would impose no obligations upon them.

E. Executive Order 13132: Federalism

Executive Order 13132 (64 FR 43255, August 10, 1999) requires the EPA to 

develop an accountable process to ensure “meaningful and timely input by state and local 

officials in the development of regulatory policies that have federalism implications.” 

“Policies that have federalism implications” are defined in the Executive Order to include 

regulations that have “substantial direct effects on the states, on the relationship between 
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the national government and the states, or on the distribution of power and 

responsibilities among the various levels of government.”

This proposed rule does not have federalism implications. It would not have 

substantial direct effects on the states, on the relationship between the national 

government and the states, or on the distribution of power and responsibilities among the 

various levels of government, as specified in Executive Order 13132. The proposed rule 

would not impose any requirements on state and local governments. Thus, Executive 

Order 13132 does not apply to this proposed rule. Although section 6 of Executive Order 

13132 does not apply to this proposed action, the EPA did consult with representatives of 

state and local governments in developing this action. In the spirit of Executive Order 

13132 and consistent with the EPA policy to promote communications between the EPA 

and state and local governments, the EPA specifically solicits comment on this proposed 

rule from state and local officials. 

F. Executive Order 13175: Consultation and Coordination with Indian Tribal 

Governments

This proposed action does not have tribal implications, as specified in Executive 

Order 13175 (65 FR 67249, November 9, 2000). This proposed rule would not impose 

any requirements on tribal governments; thus, Executive Order 13175 does not apply to 

this action. Although Executive Order 13175 does not apply to this action, we recognize 

that the air quality and public health benefits to be achieved by this rule would benefit 

tribes, and we conducted outreach and consulted with representatives of tribal officials in 

developing this action. 
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During the development of this proposed rulemaking, the EPA conducted

outreach with numerous tribal representatives to provide opportunities for input prior to 

development of the proposed rule. We provided information at the July 2010, National 

Tribal Forum/National Tribal Air Association (NTAA) meeting in Albuquerque, New 

Mexico, and the November 2010, EPA Region 10 Tribal Leaders Summit in Juneau, 

Alaska. We also presented information on this proposed rulemaking in the April 2010,

issue of Tribal Air News and during the EPA/NTAA tribal workgroup conference calls 

(April 2010, July 2010, August 2010, and May 2013). Specifically, we received input 

from the EPA/NTAA tribal workgroup members on culturally relevant exclusions from 

the proposed standards. We agreed with their input, clarified that we do not intend to 

regulate ceremonial fires, and added a definition to the rule to exclude traditional Native 

American bake ovens.

On February 18, 2011, the EPA mailed letters to about 600 tribal leaders in the 

U.S. offering an opportunity for consultation on this proposal. We received requests from 

six tribes. These tribes agreed to discuss this proposal with us in a conference call held on 

March 22, 2011. The tribes were very supportive of this proposal and provided some 

helpful clarifications of definitions (e.g., Native American bake ovens) that we have 

incorporated in this proposal. 

We plan to continue to provide updates on the rule on the EPA/NTAA conference

calls and to offer opportunities to tribal leaders for consultation. The EPA specifically 

solicits additional comment on this proposed action from tribal officials.

G. Executive Order 13045: Protection of Children from Environmental Health 

Risks and Safety Risks
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Executive Order 13045, “Protection of Children from Environmental Health Risks 

and Safety Risks” (62 FR 19885, April 23, 1997), applies to any rule that: (1) is 

determined to be “economically significant,” as defined under Executive Order 12866;

and (2) concerns an environmental health or safety risk that the EPA has reason to 

believe may have a disproportionate effect on children. If the regulatory action meets 

both criteria, the EPA must evaluate the environmental health or safety effects of the 

planned rule on children and explain why the planned regulation is preferable to other 

potentially effective and reasonably feasible alternatives considered by the Agency. 

This proposed rule is not subject to Executive Order 13045 (62 FR 19885, April 

23, 1997) because the agency does not believe the environmental health risks or safety 

risks addressed by this action present a disproportionate risk to children. The report, 

“Analysis of Exposure to Residential Wood Combustion Emissions for Different SocioEconomic Groups,”

72 shows that on a nationwide basis, cancer risks due to residential 

wood smoke emissions among disadvantaged population groups generally are lower than 

the risks for the general population due to residential wood smoke emissions. One of the 

demographic variables examined for this report was that of children 18 years and 

younger. 

This proposed rule is expected to reduce environmental impacts for everyone, 

including children. This action proposes emissions limits at the levels based on BSER, as 

required by the CAA. Based on our analysis, we believe this rule would not have a 

 

72 “Analysis of Exposure to Residential Wood Combustion Emissions for Different 

Socio-Economic Groups, Revised Draft Report.” Prepared for Gil Wood, U.S. EPA, 

Office of Air Quality Planning and Standards, Research Triangle Park, NC. Prepared by 

EC/R Inc., EPA Contract No. EP-D-05-085, Work Assignment No. 4-3. April 22, 2010.
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disproportionate impact on children, and, in fact, will result in improvements to 

children’s health. 

The public is invited to submit comments or identify peer-reviewed studies and 

data that assess effects of early life exposure to smoke from residential wood heaters.

H. Executive Order 13211: Actions Concerning Regulations That Significantly 

Affect Energy Supply, Distribution, or Use

This proposed rule is not a “significant energy action” as defined in Executive 

Order 13211 (66 FR 28355, May 22, 2001), because it is not likely to have a significant 

adverse effect on the supply, distribution, or use of energy. Further, we have concluded 

that this rule is not likely to have any significant adverse energy effects. In general, we 

expect the NSPS to improve technology, including energy efficiency. By making use of 

wood fuel less polluting and more efficient, we might see an increase in the use of wood 

fuel, which would relieve pressure on traditional coal or petroleum based energy sources. 

However, as described in section IV.E, it is difficult to determine the precise energy

impacts that might result from this rule. This is because wood-fueled appliances compete 

with other biomass forms as well as more traditional oil, electricity and natural gas. We 

have not determined the potential conversion to other types of fuels and their associated 

appliances if the consumer costs of wood-fueled appliances increase and at what level 

that increase would drive consumer choice.

I. National Technology Transfer and Advancement Act

Section 12(d) of the National Technology Transfer and Advancement Act of 1995 

(“NTTAA”), Public Law No. 104-113 (15 U.S.C. 272 note) directs the EPA to use 

voluntary consensus standards (VCS) in its regulatory activities unless to do so would be 
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inconsistent with applicable law or otherwise impractical. VCS are technical standards 

(e.g., materials specifications, test methods, sampling procedures and business practices) 

that are developed or adopted by VCS bodies. The NTTAA directs the EPA to provide 

Congress, through OMB, explanations when the Agency decides not to use available and 

applicable voluntary consensus standards. 

This proposed rulemaking involves technical standards. The EPA proposes to use

several VCS test methods, in full or in part, including the following methods available for 

review at the ASTM website www.astm.org/epa: E2515-10 “Standard Test Method for 

Determination of Particulate Matter Emissions Collected by a Dilution Tunnel” (See also 

ASTM WK20442 proposed revision and ASTM WK31433 proposed revision); E2779-10 

“Standard Test Method for Determining Particulate Matter Emissions from Pellet 

Heaters;” E2780-10 “Standard Test Method for Determining Particulate Matter 

Emissions from Wood Heaters;” E2618-09 “Standard Test Method for Measurement of 

Particulate Matter Emissions and Heating Efficiency of Outdoor Solid Fuel-Fired 

Hydronic Heating Appliances” (See also ASTM WK26581 proposed revision); ASTM 

E2817-11 “Standard Test Method for Test Fueling Masonry Heaters;” ASTM WK26558 

“Specification for Calculation Method for Custom Designed, Site Built Masonry

Heaters.” Also, we propose to use, in part, the following test method available for review 

at the CSA website http://shop.csa.ca/en/canada/fuel-burning-equipment/b4151-

10/invt/27013322010/: CSA B415.1-10 “Performance Testing of Solid-fuel-burning 

Heating Appliances.” Finally, we propose to use, in part, the following test method 

prepared by the European Union: EN 303-5 “Heating boilers for solid fuels, hand and 

automatically stoked nominal heat output of up to 1025 MBtu –Terminology, 
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requirements, testing, and marketing.” We believe that all the methods listed above have 

some positive aspects that can help stakeholders determine emissions under various 

operation conditions. For more details on each method, please refer to the discussions in 

Section III of this preamble.

In addition, we determined that the VCS ASTM E871-82 (2006), “Standard Test 

Method for Moisture Analysis of Particulate Wood Fuels” is acceptable as an alternative 

to Methods 5H and 28.

The search identified five other VCS that were potentially applicable for this rule 

in lieu of the EPA reference methods. However, the EPA determined that the five 

candidate VCS would not be practical due to lack of equivalency, documentation, 

validation data and other important technical and policy considerations. The five VCS 

and other information and conclusion, including the search and review results, are in the 

docket for this proposed rule. The EPA welcomes comments on this aspect of the 

proposed rulemaking. Specifically, we invite the public to identify potentially applicable 

voluntary consensus standards and to explain why such standards, in whole or in part, 

should or should not be used in this regulation.

J. Executive Order 12898: Federal Actions to Address Environmental Justice in 

Minority Populations and Low-Income Populations

Executive Order 12898 (59 FR 7629, February 16, 1994) establishes federal 

executive policy on environmental justice. Its main provision directs federal agencies, to 

the greatest extent practicable and permitted by law, to make environmental justice part 

of their mission by identifying and addressing, as appropriate, disproportionately high 

and adverse human health or environmental effects of their programs, policies and 
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activities on minority populations and low-income populations in the U.S.

As discussed earlier, the report, “Analysis of Exposure to Residential Wood 

Combustion Emissions for Different Socio-Economic Groups,” shows that on a 

nationwide basis, cancer risks due to residential wood smoke emissions among 

disadvantaged population groups generally are lower than the risks for the general 

population due to residential wood smoke emissions. Thus, we have determined that this 

proposed rule would not have disproportionately high and adverse human health or 

environmental effects on minority, low-income or indigenous populations because it 

increases the level of environmental protection for all affected populations without 

having any disproportionately high and adverse human health or environmental effects on 

any population, including any minority low-income or indigenous population.

73 This 

proposed rule establishes national standards that would reduce primarily PM emissions 

from new residential wood heaters and, thus, would decrease the amount of these 

emissions to which all affected populations are exposed.

The EPA defines “Environmental Justice” to include meaning involvement of all 

people regardless of race, color, national origin or income with respect to the 

development, implementation and enforcement of environmental laws, regulations and 

polices.

 

73 “Analysis of Exposure to Residential Wood Combustion Emissions for Different 

Socio-Economic Groups, Revised Draft Report.” Prepared for Gil Wood, U.S. EPA, 

Office of Air Quality Planning and Standards, Research Triangle Park, NC. Prepared by

EC/R Inc., EPA Contract No. EP-D-05-085, Work Assignment No. 4-3. April 22, 2010.
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Page 162 of 342 - Standards of Performance for New Residential Wood Heaters, 

New Residential Hydronic Heaters and Forced-Air Furnaces, and New Residential 

Masonry Heaters

List of Subjects in 40 CFR Part 60

Environmental protection, Administrative practice and procedure, Air pollution control, 

Carbon monoxide, Hazardous substances, Intergovernmental relations, Particulate matter, 

Reporting and recordkeeping requirements.

Dated:

Bob Perciasepe,

Acting Administrator.
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For the reasons stated in the preamble, title 40, chapter I, of the Code of Federal 

Regulations is proposed to be amended as follows:

PART 60 – [AMENDED]

1. The authority citation for part 60 continues to read as follows:

Authority: 42 U.S.C. 7401-7671q.

Subpart A—[Amended]

2. Section 60.17 is amended by:

a. Adding paragraphs (a)(95) through (a)(101); and

b. Adding paragraph (p) to read as follows:

§60.17 Incorporations by reference.

* * * * *

(a) * * *

(95) ASTM E871-82 (2006), Standard Test Methods for Moisture Analysis of 

Particulate Wood Fuels, IBR approved for appendix A: Method 5H and Method 28.

(96) ASTM E2515-10, Standard Test Method for Determination of Particulate 

Matter Emissions Collected by a Dilution Tunnel, IBR approved for §60.534(c),

§60.5476(b) and §60.5488(b).

(97) ASTM E2779-10, Standard Test Method for Determining Particulate Matter 

Emissions from Pellet Heaters, IBR approved for §60.534(a)(2).

(98) ASTM E2618-09 Standard Test Method for Measurement of Particulate 

Matter Emissions and Heating Efficiency of Outdoor Solid Fuel-Fired Hydronic Heating 

Appliances, IBR approved for §60.5476(a)(2).
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(99) ASTM E2780-10, Standard Test Method for Determining Particulate Matter 

Emissions from Wood Heaters, IBR approved for §60.534(a)(2)

(100) ASTM E2817-11, Standard Test Method for Test Fueling Masonry Heaters, 

IBR approved for §60.5488(a).

(101) ASTM WK26558, New Specification for Calculation Method for Custom 

Designed, Site Built Masonry Heaters, IBR approved for §60.5488(c)(1). 

* * * * *

(p) This material is available for purchase from the Canadian Standards 

Association (CSA) at http://shop.csa.ca/en/canada/fuel-burning-equipment/b4151-

10/invt/27013322010/.

(1) CSA B415.1-10, Performance Testing of Solid-fuel-burning Heating 

Appliances, IBR approved for §60.534(d) and §60.5476(c) and (d).

(2) [Reserved]

3. Part 60 is amended by revising subpart AAA to read as follows:

Subpart AAA—Standards of Performance for New Residential Wood Heaters

Sec.

60.530 Am I subject to this subpart?

60.531 What definitions must I know?

60.532 What standards and associated requirements must I meet and by when?

60.533 What compliance and certification requirements must I meet and by when?

60.534 What test methods and procedures must I use to determine compliance with the 

standards and requirements for certification?
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60.535 What procedures must I use for laboratory accreditation or certifying body

accreditation?

60.536 What requirements must I meet for permanent labels and owner's manuals?

60.537 What records must I keep and what reports must I submit?

60.538 What activities are prohibited under this subpart?

60.539 What Petition for Review procedures apply to me?

60.539a Who implements and enforces this subpart?

60.539b What parts of the General Provisions do not apply?

Subpart AAA—Standards of Performance for New Residential Wood Heaters

§60.530 Am I subject to this subpart?

(a) You are subject to this subpart if you operate, manufacture, sell, offer for sale, 

import for sale, distribute, offer to distribute, introduce, or deliver for introduction, into 

commerce in the United States, an affected wood heater specified in paragraphs (a)(1) or 

(a)(2) of this section:

(1) Each adjustable burn rate wood heater with a current EPA certificate of 

compliance, single burn rate wood heaters with a current EPA certificate of compliance,

and each pellet stove with a current EPA certificate of compliance issued prior to 

[EFFECTIVE DATE OF FINAL RULE] according to the certification procedures in 

effect in this subpart at the time of certification that are manufactured on or after July 1, 

1988 are affected wood heaters.

(2) All other residential wood heaters under this subpart manufactured or sold on 

or after [EFFECTIVE DATE OF FINAL RULE] are affected wood heaters.
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(b) Each affected wood heater must comply with the provisions of this subpart

unless exempted under paragraphs (b)(1) through (b)(6) of this section.

(1) Affected wood heaters manufactured in the United States for export are 

exempt from the applicable emission limits of §60.532 and the requirements of §60.533.

(2) Affected wood heaters used for research and development purposes that are 

never offered for sale or sold and that are not used for the purpose of providing heat are 

exempt from the applicable emission limits of §60.532 and the requirements of §60.533. 

No more than 50 wood heaters manufactured per model line can be exempted for this 

purpose.

(3) Appliances that do not burn wood or wood pellets (such as coal-only heaters 

that meet the definition in §60.531 or corn-only pellet stoves) are exempt from the 

applicable emission limits of §60.532 and the requirements of §60.533. 

(4) Cookstoves that meet the definition in §60.531 are exempt from the applicable 

emission limits of §60.532 and the requirements of §60.533.

(5) Camp stoves that meet the definition in §60.531 are exempt from the 

applicable emission limits of §60.532 and the requirements of §60.533.

(6) Modification or reconstruction, as defined in §60.14 and §60.15 of Subpart A 

will not, by itself, make a wood heater an affected facility under this subpart.

(c) The following are not affected wood heaters and are not subject to this 

subpart:

(1) Residential hydronic heaters and residential forced-air furnaces subject to 

subpart QQQQ of this part.

(2) Residential masonry heaters subject to subpart RRRR of this part.
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(3) Appliances that are not residential heating devices (for example, manufactured 

or site-built masonry fireplaces).

(4) Traditional Native American bake ovens that meet the definition in §60.531.

§60.531 What definitions must I know?

As used in this subpart, all terms not defined herein have the meaning given them 

in the Clean Air Act and subpart A of this part.

Adjustable burn rate wood heater means an enclosed, wood-burning appliance 

capable of and intended for residential space heating or domestic water heating that is 

equipped with or installed with a damper or other mechanism to allow the operator to 

vary burn rate conditions, regardless of whether it is internal or external to the appliance. 

This definition does not distinguish between heaters that are free standing or fireplace 

inserts.

Accredited test laboratory means a test laboratory that is accredited for wood 

heater certification testing under §60.535 or is an independent third-party test laboratory

that is accredited by a nationally recognized accrediting entity under ISO-IEC Standard 

17025 to perform testing using the test methods specified in §60.534 and approved by the 

EPA for conducting testing under this subpart. 

At retail means the sale by a commercial owner of a wood heater to the ultimate 

purchaser.

Camp stove (sometimes also called cylinder stove or wall tent stove) means a 

portable stove equipped with a pipe or chimney exhaust capable of burning wood or coal 

intended for use in a tent or other temporary structure used for hunting, camping, fishing, 
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or other outdoor recreation. The primary purpose of the stove is to provide space heating, 

although cooking and heating water may be additional functions.

Catalytic combustor means a device coated with a noble metal used in a wood 

heater to lower the temperature required for combustion.

Certifying entity means an independent third party that is accredited by a 

nationally recognized accrediting entity under ISO-IEC Standard 17020 to perform 

certifications, inspections and audits under ISO-IEC Guide 17065 and approved by the 

EPA for conducting certifications, inspections and audits under this subpart. 

Coal-only heater means an enclosed, coal-burning appliance capable of space 

heating, or domestic water heating, which has all of the following characteristics:

(1) An opening for emptying ash that is located near the bottom or the side of the 

appliance;

(2) A system that admits air primarily up and through the fuel bed;

(3) A grate or other similar device for shaking or disturbing the fuel bed or powerdriven mechanical stoker;

(4) Installation instructions that state that the use of wood in the stove, except for 

coal ignition purposes, is prohibited by law; and

(5) The model is listed by a nationally recognized safety-testing laboratory for use 

of coal only, except for coal ignition purposes.

Commercial owner means any person who owns or controls a wood heater in the 

course of the business of the manufacture, importation, distribution (including shipping 

and storage), or sale of the wood heater.
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Cookstove means a wood-fired appliance that is designed primarily for cooking 

food and that has the following characteristics:

(1) An oven, with volume of 0.028 cubic meters (1 cubic foot) or greater, and an 

oven rack;

(2) A device for measuring oven temperatures;

(3) A flame path that is routed around the oven;

(4) An ash pan;

(5) An ash clean-out door below the oven;

(6) The absence of a fan or heat channels to dissipate heat from the appliance;

(7) A cooking surface measured in square inches or square feet that is 1.5 times 

greater than the firebox, which is measured in cubic inches or cubic feet. Example: A 

firebox of 2 cubic feet would have a cooking surface of at least 3 square feet;

(8) A portion of at least four sides of the oven is exposed to the flame path during 

the heating cycle of the oven. A flue gas bypass may exist for temperature control.

Manufactured means completed and ready for shipment (whether or not 

packaged).

Manufacturer means any person who constructs or imports into the United States 

a wood heater.

Model line means all wood heaters offered for sale by a single manufacturer that 

are similar in all material respects. 

Particulate matter (PM) means total particulate matter including coarse PM 

(PM10) and fine PM (PM2.5).
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Pellet stove means an enclosed, solid fuel burning device capable of and intended 

for residential space heating or domestic water heating that is designed specifically to 

burn wood pellet fuel that incorporates induced air flow, is installed with an automatic 

pellet feeder, and is a free standing room heater or fireplace insert.

Representative affected wood heater means an individual wood heater that is 

similar in all material respects to other wood heaters within the model line it represents.

Room heater means an enclosed, wood-burning appliance capable of and intended 

for residential space heating. Unless otherwise specified, these devices include adjustable 

burn rate wood heaters, single burn rate wood heaters and pellet stoves.

Sale means the transfer of ownership or control, except that a transfer of control 

of an affected wood heater for research and development purposes within the scope of 

§60.530(b)(2) is not a sale.

Seasoned wood means wood with a moisture content of 20 percent or less.

Similar in all material respects means that the construction materials, exhaust and 

inlet air system, and other design features are within the allowed tolerances for 

components identified in §60.533(k).

Single burn rate wood heater means an enclosed, wood-burning appliance 

capable of and intended for residential space heating or domestic water heating that is not 

equipped with or installed with a damper to allow the operator to vary burn rate 

conditions.

Traditional Native American bake oven means a wood or other solid fuel burning 

appliance that is designed primarily for use by Native Americans for food preparation, 

cooking, warming, or for instructional, recreational, cultural or ceremonial purposes.
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Valid certification test means a test that meets the following criteria:

(1) The Administrator was notified about the test in accordance with §60.534(f); 

(2) The test was conducted by an accredited test laboratory;

(3) The test was conducted on a wood heater similar in all material respects to 

other wood heaters of the model line that is to be certified; and

(4) The test was conducted in accordance with the test methods and procedures 

specified in §60.534.

Wood heater means an enclosed, wood burning-appliance capable of and intended 

for residential space heating or domestic water heating. Unless otherwise specified, these 

devices include adjustable burn rate wood heaters, single burn rate wood heaters and 

pellet stoves.

Wood pellet fuel means refined and densified wood shaped into small pellets or 

briquettes that are uniform in size, shape, moisture, density and energy content. 

§60.532 What standards and associated requirements must I meet and by when?

(a) 1990 Particulate Matter Standards. Unless exempted under §60.530, each 

adjustable burn rate wood heater and pellet stove with a current EPA certification issued 

prior to [EFFECTIVE DATE OF FINAL RULE], according to the certification 

procedures in effect in this subpart at the time of certification, must comply with the 

following particulate matter emission limits as determined by the applicable test methods 

and procedures in §60.534(a) through (c) until the current certification expires as 

specified in §60.533(h)(1), or it is revoked by the Administrator as specified in 

§60.533(l), whichever is first. After the certificate expires or is revoked, individual wood 
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heaters in that model line can no longer be manufactured or sold unless the manufacturer 

receives a new certificate of compliance from the Administrator.

(1) An affected wood heater equipped with a catalytic combustor must not 

discharge into the atmosphere any gases that contain particulate matter in excess of a 

weighted average of 4.1 g/hr (0.009 lb/hr) as specified in the applicable test method. 

Particulate matter emissions during any test run at any burn rate that is required to be 

used in the weighted average as specified in the applicable test method must not exceed 

the value calculated for “C” (rounded to 2 significant figures) calculated using the 

following equation:

(i) At burn rates less than or equal to 2.82 kg/hr (6.2 lb/hr), 

Where:

BR = Burn rate in kg/hr (lb/hr)

C = Actual particulate matter emission rate in g/hr (lb/hr) per burn rate in a given test run 

K1= 3.55 g/kg (0.00355 lb/lb)

K2= 4.98 g/hr (0.0.011 lb/hr)

(ii) At burn rates greater than 2.82 kg/hr (6.2 lb/hr), C = 15 g/hr (0.033 lb/hr).

(2) An affected wood heater not equipped with a catalytic combustor must not 

discharge into the atmosphere any gases that contain particulate matter in excess of a 

weighted average of 7.5 g/hr (0.017 lb/hr) as specified in the applicable test method. 

Particulate matter emissions must not exceed 15 g/hr (0.033 lb/hr) during any test run at a 

burn rate less than or equal to 1.5 kg/hr (3.3 lb/hr) that is required to be used in the 

weighted average as specified in the applicable test method and particulate matter 
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emissions must not exceed 18 g/hr (0.040 lb/hr) during any test run at a burn rate greater 

than 1.5 kg/hr (3.3 lb/hr) that is required to be used in the weighted average as specified 

in the applicable test method.

(3) As an alternative, an affected wood heater subject to paragraph (a) of this 

section may elect to comply with the requirements in paragraph (b) of this section.

(b) 2014 Particulate Matter Standards. Unless exempted under §60.530 or subject 

to the standards specified in paragraph (a) of this section, each adjustable burn rate wood 

heater or pellet stove manufactured on or after [EFFECTIVE DATE OF FINAL 

RULE] or sold at retail for use in the United States on or after [6 MONTHS AFTER 

EFFECTIVE DATE OF FINAL RULE] must comply with the emission limits 

specified in paragraphs (b)(1) or (b)(2) of this section, as applicable. Unless exempted 

under §60.530, each single burn rate wood heater manufactured on or after 

[EFFECTIVE DATE OF FINAL RULE] or sold at retail on or after [6 MONTHS 

AFTER EFFECTIVE DATE OF FINAL RULE] must comply with the emission limit 

specified in paragraph (b)(3) of this section. Compliance for all sources must be 

determined by the test methods and procedures in §60.534.

(1) An adjustable burn rate wood heater or pellet stove that is an affected wood 

heater equipped with a catalytic combustor must not discharge into the atmosphere any

gases that contain particulate matter in excess of a weighted average of 4.5 g/hr (0.01

lb/hr). 

(2) An adjustable burn rate wood heater or pellet stove that is an affected wood 

heater not equipped with a catalytic combustor and capable of making burn rate 
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adjustments must not discharge into the atmosphere any gases that contain particulate 

matter in excess of a weighted average of 4.5 g/hr (0.01 lb/hr). 

(3) A single burn rate wood heater that is an affected wood heater must not 

discharge into the atmosphere any gases that contain particulate matter in excess of 4.5

g/hr (0.01 lb/hr). 

(c) 2019 Particulate Matter Standards. Unless exempted under §60.530 or subject 

to the standards specified in paragraph (a) of this section, each adjustable burn rate wood 

heater, pellet stove or single burn rate wood heater manufactured or sold at retail for use 

in the United States on or after [5 YEARS AFTER EFFECTIVE DATE OF FINAL 

RULE] must not discharge into the atmosphere any gases that contain particulate matter 

in excess of 1.3 g/hr (0.003 lb/hr) for any burn rate. Compliance for all sources must be 

determined by the test methods and procedures in §60.534.

(d) [Reserved]

(e) Pellet Fuel Requirements. Operators of wood heaters that are certified to burn 

pellet fuels may only burn pellets that have been produced under a licensing agreement 

with the Pellet Fuels Institute or an equivalent organization approved by the EPA. The 

pellet fuel must meet the following minimum requirements:

(1) Density: consistent hardness and energy content with a minimum density of 38 

pounds/cubic foot; 

(2) Dimensions: maximum length of 1.5 inches and diameter between 0.230 and 

0.285 inches; 

(3) Inorganic fines: less than or equal to 1 percent;

(4) Chlorides: less than or equal to 300 parts per million by weight; 
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(5) Ash content: no more than 2 percent; and

(6) A quality assurance process licensed by the Pellet Fuels Institute or equivalent

organization approved by EPA.

(f) Prohibited Fuel Types. No person is permitted to burn any of the following 

materials in an affected wood heater:

(1) Residential or commercial garbage;

(2) Lawn clippings or yard waste;

(3) Materials containing rubber, including tires;

(4) Materials containing plastic;

(5) Waste petroleum products, paints or paint thinners, or asphalt products;

(6) Materials containing asbestos;

(7) Construction or demolition debris;

(8) Paper products, cardboard, plywood, or particleboard. The prohibition against 

burning these materials does not prohibit the use of fire starters made from paper, 

cardboard, saw dust, wax and similar substances for the purpose of starting a fire in an 

affected wood heater; 

(9) Railroad ties or pressure treated wood;

(10) Manure or animal remains; or

(11) Salt water driftwood or other previously salt water saturated materials.

(g) Owner’s Manual. A person must not operate an affected residential wood 

heater in a manner inconsistent with the owner’s manual. The owner’s manual must 

clearly specify that operation in a manner inconsistent with the owner’s manual would 

violate the warranty.
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(h) Temperature Sensor Requirement. An affected wood heater equipped with a 

catalytic combustor must be equipped with a temperature sensor that can monitor 

combustor gas stream temperatures within or immediately downstream [within 2.54 

centimeters (1 inch)] of the catalytic combustor surface.

§60.533 What compliance and certification requirements must I meet and by when?

(a) Certification Requirement. Each affected wood heater must be certified to be 

in compliance with the applicable emission standards and other requirements of this 

subpart. For each model line manufactured or sold by a single entity, e.g., company or 

manufacturer, compliance with applicable emission standards of §60.532 may be 

determined based on testing of representative affected wood heaters within the model 

line. If one entity, licenses a model line to another entity, each entity’s model line must 

be certified. If an entity changes the name of the entity or the name of the model, the 

manufacturer must apply for a new certification.

(1) Prior to [EFFECTIVE DATE OF FINAL RULE], the manufacturer must

submit to the EPA the information required in paragraph (b) of this section and follow 

either the certification process in paragraphs (b) through (e) of this section or the 

certifying entity based application process specified in paragraph (f) of this section. 

(2) On or after [EFFECTIVE DATE OF FINAL RULE], the manufacturer must 

submit the information required in paragraph (b) of this section and follow the certifying 

entity based application process specified in paragraph (f) of this section.

(b) Application for Certificate of Compliance. Any manufacturer of an affected 

wood heater must apply to the Administrator for a certificate of compliance for each 

model line. The application must be submitted to: XXXX Compliance Program at 
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xxxx.gov/yyyy. The application must be signed by a responsible representative of the 

manufacturer or an authorized representative and must contain the following:

(1) The model name and/or design number and responsible contact information 

for the manufacturer and all authorized representatives, including name, affiliation, 

physical address, telephone number, and email address.

(2) Engineering drawings and specifications of components that may affect 

emissions (including specifications for each component listed in paragraph (k) of this 

section). Manufacturers may use complete assembly or design drawings that have been 

prepared for other purposes, but must designate on the drawings the dimensions of each 

component listed in paragraph (k) of this section. Manufacturers must identify tolerances 

of components of the tested unit listed in paragraph (k)(2) of this section that are different 

from those specified in that paragraph, and show that such tolerances may not reasonably 

be anticipated to cause wood heaters in the model line to exceed the applicable emission 

limits. The drawings must identify how the emission critical parts, such as air tubes and 

catalyst, can be readily inspected and replaced. The drawings may be submitted either in 

hard copy or electronic format.

(3) A statement whether the firebox or any firebox component (including the 

materials listed in paragraph (k)(3) of this section) will be composed of material different 

from the material used for the firebox or firebox component in the wood heater on which 

certification testing was performed and a description of any such differences.

(4) Clear identification of any confidential business information. Submit such 

information under separate cover to the EPA CBI Office; Attn: Residential Wood Heater 

Compliance Program. Note that emissions data, including information necessary to 
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determine emission rates in the format of the standard, cannot be claimed as confidential 

business information.

(5) All documentation pertaining to a valid certification test, including the 

complete test report and, for all test runs: raw data sheets, laboratory technician notes, 

calculations, and test results. Documentation must include the items specified in the 

applicable test methods. The test report must include a summary table that clearly 

presents the individual and overall emission rates, efficiencies, and heat output range. 

Submit the test report and all associated required information according to the procedures 

for electronic reporting specified in §60.537(f).

(6) A copy of the warranties for the model line, including a statement that the 

warranties are void if the unit is used to burn materials for which the unit is not certified

by the EPA.

(7) A statement that the manufacturer or certifying entity will conduct a quality

assurance program for the model line that satisfies the requirements of paragraph (m) of 

this section.

(8) A statement describing how the tested unit was sealed by the laboratory after 

the completion of certification testing and that such unit will be stored by the 

manufacturer in the sealed state until 1 year after the certification expires.

(9) Statements that the wood heaters manufactured under this certificate will be—

(i) Similar in all material respects as defined in this subpart to the wood heater 

submitted for certification testing, and

(ii) Labeled as prescribed in §60.536.
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(iii) Accompanied by an owner’s manual that meets the requirements in §60.536. 

In addition, a copy of the owner’s manual must be submitted to the EPA and be available 

on the manufacturer’s website.

(9) A statement that the manufacturer has entered into a contract with an 

accredited laboratory that satisfies the requirements of paragraph (e) of this section.

(10) A statement that the accredited certifying body is allowed to submit 

information on behalf of the manufacturer. 

(c)(1) Administrator Approval Process. The Administrator will electronically

issue a certificate of compliance for a model line if the Administrator determines, based 

on all information submitted by the applicant and any other relevant information 

available, that:

(i) A valid certification test demonstrates that the representative affected wood 

heater complies with the applicable emission standards in §60.532,

(ii) Any tolerances for components listed in paragraph (k)(2) of this section that 

are different from those specified in those paragraphs may not reasonably be anticipated 

to cause wood heaters in the model line to exceed the applicable emission limits; and

(iii) The requirements of paragraph (b) of this section have been met. 

(2) The Administrator will deny certification if the Administrator determines that 

the criteria in paragraph (c)(1) of this section have not been satisfied. Upon denying 

certification under this paragraph, the Administrator will give written notice to the 

manufacturer setting forth the basis for this determination.
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(d) Prior to [EFFECTIVE DATE OF THE FINAL RULE], the Administrator 

will issue the certificate for the most stringent particulate matter emission standard that 

the unit meets under §60.532(a) or (b), as applicable.

(e) To receive EPA certification, a manufacturer must enter into a contract with 

the accredited laboratory that performed the certification test, under which the laboratory

will:

(1) Conduct the compliance audit test at no additional cost to the manufacturer if 

the EPA selects that laboratory to conduct the test; or

(2) Pay the manufacturer the cost of a compliance audit test (as determined by the 

EPA) if the EPA selects any other laboratory to conduct the test.

(f) Certifying Entity-Based Application Process. 

(1) Any manufacturer of an affected wood heater must apply to the Administrator 

for a certificate of compliance for each model line. The manufacturer must meet the 

following requirements: 

(i) The manufacturer must contract with a certifying entity for certification 

services.

(ii) The manufacturer must submit the materials specified in paragraph (b) of this 

section and a quality control plan that meets the requirements of paragraph (m)(4) of this 

section to the certifying entity. The quality control plan must ensure that units within a 

model line accurately reflect emission-critical components of the model line design, and 

it must include design drawings for the model line.

(iii) The manufacturer must apply to the certifying entity for a certification of 

conformity with the applicable requirements of this subpart for the model line.
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(A) After testing by an accredited test laboratory is complete, certification of 

conformity with the emission standards in §60.532 must be performed by the 

manufacturer’s contracted certifying entity. 

(B) The certifying entity can certify conformity if the emission tests have been 

conducted per the appropriate guidelines and the test report is complete and accurate and 

the instrumentation is properly calibrated and the test report shows that the representative 

affected wood heater meets the applicable emission limits specified in §60.532 and the 

quality control plan is adequate to ensure that units within the model line will be similar 

in all material respects to the wood heater submitted for certification testing. 

(iv) The manufacturer must then request that the certifying entity electronically

submit, on behalf of the manufacturer, an application for EPA certification that includes 

the certification of conformity, quality control plan, test report and supporting 

documentation. 

(v) The submission must include a statement signed by a responsible official of 

the manufacturer that the manufacturer has complied with all requirements of this subpart 

and that the manufacturer remains responsible for compliance regardless of any error by

the certifying entity.

(2) The Administrator will electronically issue to the manufacturer a certificate of 

compliance for a model line if it is determined, based on all of the information submitted 

in the application for certification and any other relevant information, that:

(i) A valid certification of conformity has demonstrated that the representative 

affected wood heater complies with the applicable emission standards in §60.532; and
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(ii) Any tolerances or materials for components listed in paragraph (k)(2) or (3) of 

this section that are different from those specified in those paragraphs may not be 

reasonably anticipated to cause wood heaters in the model line to exceed the applicable 

emission limits.

(iii) The requirements of paragraphs (b) of this section have been met. 

(iv) A valid certificate of conformity for the model line has been prepared and 

submitted.

(3) The Administrator will deny certification if the Administrator determines that 

the criteria in paragraph (f)(2) of this section have not been satisfied. Upon denying 

certification under this paragraph, the Administrator will give written notice to the 

manufacturer setting forth the basis for the determination. 

(g) Waiver from Submitting Test Results. An applicant for certification may apply

for a potential waiver of the requirement to submit the results of a certification test 

pursuant to paragraph (b)(3) of this section, if the wood heater meets either of the 

following conditions:

(1) The wood heaters of the model line are similar in all material respects, as 

defined in this subpart, to another model line that has already been issued a certificate of 

compliance. A manufacturer that seeks a waiver of certification testing must identify the 

model line that has been certified, and must submit a copy of an agreement with the 

owner of the design permitting the applicant to produce wood heaters of that design.

(2) The manufacturer has previously conducted a valid certification test to

demonstrate that the wood heaters of the model line meet the applicable standard 

specified in §60.532(a), and that test also demonstrates that the wood heaters of the 
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model line meet the applicable standard specified in §60.532(b). This option is only

potentially available a maximum of one time per model line. 

(h) Certification Period. Unless revoked sooner by the Administrator, a certificate 

of compliance will be valid for the following periods as applicable:

(1) For a model line certified as meeting the emission standards in §60.532(a), a 

certificate of compliance will be valid for 5 years from the date of issuance.

(2) For a model line certified as meeting emission standards in §60.532(b), a 

certificate of compliance will be valid for 5 years from the date of issuance.

(3) For a model line certified as meeting emission standards in §60.532(c), a 

certificate of compliance will be valid for 5 years from the date of issuance.

(i) Renewal of Certification.

(1) The certificate must be recertified or renewed every 5 years or the 

manufacture may choose to no longer manufacture or sell that model. If the manufacturer 

chooses to no longer manufacture or sell that model, then the manufacturer must submit a 

statement to EPA for that model. A manufacturer of an affected wood heater may apply 

to the Administrator for potential renewal of their certificate by submitting the material 

specified in §60.533(b) and following the procedures specified in §60.533(f) or by 

affirming in writing that the wood heater has been subject to no changes that would 

impact emissions and requesting a potential waiver from certification testing. 

(2) If the Administrator grants a renewal of certification, the Administrator will 

give written notice to the manufacturer setting forth the basis for the determination and 

issue a certification renewal.
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(3) If the Administrator denies the request for a renewal of certification, the 

Administrator will give written notice to the manufacturer setting forth the basis for the 

determination.

(j) [Reserved]

(k) Recertification.

(1) The manufacturer must recertify a model line whenever any change is made in 

the design submitted pursuant to paragraph (b)(2) of this section that is presumed to 

affect the particulate matter emission rate for that model line. The Administrator may

potentially waive this requirement upon written request by the manufacturer, if it is

determined that the change may not reasonably be anticipated to cause wood heaters in 

the model line to exceed the applicable emission limits. The granting of such a waiver 

does not relieve the manufacturer of any compliance obligations under this subpart.

(2) Any change in the design tolerances of any of the following components 

(where such components are applicable) is presumed to affect particulate matter and 

carbon monoxide emissions and efficiency if that change exceeds ±0.64 cm (±1/4 inch) 

for any linear dimension and ±5 percent for any cross-sectional area relating to air 

introduction systems and catalyst bypass gaps unless other dimensions and crosssectional areas are previously approved by the Administrator under paragraph (c)(1)(ii) of 

this section:

(i) Firebox: Dimensions;

(ii) Air introduction systems: Cross-sectional area of restrictive air inlets and 

outlets, location and method of control;

(iii) Baffles: Dimensions and locations;
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(iv) Refractory/insulation: Dimensions and location;

(v) Catalyst: Dimensions and location;

(vi) Catalyst bypass mechanism and catalyst bypass gap tolerances (when bypass 

mechanism is in closed position): Dimensions, cross-sectional area, and location;

(vii) Flue gas exit: Dimensions and location;

(viii) Door and catalyst bypass gaskets: Dimensions and fit;

(ix) Outer shielding and coverings: Dimensions and location;

(x) Fuel feed system: For wood heaters that are designed primarily to burn wood 

pellets and other wood heaters equipped with a fuel feed system, the fuel feed rate, auger 

motor design and power rating, and the angle of the auger to the firebox; and

(xi) Forced air combustion system: For wood heaters so equipped, the location 

and horsepower of blower motors and the fan blade size.

(3) Any change in the materials used for the following components is presumed to 

affect particulate matter emissions and efficiency:

(i) Refractory/insulation; or

(ii) Door and catalyst bypass gaskets.

(4) A change in the make, model, or composition of a catalyst is presumed to 

affect particulate matter and carbon monoxide emissions and efficiency, unless the 

change has been approved in advance by the Administrator, based on test data in the 

same model stove that demonstrate that the replacement catalyst is equivalent to or better 

than the original catalyst in terms of particulate matter emission reduction.

(l) Criteria for Revocation of Certification.
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(1) The Administrator may revoke certification if it is determined that the wood 

heaters being manufactured or sold in that model line do not comply with the 

requirements of this subpart. Such a determination will be based on all available 

evidence, including but not limited to:

(i) Test data from a retesting of the original unit on which the certification test 

was conducted or a similar unit;

(ii) A finding that the certification test was not valid. (iii) A finding that the 

labeling of the wood heater model line or the owner’s manual or marketing information 

does not comply with the requirements of §60.536;

(iii) Failure by the manufacturer to comply with reporting and recordkeeping 

requirements under §60.537;

(iv) Physical examination showing that a significant percentage (as defined in the 

quality assurance plan, but no larger than 1 percent) of production units inspected is not 

similar in all material respects to the representative affected wood heater submitted for 

testing; or

(v) Failure of the manufacturer to conduct a quality assurance program in 

conformity with paragraph (m) of this section.

(2) Revocation of certification under this paragraph will not take effect until the 

manufacturer concerned has been given written notice by the Administrator setting forth 

the basis for the proposed determination and an opportunity to request a review under 

§60.539.

(m) Quality Assurance Program.
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(1) On or after [EFFECTIVE DATE OF FINAL RULE], for each certified 

model line, the manufacturer must conduct a quality assurance program that satisfies the 

requirements of this section The quality assurance program requirements of this section 

supersede the quality assurance plan requirements specified in §60.533(o) of the 1988 

rule. By [DATE 60 DAYS AFTER EFFECTIVE DATE OF FINAL RULE], for 

model lines that had a valid EPA certification on [DATE 60 DAYS AFTER 

EFFECTIVE DATE OF FINAL RULE], manufacturers must submit the quality

assurance plan to the EPA Administrator for review and approval. 

(i) The manufacturer must prepare and operate according to a quality assurance 

plan for each certified model line that has specific inspection and testing requirements for 

ensuring that units within a model line accurately reflect emission-critical components of 

the model line design and meet the emissions standards in §60.532.

(ii) The quality assurance plan must be approved within 30 days by the certifying 

entity as part of the certification of conformity process specified in paragraph (f) of this 

section. 

(iii) Within 30 days after approval by the certifying entity, the quality control plan 

must also be submitted to EPA for review and approval.

(iv) The certifying entity must conduct quarterly unannounced audits under ISOIEC Guide 17065 and ISO-EC Standard 17020 to ensure that the manufacturer’s quality

control plan is being implemented. 

(v) The certifying entity must prepare a report for each audit under ISO-IEC 

Guide 17065 and ISO-EC Standard 17020 that fully documents the results of the audit, 

and the manufacturer must include in their contract with the certifying entity the 
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authorization and requirement to submit all such reports to the EPA within 30 days. In the 

audit report, the certifying entity must identify deviations from the manufacturer’s quality 

control plan and specify the corrective actions that need to be taken to address each 

identified deficiency. 

(vi) The manufacturer must report within 30 days to the certifying entity and to 

the EPA its responses to any deficiencies identified in an audit report. 

(n) EPA Compliance Audit Testing.

(1)(i) The Administrator may select by written notice wood heaters for 

compliance audit testing to determine compliance with the emission standards in 

§60.532. 

(ii) The written notification shall be forwarded to the manufacturer by the 

Administrator and shall include the name and address of the laboratory selected to 

perform the audit test and the model name and serial number of the wood heater(s) 

selected to undergo audit testing.

(2)(i) The Administrator may test, or direct the manufacturer to have tested, the 

wood heater(s) selected under paragraph (n)(1)(i) of this section in a laboratory

accredited under §60.535 that is selected pursuant to paragraph (n)(3) of this section.

(ii) The expense of the compliance audit test is the responsibility of the wood 

heater manufacturer. A manufacturer may require the laboratory that performed the 

certification test to bear the expense of an audit test by means of the contract required 

under paragraph (e) of this section. The manufacturer will bear the cost of audit testing if 

the laboratory with which the manufacturer had a contract has ceased business or is 

otherwise legally unable to honor the contract. The manufacturer will also bear the cost 
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of audit testing if the manufacturer has not entered into contract with an accredited test 

laboratory to perform audit testing.

(iii) The test must be conducted using the same test method and procedure used to 

obtain certification or a new test method approved by the EPA Administrator. If the 

certification test consisted of more than one particulate matter sampling test method, the 

Administrator may direct the test laboratory as to which of these methods to use for the 

purpose of audit testing. The Administrator will notify the manufacturer at least 1 week 

prior to any test under this paragraph, and allow the manufacturer and/or his authorized 

representatives to observe the test.

(3) The Administrator may select any accredited test laboratory or federal 

laboratory for audit testing.

(4) Revocation of Certification.

(i) If emissions from a wood heater tested under paragraph (n)(2) of this section 

exceed the certification emission values limit by more than 50 percent, the Administrator 

will notify the manufacturer that certification for that model line is suspended effective 

72 hours from the receipt of the notice, unless the suspension notice is withdrawn by the 

Administrator. The suspension will remain in effect until withdrawn by the 

Administrator, or 30 days from its effective date (if a revocation notice under paragraph 

(n)(5)(ii) of this section is not issued within that period), or the date of final agency action 

on revocation, whichever occurs earlier.

(ii)(A) If emissions from a wood heater tested under paragraph (n)(2) of this 

section exceed the applicable emission limit, the Administrator will notify the 

manufacturer that certification is revoked for that model line.
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(B) A suspension under paragraph (n)(4)(i) or a revocation notice under paragraph 

(n)(4)(ii)(A) of this section will become final and effective 60 days after receipt by the 

manufacturer, unless it is withdrawn, a supplemental review is requested under §60.539, 

or the deadline for requesting a supplemental review is extended.

(C) The Administrator may extend the deadline for requesting a supplemental 

review for up to 60 days for good cause.

(D) A manufacturer may extend the deadline for requesting a supplemental 

review for up to 6 months, by agreeing to a voluntary suspension of certification.

(iii) Any notification under paragraph (n)(4)(i) or (n)(4)(ii) of this section will 

include a copy of a preliminary test report from the accredited test laboratory or federal 

test laboratory. The test laboratory must provide a preliminary test report to the 

Administrator within 10 days of the completion of testing, if a wood heater exceeds the 

applicable emission limit in §60.532. The test laboratory must provide the Administrator 

and the manufacturer, within 30 days of the completion of testing, all documentation 

pertaining to the test, including the complete test report and raw data sheets, laboratory

technician notes, and test results for all test runs.

(iv) Upon receiving notification of a test failure under paragraph (n)(4)(ii) of this 

section, the manufacturer may request up to four additional wood heaters from the same 

model line be selected under paragraph (n)(1) of this section for testing at the 

manufacturer’s expense, at the test laboratory that performed the emissions test for the 

Administrator.

(v) Whether or not the manufacturer proceeds under paragraph (n)(4)(iv) of this 

section, the manufacturer may submit any relevant information to the Administrator, 
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including any other test data generated pursuant to this subpart. The manufacturer must 

pay the expense of any additional testing.

(vi) The Administrator will withdraw any notice issued under paragraph (n)(4)(ii) 

of this section if tests under paragraph (n)(4)(iv) of this section show either—

(A) That all wood heaters tested for the manufacturer met the applicable emission 

limits; or

(B) That the second and third wood heaters selected met the applicable emission 

limits and the average of all three (including the original audit test) was below the 

applicable emission limits.

(C) The Administrator will revise the certification values based on the test data 

and other relevant information and the manufacturer must revise the labels and marketing 

information accordingly.

(vii) The Administrator may withdraw any proposed revocation, if the 

Administrator finds that an audit test failure has been rebutted by information submitted 

by the manufacturer under paragraph (n)(4)(iv) of this section and/or (n)(4)(v) of this 

section or by any other relevant information available to the Administrator.

§60.534 What test methods and procedures must I use to determine compliance with the 

standards and requirements for certification?

Test methods and procedures specified in this section or in appendices of this part, 

except as provided under §60.8(b), must be used to determine compliance with the 

standards and requirements for certification under §§60.532 and 60.533 as follows:
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(a)(1) Method 28 of appendix A-8 of this part must be used to establish the 

certification test conditions and the particulate matter emission values for affected wood 

heaters subject to the 1990 particulate matter standards specified in §60.532(a).

(2) For affected wood heaters subject to the 2014 particulate matter standards 

specified in §60.532(b), you must conduct testing according to paragraphs

§60.534(a)(2)(i) and (ii) of this section and submit the full test reports. You have the 

option of submitting the test results of either (a)(2)(i) or (ii) of this section to the 

Administrator as specified under §60.537 for certification compliance.

(i) Conduct testing with crib wood using EPA Method 28R of appendix A-8 of 

this part to establish the certification test conditions and the particulate matter emission 

values.

(ii) Conduct testing with cord wood using EPA Method 28R of appendix A-8 of 

this part to establish the certification test conditions and the particulate matter emission 

values.

(3) For affected wood heaters subject to the 2019 particulate matter standards 

specified in §60.532(c), you must conduct testing with cord wood using EPA Method 

28R of appendix A-8 of this part to establish the certification test conditions, except that 

you should first test Burn Rate Categories 1 and 4 and then test 2 more times for 

whichever burn rate category is worse and then report the results separately per burn rate 

category.

(b) For affected wood heaters subject to the 1990 particulate matter standards 

specified in §60.532(a), emission concentrations must be measured with Method 5G of 
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appendix A-3 of this part, i.e., using a dilution tunnel sampling location. Method 5H is no 

longer allowed for certification testing.

(c) For affected wood heaters subject to the 2014 and 2019 particulate matter 

standards specified in §60.532(b) and (c), emission concentrations must be measured 

with ASTM E2515-10.

(d) Canadian Standards Administration Method B415.1-10, section 13.7, must be 

used to measure the efficiency and carbon monoxide output of the tested appliance.

(e) [Reserved]

(f) The manufacturer of an affected wood heater must notify the Administrator of 

the date that certification testing is scheduled to begin by email to XXXX Compliance 

Program at xxx.gov/yyyy. This notice must be received by the EPA at least 30 days 

before the start of testing. The notification of testing must include the manufacturer's 

name and physical and email addresses, the accredited test laboratory's name and 

physical and email addresses, certifying entity name, the model name and number (or, if 

unavailable, some other way to distinguish between models), and the dates of testing.

(g) The accredited test laboratory must allow the manufacturer, the EPA and 

delegated states to observe certification testing. However, manufacturers must not 

involve themselves in the conduct of the test after the pretest burn has begun. 

Communications between the manufacturer and laboratory or certifying entity personnel 

regarding operation of the wood heater must be limited to written communications 

transmitted prior to the first pretest burn of the certification series. Written 

communications between the manufacturer and laboratory personnel may be exchanged 

during the certification test only if deviations from the test procedures are observed that 
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constitute improper conduct of the test. All communications must be included in the test 

documentation required to be submitted pursuant to §60.533(b)(3) and must be consistent 

with instructions provided in the owner's manual required under §60.536(f), except to the 

extent that they address details of the certification tests that would not be relevant to 

owners or regulators.

§60.535 What procedures must I use for laboratory accreditation or certifying body 

accreditation?

(a)(1) A laboratory must apply to the Administrator for accreditation as an EPA 

accredited test laboratory by submitting documentation that the laboratory is accredited 

by a nationally recognized accrediting entity under ISO-IEC Standard 17025 to perform 

testing using the test methods specified under §60.534.

(2) As part of the application, the test laboratory must:

(i) Agree to enter into a contract as described in §60.533(e) with each wood heater 

manufacturer for whom a certification test has been performed;

(ii) Agree to participate biennially in a proficiency testing program conducted by

the Administrator;

(iii) Agree to allow the Administrator and delegated states and certifying bodies 

access to observe certification testing;

(iv) Agree to comply with reporting and recordkeeping requirements that affect 

testing laboratories; and

(v) Agree to perform a compliance audit test (as determined by the Administrator) 

at the cost normally charged to manufacturers if it is selected to conduct the compliance 

audit test of a model line originally tested for certification at another laboratory.
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(vi) Have no conflict of interest and receive no financial benefit from the outcome 

of certification testing conducted pursuant to §60.533.

(vii) Agree to not perform initial certification tests on any models manufactured 

by a manufacturer for which the laboratory has conducted research and development tests 

within the last 5 years.

(3) If the EPA approves the accreditation, the Administrator will provide the test 

laboratory with a certificate of accreditation. If the EPA denies the accreditation, the 

Administrator will give written notice to the laboratory setting forth the basis for the 

determination.

(b)(1) The Administrator may revoke the EPA laboratory accreditation if it is

determined that the laboratory:

(i) Is no longer is accredited by the nationally recognized ISO certifying entity;

(ii) Does not follow required procedures or practices;

(iii) Has falsified data or otherwise misrepresented emission data;

(iv) Failed to participate in a proficiency testing program, in accordance with its 

commitment under paragraph (a)(2)(ii) of this section; or

(v) Failed to seal the wood heater in accordance with paragraph (d) of this section.

(2) Revocation of accreditation under this paragraph will not take effect until the 

laboratory concerned has been given written notice by the Administrator setting forth the 

basis for the proposed determination and an opportunity for a Petition for Supplemental 

Review under §60.539. However, if revocation is ultimately upheld, all tests conducted 

by the laboratory after written notice was given will, at the discretion of the 

Administrator, be declared invalid.
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(c)(1) With the exception of laboratories meeting the provisions of paragraph 

(c)(2) of this section, and unless revoked sooner, a certificate of accreditation as an 

accredited test laboratory granted by the Administrator is valid for 5 years from the date 

of issuance.

(2) Laboratories accredited by the EPA by [INSERT DATE OF 

PUBLICATION OF THE PROPOSED RULE IN THE FEDERAL REGISTER] 

under the provisions of §60.535 in effect prior to that date may continue to be accredited 

until [1 YEAR AFTER EFFECTIVE DATE OF FINAL RULE], at which time the 

accreditation ends unless the laboratory has obtained accreditation under §60.535 as in 

effect beginning on [EFFECTIVE DATE OF FINAL RULE].

(d) A laboratory accredited by the Administrator must seal any wood heater on 

which it performed certification tests, immediately upon completion or suspension of 

certification testing, by using a laboratory-specific seal. For any tests that are suspended, 

the laboratory must email the EPA immediately with the date suspended, the reason(s) 

why, and the projected date for re-starting. The laboratory must submit the operation and 

test data obtained, even if the test is not completed. 

(e)(1) A Certifying Entity may apply to the Administrator for approval to be an 

EPA -approved certifying entity by submitting credentials demonstrating that they have 

been accredited by a nationally recognized accrediting entity to perform certifications and 

inspections under ISO-17025, ISO-IEC Standard 17065 and ISO-IEC Standard 10720.

(2) As part of the application, the certifying entity must:
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(i) Agree to enter into a contract as described in §60.533(e) with each wood heater 

manufacturer for whom a certification test has been performed and a test report has been 

received and reviewed;

(ii) Agree to periodically conduct audits as described in §60.534 and 

manufacturer’s QA/QC Plan;

(iii) Agree to participate biennially in a proficiency testing program conducted 

by the Administrator;

(iv) Agree to comply with reporting and recordkeeping requirements that affect

accredited wood heater testing laboratories and certifying entities;

(v) Have no conflict of interest and receive no financial benefit from the outcome 

of certification testing conducted pursuant to §60.533; 

(vi) Agree to make available to the EPA supporting documentation for each 

wood heater certification and audit; and

(vii) Agree to not perform initial certification reviews on any models 

manufactured by a manufacturer for which the certifying entity has conducted research 

and development within the last 5 years.

(3) If approved, the Administrator will provide the certifying entity with a 

certificate of accreditation. The accreditation will expire 5 years after being issued unless 

renewed by the certifying entity. If the EPA denies the accreditation, the Administrator 

will give written notice to the certifying entity for the basis for the determination.

(f)(1) The Administrator will revoke the EPA certifying entity accreditation if it is 

determined that the certifying entity;

(i) Is no longer accredited by the nationally recognized ISO certifying entity
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(ii) Does not follow required procedures or practices;

(iii) Has falsified certification data or otherwise misrepresented emission data; or

(iv) Failed to participate in the EPA proficiency testing program.

(2) Revocation of accreditation under this paragraph will not take effect until the 

certifying entity concerned is given written notice by the Administrator setting forth the 

basis for the proposed determination and an opportunity for a Petition for Supplemental 

Review under 60.539. However, if revocation is upheld, all tests reviewed by the 

certifying entity will, at the discretion of the Administrator, be declared invalid.

§60.536 What requirements must I meet for permanent labels and owner's manuals?

(a) Permanent Label Requirements.

(1) Each affected wood heater manufactured on or after the date the applicable 

standards come into effect as specified in §60.532, must have a permanent label affixed 

to it that meets the requirements of this section.

(2) Except for wood heaters subject to §60.530(b)(1) through (b)(5), the 

permanent label must contain the following information:

(i) Month and year of manufacture of the individual unit;

(ii) Model name or number; and

(iii) Serial number.

(3) The permanent label must:

(i) Be affixed in a readily visible or accessible location in such a manner that it 

can be easily viewed before and after the appliance is installed;

(ii) Be at least 8.9 cm long and 5.1 cm wide (3 1/2 inches long and 2 inches wide);

(iii) Be made of a material expected to last the lifetime of the wood heater;
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(iv) Present required information in a manner so that it is likely to remain legible 

for the lifetime of the wood heater; and

(v) Be affixed in such a manner that it cannot be removed from the appliance 

without damage to the label.

(4) The permanent label may be combined with any other label, as long as the 

required information is displayed, the integrity of the permanent label is not 

compromised, and the permanent label still meets the requirements in §60.536(a)(3).

(5) Any label statement under paragraph (b) or (c) of this section constitutes a 

representation by the manufacturer as to any wood heater that bears it:

(i) That certification of compliance was in effect at the time the wood heater left 

the possession of the manufacturer;

(ii) That the manufacturer was, at the time the label was affixed, conducting a 

quality assurance program in conformity with §60.533(o); and

(iii) That any wood heater individually tested for emissions by the manufacturer 

under §60.533(o)(2) or (o)(4) met the applicable emissions limits.

(b) If the adjustable burn rate wood heater or pellet stove belongs to a model line 

certified under §60.533, and it has been found to meet the applicable emission limits or 

tolerances through quality assurance testing, one of the following statements, as 

appropriate, must appear on the permanent label:

U.S. ENVIRONMENTAL PROTECTION AGENCY

Certified to comply with 1990 particulate emission standards.

Not approved for sale or operation after [6 MONTHS AFTER EFFECTIVE DATE OF 

FINAL RULE]
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or

U.S. ENVIRONMENTAL PROTECTION AGENCY

Certified to comply with 2014 particulate emission standards.

Not approved for sale or operation after [5 YEARS AFTER EFFECTIVE DATE OF 

FINAL RULE]

or

U.S. ENVIRONMENTAL PROTECTION AGENCY

Certified to comply with 2019 particulate emission standards.

(c) If the single burn rate wood heater belongs to a model line certified under 

§60.533, and it has been found to meet the applicable emission limits or tolerances 

through quality assurance testing, the following statements must appear on the permanent 

label:

U.S. ENVIRONMENTAL PROTECTION AGENCY

Certified to comply with 2014 particulate emission standards.

Not approved for sale or operation after [5 YEARS AFTER EFFECTIVE DATE OF 

FINAL RULE]

or

U.S. ENVIRONMENTAL PROTECTION AGENCY

Certified to comply with 2019 particulate emission standards.

(d)(1) If an affected wood heater is manufactured in the United States for export 

as provided in §60.530(b)(1), the following statement must appear on the permanent 

label:

U.S. ENVIRONMENTAL PROTECTION AGENCY
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Export stove. May not be sold or operated within the United States.

(2) If an affected wood heater is manufactured for use for research and 

development purposes as provided in §60.530(b)(2), the following statement must appear 

on the permanent label:

U.S. ENVIRONMENTAL PROTECTION AGENCY

Not certified. Research Stove. Not approved for sale or for operation other than research.

(3) If an affected wood heater is exclusively a non wood-burning heater as 

provided §60.530(b)(3) the following statement must appear on the permanent label:

U.S. ENVIRONMENTAL PROTECTION AGENCY

This heater is not certified for wood burning. Use of any wood fuel is a violation of 

federal law.

(4) If an affected wood heater is a cookstove that meets the applicable definition 

in §60.531, the following statement must appear on the permanent label:

U.S. ENVIRONMENTAL PROTECTION AGENCY

This unit is not a certified residential wood heater. The primary use for this unit is for 

cooking or baking.

(5) If an affected wood heater is a camp stove that meets the applicable definition 

in §60.531, the following statement must appear on the permanent label:

U.S. ENVIRONMENTAL PROTECTION AGENCY

This unit is not a certified residential wood heater. For portable and temporary use only.

(e) The permanent label for all certified wood heaters must also contain the 

following statement:
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“This wood heater needs periodic inspection and repair for proper operation. Consult 

owner's manual for further information. It is against the law to operate this wood heater 

in a manner inconsistent with operating instructions in the owner's manual.”

(f) Owner’s Manual.

(1) Each affected wood heater offered for sale by a commercial owner must be 

accompanied by an owner's manual that must contain the information listed in paragraphs

(f)(2) and (f)(3) of this section. Such information must be adequate to enable consumers 

to achieve optimal emissions performance. Such information must be consistent with the 

operating instructions provided by the manufacturer to the accredited test laboratory for 

operating the wood heater during certification testing, except for details of the 

certification test that would not be relevant to the ultimate purchaser. The commercial 

owner must also make current and historical owner’s manuals available on the company 

website and upon request to the EPA.

(2) Installation information: Requirements for achieving proper draft.

(3) Operation and maintenance information:

(i) Fuel loading procedures, recommendations on fuel selection, and warnings on 

what fuels not to use, such as treated wood, colored paper, cardboard, solvents, trash and 

garbage.

(ii) Fire starting procedures

(iii) Proper use of air controls

(iv) Ash removal procedures
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(v) Instructions for replacement of gaskets, air tubes and other parts that are 

critical to the emissions performance of the unit and other maintenance and repair 

instructions

(vi) For catalytic models, information on the following pertaining to the catalytic 

combustor: Procedures for achieving and maintaining catalyst activity, maintenance 

procedures, procedures for determining deterioration or failure, procedures for 

replacement, and information on how to exercise warranty rights

(vii) For catalytic models, the following statement—

“This wood heater contains a catalytic combustor, which needs periodic inspection and 

replacement for proper operation. It is against federal law to operate this wood heater in a 

manner inconsistent with operating instructions in this manual, or if the catalytic element 

is deactivated or removed.”

(viii) For noncatalytic models, the following statement—

“This wood heater needs periodic inspection and repair for proper operation. It is against 

federal law to operate this wood heater in a manner inconsistent with operating 

instructions in this manual.”

(4) Any manufacturer using the EPA-recommended language contained in 

appendix I of this part to satisfy any requirement of this paragraph (f) will be considered 

to be in compliance with that requirement, provided that the particular language is printed 

in full, with only such changes as are necessary to ensure accuracy for the particular 

wood heater model line.
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(i) Wood heaters that are affected by this subpart, but that have been owned and 

operated by a noncommercial owner, are not subject to paragraphs (g) and (h) of this 

section when offered for resale.

§60.537 What records must I keep and what reports must I submit?

(a)(1) Each manufacturer who holds a certificate of compliance under §60.533(c) 

or (f) for a model line must maintain records containing the information required by this 

paragraph (a) with respect to that model line. 

(2) All documentation pertaining to the certification test used to obtain 

certification, including the full test report and raw data sheets, laboratory technician 

notes, calculations, and the test results for all test runs.

(3) Results of the quality assurance program inspections required by §60.533(m).

(4) For emissions tests conducted pursuant to the quality assurance program 

required by §60.533(o), all test reports, data sheets, laboratory technician notes, 

calculations, and test results for all test runs, the remedial actions taken, if any, and any

follow-up actions such as additional testing.

(b) Each accredited test laboratory and certifying entity must maintain records 

consisting of all documentation pertaining to each certification test, QA/QC inspection 

and audit test, including the full test report and raw data sheets, technician notes, 

calculations, and the test results for all test runs. Each accredited test laboratory must 

submit initial and biennial proficiency test results to the Administrator. Each certifying 

entity must submit each certification test, QA/QC inspection report and ISO IEC 

accreditation credentials to the Administrator.
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(c) Each manufacturer must retain each wood heater upon which certification tests 

were performed based upon which certification was granted under §60.533(c) or (f) at the 

manufacturer's facility for as long as the model line in question is manufactured. Each 

heater or furnace must remain sealed and unaltered. Any such wood heater must be made 

available to the Administrator upon request for inspection and testing.

(d) Each manufacturer of an affected wood heater certified under §60.533(c) or (f) 

must submit a report to the Administrator every 2 years following issuance of a certificate 

of compliance for each model line. This report must include the sales for each model by

state and certify that no changes in the design or manufacture of this model line have 

been made that require recertification under §60.533(k).

(e)(1) Unless otherwise specified, all records required under this section must be 

maintained by the manufacturer, commercial owner of the affected wood heater, 

accredited test laboratory or certifying entity for a period of no less than 5 years.

(2) Unless otherwise specified, all reports to the Administrator required under this 

subpart must be made to: XXXX Compliance Program at xxxx.gov/yyyy.

(f) Within 60 days after the date of completing each performance test, each 

manufacturer or accredited test laboratory or certifying entity must submit performance 

test data electronically to the EPA’s Central Data Exchange (CDX) by using the 

Electronic Reporting Tool (ERT) (http://www.epa.gov/ttn/chief/ert/index.html). Only

data collected using test methods compatible with ERT are subject to this requirement to 

be submitted electronically to the EPA’s CDX. Owners or operators who claim that some 

of the information being submitted for performance tests is confidential business 

information (CBI) must submit a completed ERT file, including information claimed to 
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be CBI on a compact disk or other commonly used electronic storage media (including, 

but not limited to, flash drives), to the EPA, and the same ERT file, with the CBI omitted,

to the EPA via CDX as described earlier in this paragraph. The compact disk must be 

clearly marked as CBI and mailed to U.S. EPA/OAQPS/CORE CBI Office, Attention: 

WebFIRE Administrator, MD C404-02, 4930 Old Page Rd., Durham, NC 27703. 

Emission data, including all information necessary to determine compliance, except 

sensitive engineering drawings and sensitive detailed material specifications, may not be 

claimed as CBI.

§60.538 What activities are prohibited under this subpart?

(a) No person is permitted to operate an affected wood heater that does not have 

affixed to it a permanent label pursuant to §60.536 (b), (c), or (d)(2) through (d)(5).

(b) No commercial owner is permitted to advertise for sale, offer for sale, or sell 

an affected wood heater labeled under §60.536(d)(1) except for export.

(c)(1) No commercial owner is permitted to advertise for sale, offer for sale or sell 

an affected wood heater permanently labeled under §60.536 (b) or (c) unless:

(i) The affected wood heater has been certified to comply with 2019 particulate 

emission standards. This prohibition does not apply to wood heaters affected by this 

subpart that have been previously owned and operated by a noncommercial owner; and

(ii) The commercial owner provides any purchaser or transferee with an owner's 

manual that meets the requirements of §60.536(f), a copy of the warranty and a moisture 

meter.

(2) No commercial owner is permitted to advertise for sale, offer for sale, or sell 

an affected wood heater permanently labeled under §60.536(d)(3), unless the affected 
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wood heater has been certified to comply with 2019 particulate emission. This 

prohibition does not apply to wood heaters affected by this subpart that have been 

previously owned and operated by a noncommercial owner.

(3) A commercial owner other than a manufacturer complies with the 

requirements of paragraph (c)(1) of this section if the commercial owner—

(i) Receives the required documentation from the manufacturer or a previous 

commercial owner; and

(ii) Provides that documentation unaltered to any person to whom the wood heater 

that it covers is sold or transferred.

(d)(1) In any case in which the Administrator revokes a certificate of compliance 

either for the knowing submission of false or inaccurate information or other fraudulent 

acts, or based on a finding under §60.533(l)(1)(ii) that the certification test was not valid, 

the Administrator may give notice of that revocation and the grounds for it to all 

commercial owners.

(2) On and after the date of receipt of the notice given under paragraph (d)(1) of 

this section, no commercial owner is permitted to sell any wood heater covered by the 

revoked certificate (other than to the manufacturer) unless the model line has been 

recertified in accordance with this subpart.

(e) No person is permitted to install or operate an affected wood heater except in a 

manner consistent with the instructions on its permanent label and in the owner's manual 

pursuant to §60.536(f).

(f) No person is permitted to operate an affected wood heater that was originally 

equipped with a catalytic combustor if the catalytic element is deactivated or removed.
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(g) No person is permitted to operate an affected wood heater that has been 

physically altered to exceed the tolerance limits of its certificate of compliance.

(h) No person is permitted to alter, deface, or remove any permanent label 

required to be affixed pursuant to §60.536.

(i) No certifying entity is permitted to certify its own certification test report.

§60.539 What Petition for Review procedures apply to me?

(a)(1) In any case where the Administrator—

(i) Denies an application under §60.530(c) or §60.533(f);

(ii) Issues a notice of revocation of certification under §60.533(l);

(iii) Denies an application for laboratory accreditation under §60.535(a); or

(iv) Issues a notice of revocation of laboratory accreditation under §60.535(b), the 

manufacturer or laboratory affected may submit to the EPA, a Petition for Review request 

under this section within 30 days following receipt of the required notification of the 

action in question.

(2) In any case where the Administrator issues a notice of revocation under 

§60.533(p), the manufacturer may submit to the EPA a Petition for Review request under 

this section with the time limits set out in §60.533(p)(4).

(b) Any Petition for Review request must be in writing, must be signed by an 

authorized representative of the petitioning manufacturer or laboratory, and must include 

a statement and supporting documentation setting forth with particularity the petitioner's 

objection to the Administrator's determination or proposed determination.

(c) Upon receipt of a Petition for Review under paragraph (a) of this section, the 

Administrator shall provide a written response within 45 days.
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§60.539a Who implements and enforces this subpart?

(a) In delegating implementation and enforcement authority to a state under 

section 111(c) of the Act, the authorities contained in paragraph (b) of this section must 

be retained by the Administrator and not transferred to a state.

(b) Authorities that must not be delegated to states:

(1) Section 60.531, Definitions;

(2) Section 60.533, Compliance and certification;

(3) Section 60.534, Test methods and procedures; and

(4) Section 60.535, Laboratory accreditation.

§60.539b What parts of the General Provisions do not apply to me?

The following provisions of subpart A of part 60 do not apply to this subpart:

(a) Section 60.7;

(b) Section 60.8(a), (c), (d), (e), (f) and (g); and

(c) Section 60.15(d).

4. Part 60 is amended by adding subpart QQQQ to read as follows:

Subpart QQQQ – Standards of Performance for New Residential Hydronic Heaters 

and Forced-Air Furnaces

Sec.

60.5472 Am I subject to this subpart?

60.5473 What definitions must I know?

60.5474 What standards and requirements must I meet and by when?

60.5475 What compliance and certification requirements must I meet and by when?
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60.5476 What test methods and procedures must I use to determine compliance with the 

standards and requirements for certification?

60.5477 What procedures must I use for laboratory accreditation?

60.5478 What requirements must I meet for permanent labels and owner's manuals?

60.5479 What records must I keep and what reports must I submit?

60.5480 What activities are prohibited under this subpart?

60.5481 What Petition for Review procedures apply to me?

60.5482 Who implements and enforces this subpart?

60.5483 What parts of the General Provisions do not apply to me?

Subpart QQQQ – Standards of Performance for New Residential Hydronic Heaters 

and Forced-Air Furnaces

§60.5472 Am I subject to this subpart?

(a) You are subject to this subpart if you operate, manufacture, sell, offer for sale, 

import for sale, distribute, offer to distribute, introduce, or deliver for introduction, into 

commerce in the United States, residential hydronic heater or forced-air furnace 

manufactured on or after [EFFECTIVE DATE OF FINAL RULE]. 

(b) Each residential hydronic heater or forced-air furnace must comply with the 

provisions of this subpart unless exempted under paragraphs (b)(1) through (b)(3) of this 

section.

(1) Affected residential hydronic heaters or forced-air furnaces manufactured in 

the United States for export are exempt from the applicable emission limits of §60.5474 

and the requirements of §60.5475.
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(2) Affected residential hydronic heaters or forced-air furnaces used for research 

and development purposes that are never offered for sale or sold and that are not used to 

provide heat are exempt from the applicable emission limits of §60.5474 and the 

requirements of §60.5475. No more than 12 affected residential hydronic heaters or 

forced-air furnaces manufactured per model line may be exempted for this purpose.

(3) Appliances that do not burn wood or wood pellets (such as coal-only hydronic 

heaters or forced-air furnaces that meet the definition in §60.5473 or corn-only hydronic 

heaters or forced-air furnaces) are exempt from the applicable emission limits of 

§60.5474 and the requirements of §60.5475. 

(c) The following are not affected residential hydronic heaters or forced-air 

furnaces and are not subject to this subpart: 

(1) Residential wood heaters subject to subpart AAA of this part.

(2) Residential masonry heaters subject to subpart RRRR of this part.

§60.5473 What definitions must I know?

As used in this subpart, all terms not defined herein have the same meaning given 

them in the Clean Air Act and subpart A of this part.

Accredited test laboratory means a test laboratory that is accredited for residential 

hydronic heater or forced-air furnace certification testing under §60.5477 and is an

independent third-party test laboratory that is accredited by a nationally recognized 

accrediting entity under ISO-IEC Standard 17025 to perform testing using the test 

methods specified in §60.5476 and approved by the EPA for conducting certification 

tests under this subpart.
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At retail means the sale by a commercial owner of a residential hydronic heater or 

forced-air furnace to the ultimate purchaser.

Central heater means a fuel-burning device designed to burn wood or wood pellet 

fuel that warms spaces other than the space where the device is located, by the 

distribution of air heated by the furnace through ducts or liquid heated in the device and 

distributed typically through pipes. Unless otherwise specified, these devices include 

residential forced-air furnaces and residential hydronic heaters.

Certifying entity means an independent third party that is accredited by a 

nationally recognized accrediting entity under ISO-IEC Standard 17020 to perform 

certifications, inspections and audits under ISO-IEC Guide 17065 and approved by the 

EPA for conducting certifications, inspections and audits under this subpart. 

Coal-only hydronic heater or forced-air furnace means an enclosed, coal-burning 

appliance capable of space heating or domestic water heating that has all of the following 

characteristics:

(1) Installation instructions that state that the use of wood in the appliance, except 

for coal ignition purposes, is prohibited by law; and

(2) The model is listed by a nationally recognized safety-testing laboratory for 

coal use only, except for coal ignition purposes.

Commercial owner means any person who owns or controls a residential hydronic 

heater or forced-air furnace in the course of the business of the manufacture, importation, 

distribution, or sale of the unit.

Manufactured means completed and ready for shipment (whether or not 

packaged) for purposes of determining the date of manufacture.
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Manufacturer means any person who constructs or imports into the United States 

a residential hydronic heater or forced-air furnace.

Model line means all residential hydronic heaters or forced-air furnaces offered 

for sale by a single manufacturer that are similar in all material respects as defined in this 

section. 

Particulate matter (PM) means total particulate matter including PM10 and PM2.5.

Pellet fuel means refined and densified solid wood shaped into small pellets or 

briquettes that are uniform in size, shape, moisture, density and energy content. 

Representative residential hydronic heater or forced-air furnace means an 

individual residential hydronic heater or forced-air furnace that is similar in all material 

respects as defined in this section to other residential hydronic heaters or forced-air 

furnaces within the model line it represents.

Residential forced-air furnace means a fuel burning device designed to burn 

wood or wood pellet fuel that warms spaces other than the space where the furnace is 

located, by the distribution of air heated by the furnace through ducts. 

Residential hydronic heater means a fuel burning device designed to burn wood 

or wood pellet fuel for the purpose of heating building space and/or water through the 

distribution, typically through pipes, of a fluid heated in the device, typically water or a 

water and antifreeze mixture.

Sale means the transfer of ownership or control, except that a transfer of control 

of an affected residential hydronic heater or forced-air furnace for research and 

development purposes within the scope of §60.5472(b)(2) is not a sale.

Seasoned wood means wood with a moisture content of 20 percent or less.
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Similar in all material respects means that the construction materials, exhaust and 

inlet air system, and other design features are within the allowed tolerances for 

components identified in §60.533(k).

Valid certification test means a test that meets the following criteria:

(1) The Administrator was notified about the test in accordance with §60.5476(f);

(2) The test was conducted by an accredited test laboratory as defined in this 

section;

(3) The test was conducted on a residential hydronic heater or forced-air furnace 

similar in all material respects as defined in this section to other residential hydronic 

heaters or forced-air furnaces of the model line that is to be certified; and 

(4) The test was conducted in accordance with the test methods and procedures 

specified in §60.5476.

§60.5474 What standards and requirements must I meet and by when?

(a) Particulate Matter Standards. Unless exempted under §60.5472, no person is 

permitted to:

(1) On or after [EFFECTIVE DATE OF FINAL RULE], manufacture or sell at 

retail a residential hydronic heater unless it has been certified to meet the 2014 particulate 

matter emission limits in paragraph (b)(1) of this section. 

(2) On or after [5 YEARS AFTER EFFECTIVE DATE OF FINAL RULE]

manufacture or sell at retail a residential hydronic heater unless it has been certified to 

meet the 2019 particulate matter emission limit in paragraph (b)(2) of this section. 
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(3) On or after [EFFECTIVE DATE OF FINAL RULE], manufacture or sell at 

retail a residential forced-air furnace unless it has been certified to meet the 2014

particulate matter emission limits in paragraph (b)(3) of this section. 

(4) On or after [5 YEARS AFTER EFFECTIVE DATE OF FINAL RULE]

manufacture or sell at retail a residential forced-air furnace unless it has been certified to 

meet the 2019 particulate matter emission limit in paragraph (b)(4) of this section. 

(b)(1) 2014 residential hydronic heater particulate matter emission limit: 0.32

lb/million Btu (0.137 g/megajoule) heat output and 7.5 g/hr (0.017 lb/hr) as determined 

by the test methods and procedures in §60.5476.

(2) 2019 residential hydronic heater particulate matter emission limit: 0.06 

lb/million Btu (0.026 g/megajoule) heat output as determined by the test methods and 

procedures in §60.5476.

(3) 2014 forced-air furnace particulate matter emission limit: 0.93 lb/million Btu 

(0.40 g/megajoule) heat output and 7.5 g/hr (0.017 lb/hr) as determined by the test 

methods and procedures in §60.5476.

(4) 2019 forced-air furnace particulate matter emission limit: 0.06 lb/million Btu 

(0.026 g/megajoule) heat output as determined by the test methods and procedures in 

§60.5476.

(c) [Reserved]

(d) [Reserved]

(e) Pellet Fuel Requirements. Operators of outdoor residential hydronic heaters, 

indoor residential hydronic heaters, or residential forced-air furnaces that are certified to 

burn pellet fuels may only burn pellets that have been produced under a licensing 
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agreement with the Pellet Fuels Institute or an equivalent organization approved by the 

EPA. The pellet fuel must meet the following minimum requirements:

(1) Density: consistent hardness and energy content with a minimum density of 38 

pounds/cubic foot; 

(2) Dimensions: maximum length of 1.5 inches and diameter between 0.230 and 

0.285 inches; 

(3) Inorganic fines: less than or equal to 1 percent;

(4) Chlorides: less than or equal to 300 parts per million by weight; and 

(5) Ash content: no more than 2 percent.

(6) A quality assurance process licensed by the Pellet Fuel Institute or equivalent 

organization approved by EPA.

(f) Prohibited Fuel Types. No person is permitted to burn any of the following 

materials in an outdoor residential hydronic heater, indoor residential hydronic heater, or 

residential forced-air furnace:

(1) Residential or commercial garbage;

(2) Lawn clippings or yard waste;

(3) Materials containing rubber, including tires;

(4) Materials containing plastic;

(5) Waste petroleum products, paints or paint thinners, or asphalt products;

(6) Materials containing asbestos;

(7) Construction or demolition debris;

(8) Paper products; cardboard, plywood or particleboard. The prohibition against 

burning these materials does not prohibit the use of fire starters made from paper, 
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cardboard, saw dust, wax and similar substances for the purpose of starting a fire in an 

affected residential hydronic heater or forced-air furnace;

(9) Railroad ties or pressure treated lumber;

(10) Manure or animal remains; 

(11) Salt water driftwood or other or other previously salt water saturated 

materials;

(12) Unseasoned wood; or 

(13) Any materials that were not included in the certification tests for the subject 

heater or furnace.

(g) Owner’s Manual. A person must not operate an outdoor residential hydronic 

heater, indoor residential hydronic heater, or residential forced-air furnace in a manner 

inconsistent with the owner’s manual. The owner’s manual must clearly specify that 

operation in a manner inconsistent with the owner’s manual would violate the warranty. 

§60.5475 What compliance and certification requirements must I meet and by when?

(a)(1) Certification Requirement. Each affected residential hydronic heater and 

forced-air furnace must be certified to be in compliance with the applicable emission 

standards and other requirements of this subpart. For each model line manufactured or 

sold by a single entity, e.g., company or manufacturer, compliance with applicable 

emission standards of §60.5474(b) must be determined based on testing of representative 

affected residential hydronic heaters and forced-air furnaces within the model line. If one 

entity licenses a model line to another entity, each entity’s model line must be certified. If 

a entity changes the name of the entity or the name of the model, the manufacturer must 

apply for a new certification.
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(2) The manufacturer of each model line must submit the information required in 

§60.533(b) and follow the certification procedure specified in §60.533(f) except that, for 

the purposes of this paragraph, the references in §60.533(f) to the “emission standards” in 

§60.532 must be understood to refer to the emission limits in §60.5474(b).

(b) Waiver from Submitting Test Results. An applicant for certification may apply

for a potential waiver of the requirements to submit the results of a certification test 

pursuant to the certification procedures specified in §60.533(f) according to the procedure 

specified in §60.533(g)(1).

(c) Certification Period. Unless revoked sooner by the Administrator, a certificate 

of compliance will be valid 5 years from the date of issuance.

(d) Renewal of Certification.

(1) Any manufacturer of an affected residential hydronic heater or forced-air 

furnace may apply to the Administrator for potential renewal of a certificate of 

compliance by submitting the material specified in §60.533(b) and following the 

procedures specified in §60.533(f). 

(2) The certificate must be recertified or renewed every 5 years or the 

manufacture may choose to no longer manufacture or sell that model. If the manufacturer 

chooses to no longer manufacture or sell that model, then the manufacturer must submit a 

statement to the EPA for that model. A manufacturer may apply for potential renewal of

their certificate by submitting certification information in accordance with §60.533(b) or 

by affirming in writing that the wood heater has been subject to no changes that would 

impact emissions and request a potential waiver from certification testing.
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(3) If the Administrator grants or waives certification testing under paragraph 

(d)(2) of this section, the Administrator will give written notice to the manufacturer 

setting forth the basis for the determination and issue a certification renewal.

(4) If the Administrator denies the request for a renewal of certification, the 

Administrator will give written notice to the manufacturer setting forth the basis for the 

determination.

(e) Recertification. The procedure specified in §60.533(k) must be used to 

determine when a product line must be recertified.

(f) Criteria for Revocation of Certification. 

(1) The Administrator may revoke certification of a product line if it is

determined that the residential hydronic heaters or forced-air furnaces being 

manufactured or sold in that model line do not comply with the requirements of this 

subpart. Such a determination will be based on all available evidence, including but not 

limited to:

(i) Test data from retesting of the original unit on which the certification was 

conducted or a similar unit;

(ii) A finding that the certification test was not valid. The finding will be based on 

problems or irregularities with the certification test or its documentation, but may be 

supplemented by other information;

(iii) A finding that the labeling of the residential hydronic heater or forced-air 

furnace model line or the owner’s manual or marketing information does not comply with 

the requirements of §60.5478;
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(iv) Failure by the manufacturer to comply with the reporting and recordkeeping 

requirements of §60.5479;

(v) Physical examination showing that a significant percentage (as defined in the 

quality assurance plan, but no larger than 1 percent) of production units inspected is not 

similar in all material respects as defined in this subpart to the representative affected

hydronic heater or forced-air furnace submitted for testing; or

(vi) Failure of the manufacturer to conduct a quality assurance program in 

conformity with paragraph (g) of this section.

(2) Revocation of certification under this paragraph will not take effect until the 

manufacturer concerned has been given written notice by the Administrator setting forth 

the basis for the proposed determination and an opportunity to request a review under 

§60.5481.

(g) Quality Assurance Program. For each certified model line, the manufacturer 

must conduct a quality assurance program according to the requirements of §60.533(m).

(h) EPA Compliance Audit Testing. The Administrator will conduct compliance 

audit testing according to the requirements of §60.533(n). For the purposes of this 

paragraph, references in §60.533(n) to §§60.532 through 60.535 must be understood to 

refer to the comparable paragraphs in §§60.5474 through 60.5477 and the associated test 

methods specified in this subpart. 

§60.5476 What test methods and procedures must I use to determine compliance with the 

standards and requirements for certification?
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Test methods and procedures specified in this section or in appendix A of this 

part, except as provided under §60.8(b), must be used to determine compliance with the 

standards and requirements for certification under §§60.5474 and 60.5475 as follows:

(a)(1) Method 28 WHH must be used to measure the heat output (million Btu/hr) 

of outdoor and indoor residential hydronic heaters.

(2) If the model is subject to the 2014 particulate matter standards specified in 

§60.5474(a)(1) and is equipped with an external heat storage unit, you must conduct 

testing according to paragraph §60.5476(a)(2)(i) and (ii) of this section. You have the 

option of submitting the test results of either (a)(2)(i) or (ii) of this section to the 

Administrator as specified under §60.5479 for certification compliance.

(i) Conduct testing using crib wood as specified in Method 28 WHH. The heat 

input and heat output measurements must be performed according to ASTM method 

E2618-09 entitled “Standard Test Method for Determining Particulate Matter Emissions 

and Heating of Outdoor Solid Fuel-fired Hydronic Heating Appliances.” Testing 

conducted with continuously fed biomass as the fuel(s) must be conducted according to 

the relevant section of the ASTM method.

(ii) Conduct testing using cord wood as specified in “A Test Method for 

Certification of Cord Wood-Fired Hydronic Heating Appliances with Partial Thermal 

Storage: Measurement of Particulate Matter (PM) and Carbon Monoxide (CO) Emissions 

and Heating Efficiency of Wood-Fired Hydronic Heating Appliances with Partial 

Thermal Storage.”

(3) If the model is subject to the 2019 particulate matter standards specified in 

§60.5474(a)(2) and is equipped with an external partial heat storage unit, you must 
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conduct cord wood testing according to the test methods and procedures of “A Test 

Method for Certification of Cord Wood-Fired Hydronic Heating Appliances with Partial 

Thermal Storage: Measurement of Particulate Matter (PM) and Carbon Monoxide (CO) 

Emissions and Heating Efficiency of Wood-Fired Hydronic Heating Appliances with 

Partial Thermal Storage.”

(b) Method 28 WHH in conjunction with ASTM E2515-10 must be used to 

measure the particulate matter emission rate (lb/million Btu heat output) of outdoor and 

indoor residential hydronic heaters, except that for the 2019 standards, you should first 

test Burn Rate Categories 1 and 4 and then test 2 more times for whichever burn rate 

category is worse on a lb/million BTU heat output basis and report the results separately 

per burn rate category.

(c) Canadian Standards Administration (CSA) Method B415.1-10 must be used 

to measure the heat output (million Btu/hr) and particulate matter emission rate 

(lb/million Btu heat output) of forced-air furnaces, except that for the 2019 standards, you 

should first test Burn Rate Categories 1 and 4 and then test 2 more times for whichever 

burn rate category is worse on a lb/million BTU heat output basis and report the results 

separately per burn rate category.

(d) CSA Method B415.1-10, section 13.7, must be used to measure the thermal 

efficiency of outdoor and indoor residential hydronic heaters.

(e) [Reserved]

(f) The manufacturer of an affected residential hydronic heater or forced-air 

furnace must notify the Administrator of the date that certification testing is to begin, by

email, to XXXX Compliance Program at xxx.gov/yyyy. This notice must be at least 30 
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days before the start of testing. The notification of testing must include the 

manufacturer’s name and address, the accredited test laboratory’s name and address, 

certifying entity name, the model name and number (or, if unavailable, some other way to 

distinguish between models), and the dates of testing.

(g) The accredited test laboratory must allow the manufacturer, the EPA and 

delegated states to observe certification testing. However, manufacturers must not 

involve themselves in the conduct of the test after the pretest burn (as defined by EPA 

Method 28 WHH) has begun. Communications between the manufacturer and laboratory

or certifying entity personnel regarding operation of the hydronic heater must be limited 

to written communications transmitted prior to the first pretest burn of the certification 

series. Written communications between the manufacturer and laboratory personnel may

be exchanged during the certification test only if deviations from the test procedures are 

observed that constitute improper conduct of the test. All communications must be 

included in the test documentation required to be submitted pursuant to §60.533(b)(3) 

and must be consistent with instructions provided in the owner's manual required under 

§60.5478(f), except to the extent that they address details of the certification tests that 

would not be relevant to owners.

§60.5477 What procedures must I use for laboratory accreditation?

The accreditation procedure specified in §60.535 must be used to certify test 

laboratories under this subpart.

§60.5478 What requirements must I meet for permanent labels and owner's manuals?

(a) Permanent Label Requirements.
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(1) Each affected residential hydronic heater or forced-air furnace manufactured 

or sold on or after the date the applicable standards come into effect as specified in 

§60.5474, must have a permanent label affixed to it that meets the requirements of this 

section.

(2) The permanent label must contain the following information:

(i) Month and year of manufacture of the individual unit;

(ii) Model name or number; and

(iii) Serial number.

(3) The permanent label must:

(i) Be affixed in a readily visible or accessible location in such a manner that it 

can be easily viewed before and after the appliance is installed;

(ii) Be at least 8.9 cm long and 5.1 cm wide (3 1/2 inches long and 2 inches wide);

(iii) Be made of a material expected to last the lifetime of the residential hydronic 

heater or forced-air furnace;

(iv) Present required information in a manner so that it is likely to remain legible 

for the lifetime of the residential hydronic heater or forced-air furnace; and

(v) Be affixed in such a manner that it cannot be removed without damage to the 

label.

(4) The permanent label may be combined with any other label, as long as the 

required information is displayed, the integrity of the permanent label is not 

compromised, and the requirements of §60.5478(a)(3) are still met.

(b) If the residential hydronic heater or forced-air furnace belongs to a model line 

certified under §60.5475, and it has been found to meet the applicable emission limits or 
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tolerances through quality assurance testing, one of the following statements, as 

appropriate, must appear on the permanent label:

U.S. ENVIRONMENTAL PROTECTION AGENCY

Certified to comply with 2014 particulate emission standards.

or

U.S. ENVIRONMENTAL PROTECTION AGENCY

Certified to comply with 2019 particulate emission standards.

(c) The label under paragraph (b) of this section must also contain the following 

statement on the permanent label:

“This appliance needs periodic inspection and repair for proper operation. Consult 

owner's manual for further information. It is against the law to operate this appliance in a 

manner inconsistent with operating instructions in the owner's manual.”

(d) Any label statement under paragraph (b) of this section constitutes a 

representation by the manufacturer as to any residential hydronic heater or forced-air 

furnace that bears it:

(1) That the certification of compliance was in effect at the time the residential 

hydronic heater or forced-air furnace left the possession of the manufacturer;

(2) That the manufacturer was, at the time the label was affixed, conducting a 

quality assurance program in conformity with the manufacturer’s quality assurance 

program; and

(3) That as to any residential hydronic heater or forced-air furnace individually

tested for emissions by the manufacturer under §60.5475(f), it met the applicable 

emission limit.
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(e)(1) If an affected residential hydronic heater or forced-air furnace is 

manufactured in the United States for export as provided in §60.5472(b)(1), the following 

statement must appear on the permanent label:

U.S. ENVIRONMENTAL PROTECTION AGENCY

Export appliance. May not be operated in the United States.

(2) If an affected residential hydronic heater or forced-air furnace is manufactured 

for use for research and development purposes as provided in §60.5472(b)(2), the 

following statement must appear on the permanent label:

U.S. ENVIRONMENTAL PROTECTION AGENCY

Not certified. Research Appliance. Not approved for sale.

(3) If an affected residential hydronic heater or forced-air furnace is a non woodburning hydronic heater or forced-air furnace exclusively as provided in §60.5472(b)(3) 

the following statement must appear on the permanent label:

U.S. ENVIRONMENTAL PROTECTION AGENCY

This appliance is not certified for wood burning. Use of any wood fuel is a violation of 

federal law.

(f) Owner’s Manual. 

(1) Each affected residential hydronic heater or forced-air furnace offered for sale 

by a commercial owner must be accompanied by an owner's manual that must contain the 

information listed in paragraph (f)(2) of this section (pertaining to installation), and 

paragraph (f)(3) of this section (pertaining to operation and maintenance). Such 

information must be adequate to enable consumers to achieve optimal emissions 

performance. Such information must be consistent with the operating instructions 
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provided by the manufacturer to the accredited test laboratory for operating the 

residential hydronic heater or forced-air furnace during certification testing, except for 

details of the certification test that would not be relevant to the ultimate purchaser. The 

commercial owner must also make current and historical owner’s manuals available on 

the company website.

(2) Installation information: Requirements for achieving proper draft.

(3) Operation and maintenance information:

(i) Fuel loading procedures, recommendations on fuel selection, and warnings on 

what fuels not to use, such as treated wood, colored paper, cardboard, solvents, trash and 

garbage.

(ii) Fire starting procedures

(iii) Proper use of air controls

(iv) Ash removal procedures

(v) Instructions for replacement of gaskets and other parts that are critical to the 

emissions performance of the unit and other maintenance and repair instructions

(vi) The following statement: “This wood heating appliance needs periodic 

inspection and repair for proper operation. It is against federal law to operate this wood 

heating appliance in a manner inconsistent with operating instructions in the manual.”

(4) Any manufacturer using the EPA model language contained in appendix I of 

this part to satisfy any requirement of this paragraph (f) will be considered to be in 

compliance with that requirement, provided that the particular model language is printed 

in full, with only such changes as are necessary to ensure accuracy for the particular 

model line.
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(i) Residential hydronic heaters and forced-air furnaces that are affected by this 

subpart but have been operated by a noncommercial owner are not subject to paragraph 

(f) of this section when offered for resale.

§60.5479 What records must I keep and what reports must I submit?

(a) Each manufacturer who holds a certificate of compliance pursuant to

§60.5475(a)(2) for a model line must maintain records containing the following 

information with respect to that model line.

(1) All documentation pertaining to the certification test used to obtain 

certification, including the full test report and raw data sheets, laboratory technician 

notes, calculations, and the test results for all test runs.

(2) Results of the quality assurance program inspections required pursuant to 

§60.5475(g).

(3) For emissions tests conducted pursuant to the quality assurance program 

required by §60.5475(g), all test reports, data sheets, laboratory technician notes, 

calculations, and test results for all test runs, the corrective actions taken, if any, and any

follow-up actions such as additional testing.

(b) Each accredited test laboratory must maintain records consisting of all 

documentation pertaining to each certification test and audit test, including the full test 

report and raw data sheets, laboratory technician notes, calculations, and the test results 

for all test runs. Each accredited test laboratory must submit initial and biennial 

proficiency test results to the Administrator.

(c) Each manufacturer must retain each residential hydronic heater and forced-air 

furnace upon which certification tests were performed and certification granted under 
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§60.5475(a)(2) at the manufacturer’s facility for as long as the model line is 

manufactured. Each heater or furnace must remain sealed and unaltered. Any such 

residential hydronic heater or forced-air furnace must be made available upon request to 

the Administrator for inspection and testing.

(d) Each manufacturer of an affected residential hydronic heater or forced-air 

furnace certified pursuant to §60.5475(a)(2) must submit a report to the Administrator 

every 2 years following issuance of a certificate of compliance for each model line. This 

report must include the sales for each model by state and certify that no changes in the 

design or manufacture of the model line have been made that require recertification 

pursuant to §60.5475(e).

(e)(1) Unless otherwise specified, all records required under this section must be 

maintained by the manufacturer, commercial owner of the affected residential hydronic 

heater or forced-air furnace, accredited test laboratory or certifying entity for a period of 

no less than 5 years.

(2) Unless otherwise specified, all reports to the Administrator required under this 

subpart must be made to: XXXX Compliance Program at xxxx.gov/yyyy.

(f) Within 60 days after the date of completing each performance test, each 

manufacturer or accredited test laboratory or certifying entity must submit performance 

test data electronically to the EPA’s Central Data Exchange (CDX) by using the 

Electronic Reporting Tool (ERT) (http://www.epa.gov/ttn/chief/ert/index.html). Only

data collected using test methods compatible with ERT are subject to this requirement to 

be submitted electronically to EPA’s CDX. Owners or operators who claim that some of 

the information being submitted for performance tests is confidential business 
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information (CBI) must submit a completed ERT file, including information claimed to 

be CBI on a compact disk or other commonly used electronic storage media (including, 

but not limited to, flash drives), to the EPA and the same ERT file, with the CBI omitted,

to the EPA via CDX as described earlier in this paragraph. The compact disk must be 

clearly marked as CBI and mailed to U.S. EPA/OAQPS/CORE CBI Office, Attention: 

WebFIRE Administrator, MD C404-02, 4930 Old Page Rd., Durham, NC 27703. 

Emission data and all information necessary to determine compliance, except sensitive 

engineering drawings and sensitive detailed material specifications, may not be claimed 

as CBI.

§60.5480 What activities are prohibited under this subpart?

(a) No person is permitted to operate an affected residential hydronic heater or 

forced-air furnace that does not have affixed to it a permanent label pursuant to 

§60.5478(b) or (c).

(b)(1) No commercial owner is permitted to advertise for sale, offer for sale, or 

sell an affected residential hydronic heater or forced-air furnace that does not have 

affixed to it a permanent label pursuant to §60.5478(b) or (e)(3).

(2) No commercial owner is permitted to advertise for sale, offer for sale, or sell 

an affected residential hydronic heater or forced-air furnace labeled under §60.5478(e)(1) 

except for export.

(c)(1) No commercial owner is permitted to advertise for sale, offer for sale, or 

sell an affected residential hydronic heater or forced-air furnace permanently labeled 

under §60.5478(b) or (e)(3) unless:
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(i) The affected appliance has been certified to comply with 2019 particulate 

emission standards. This prohibition does not apply to affected residential hydronic 

heaters or forced-air furnaces regulated under this subpart that have been previously

owned and operated by a noncommercial owner; and

(ii) The commercial owner provides any purchaser or transferee with an owner's 

manual that meets the requirements of §60.5478(f), a copy of the warranty and a moisture 

meter.

(2) A commercial owner other than a manufacturer complies with the 

requirements of paragraph (c)(1) of this section if the commercial owner:

(i) Receives the required documentation from the manufacturer or a previous 

commercial owner; and

(ii) Provides that documentation unaltered to any person to whom the residential 

hydronic heater or forced-air furnace that it covers is sold or transferred.

(d)(1) In any case in which the Administrator revokes a certificate of compliance 

either for the knowing submission of false or inaccurate information or other fraudulent 

acts, or based on a finding under §60.5475(e)(1)(ii) that the certification test was not 

valid, the Administrator may give notice of that revocation and the grounds for it to all 

commercial owners.

(2) On and after the date of receipt of the notice given under paragraph (d)(1) of 

this section, no commercial owner is permitted to sell any residential hydronic heater or 

forced-air furnace covered by the revoked certificate (other than to the manufacturer) 

unless the model line has been recertified in accordance with this subpart.
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(e) No person is permitted to install or operate an affected residential hydronic 

heater or forced-air furnace except in a manner consistent with the instructions on its 

permanent label and in the owner's manual pursuant to §60.5478(f), including only using 

fuels for which the unit is certified.

(f) No person is permitted to operate an affected residential hydronic heater or 

forced-air furnace that has been physically altered to exceed the tolerance limits of its 

certificate of compliance.

(g) No person is permitted to alter, deface, or remove any permanent label 

required to be affixed pursuant to §60.5478.

(h) No certifying entity is permitted to certify its own certification test report.

§60.5481 What Petition for Review procedures apply to me? 

(a) In any case where the Administrator:

(1) Denies an application under §60.5475(a)(2);

(2) Issues a notice of revocation of certification pursuant to §60.5475(e);

(3) Denies an application for laboratory accreditation pursuant to §60.5477; or

(4) Issues a notice of revocation of laboratory accreditation pursuant to §60.5477, 

the manufacturer or laboratory affected may submit to the EPA a request for review

under this section pursuant to the procedures specified in §60.539 within 30 days 

following receipt of the required notification of the action in question.

(b) In any case where the Administrator issues a notice of revocation pursuant to 

§60.5475(g), the manufacturer may submit to the EPA a Petition for Review request 

under this section with the time limits set out in §60.533(p)(4).

§60.5482 Who implements and enforces this subpart?
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(a) In delegating implementation and enforcement authority to a state under 

section 111(c) of the Clean Air Act, the authorities contained in paragraph (b) of this 

section must be retained by the Administrator and not transferred to a state.

(b) Authorities that must not be delegated to states:

(1) Section 60.5473, Definitions;

(2) Section 60.5475, Compliance and certification;

(3) Section 60.5476, Test methods and procedures; and

(4) Section 60.5477, Laboratory accreditation.

§60.5483 What parts of the General Provisions do not apply to me?

The following provisions of subpart A of part 60 do not apply to this subpart:

(a) Section 60.7;

(b) Section 60.8(a), (c), (d), (e), (f) and (g); and

(c) Section 60.15(d).

5. Part 60 is amended by adding subpart RRRR to read as follows:

Subpart RRRR – Standards of Performance for New Residential Masonry Heaters

Sec.

60.5484 Am I subject to this subpart?

60.5485 What definitions must I know?

60.5486 What standards and requirements must I meet and by when?

60.5487 What compliance and certification requirements must I meet and by when?

60.5488 What test methods and procedures must I use to determine compliance with the 

standards and requirements for certification?

60.5489 What procedures must I use for laboratory accreditation?
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60.5490 What requirements must I meet for permanent labels and owner's manuals?

60.5491 What records must I keep and what reports must I submit?

60.5492 What activities are prohibited under this subpart?

60.5493 What Petition for Review procedures apply to me?

60.5494 Who implements and enforces this subpart?

60.5495 What parts of the General Provisions do not apply to me?

Subpart RRRR – Standards of Performance for New Residential Masonry Heaters

§60.5484 Am I subject to this subpart?

(a) You are subject to this subpart if you operate, manufacture, sell, offer for sale, 

import for sale, distribute, offer to distribute, introduce, or deliver for introduction, into 

commerce in the United States, a residential masonry heater manufactured on or after 

[EFFECTIVE DATE OF FINAL RULE]. 

(b) Each affected masonry heater must comply with the provisions of this subpart 

unless exempted under paragraphs (b)(1) through (b)(3) of this section.

(1) Affected masonry heaters manufactured in the United States for export are 

exempt from the applicable emission limits of §60.5486 and the requirements of 

§60.5487.

(2) Affected masonry heaters used for research and development purposes that are 

never offered for sale or sold and that are not used to provide heat are exempt from the 

applicable emission limits of §60.5486 and the requirements of §60.5487. No more than 

six affected masonry heaters manufactured per model line may be exempted for this 

purpose.
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(3) Affected masonry heaters that do not burn wood or wood pellets (such as coalonly heaters that meet the definition in §60.5485 or corn-only heaters) are exempt from 

the applicable emission limits of §60.5486 and the requirements of §60.5487. 

(c) The following are not affected masonry heaters and are not subject to this 

subpart: 

(1) Residential wood heaters subject to subpart AAA of this part.

(2) Residential hydronic heaters and forced-air furnaces subject to subpart QQQQ 

of this part.

§60.5485 What definitions must I know?

As used in this subpart, all terms not defined herein have the same meaning given 

them in the Clean Air Act and subpart A of this part.

Accredited test laboratory means a test laboratory that is accredited for masonry

heater certification testing under §60.5489 or is an independent third party test laboratory

that is accredited by a nationally recognized accrediting entity under ISO-IEC Standard 

17025 to perform testing using the test methods specified in §60.5488 and approved by

the EPA for conducting certification tests under this subpart. 

At retail means the sale by a commercial owner of a residential masonry heater to 

the ultimate purchaser.

Certifying entity means an independent third party that is accredited by a 

nationally recognized accrediting entity under ISO-IEC Standard 17020 to perform 

certifications and inspections under ISO-IEC Guide 17065 and approved by the EPA for 

conducting certifications, inspections and audits under this subpart. 
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Coal-only heater means an enclosed, coal-burning appliance capable of space 

heating or domestic water heating which has all of the following characteristics:

(1) Installation instructions that state that the use of wood in the heater, except for 

coal ignition purposes, is prohibited by law; and

(2) The model is listed by a nationally recognized safety-testing laboratory for 

coal use only, except for coal ignition purposes.

Commercial owner means any person who owns or controls a residential masonry

heater in the course of the business of the manufacture, importation, distribution, or sale 

of the unit.

Manufactured means completed and ready for shipment (whether or not 

packaged) or installed in a residence in the case of custom-built masonry heaters for 

purposes of determining the date of manufacture.

Manufacturer means any person who constructs or imports into the United States 

a residential masonry heater.

Model line means all residential masonry heaters offered for sale by a single 

manufacturer that are similar in all material respects as defined in this section. 

Particulate matter (PM) means total particulate matter including PM10 and PM2.5.

Pellet fuel means refined and densified wood shaped into small pellets or 

briquettes that are uniform in size, shape, moisture, density and energy content. 

Representative affected masonry heater means an individual residential masonry

heater that is similar in all material respects as defined in this section to other residential

masonry heaters within the model line it represents.
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Residential masonry heater means a factory-built or site-built wood-burning 

device that has the following characteristics:

(1) The device has a core constructed primarily of manufacturer-built, supplied, or 

specified masonry materials (such as stone, cemented aggregate, clay, tile, or other noncombustible, non-metallic solid materials) that weighs at least 1700 pounds;

(2) The firebox effluent of the masonry heater travels horizontally and/or 

downward through one or more heat absorbing masonry duct(s) for a distance at least the 

length of the largest single internal firebox dimension before leaving the masonry heater. 

These parameters are determined as follows:

(i) Horizontal or downward travel distance is defined as the net horizontal and/or 

downward internal duct length, measured from the top of the uppermost firebox door 

opening(s) to the exit of the masonry heater as traveled by any effluent on a single 

pathway through duct channel(s) within the heater (or average of net internal duct lengths 

for multiple pathways of different lengths, if applicable). Net internal duct length is 

measured from the center of the internal side or top surface of a duct, horizontally or 

vertically to the center of the opposite side or the bottom surface of the same duct, and 

summed for multiple ducts or directions on a single pathway, if applicable. For duct 

channel(s) traversing horizontal angles of less than ninety degrees from vertical, only the 

net actual horizontal distance traveled is included in the total duct length; and

(ii) The largest single internal firebox dimensions is defined as the longest of 

either the length or the width of the firebox hearth and the height of the firebox, measured 

from the hearth to the top of the uppermost firebox door opening(s);
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(3) The device has one or more air-controlling doors for fuel-loading that are 

designed to be closed during the combustion of fuel loads, and that control the entry of 

combustion air (beyond simple spark arresting screens) to one or more inlets as 

prescribed by the masonry heater manufacturer; and

(4) The device is assembled in conformance with Underwriters Laboratories’ 

and/or manufacturer’s specifications for its assembly and, if the core is constructed with a 

substantial portion of materials not supplied by the manufacturer, is certified by a 

representative of the manufacturer to be substantially in conformance with those 

specifications.

Sale means the transfer of ownership or control, except that a transfer of control 

of an affected heater for research and development purposes within the scope of 

§60.5484(b)(2) is not a sale.

Seasoned wood means wood with a moisture content of 20 percent or less.

Similar in all material respects means that the construction materials, exhaust and 

inlet air system, and other design features are within the allowed tolerances for 

components identified in §60.533(k).

Valid certification test means a test that meets the following criteria:

(1) The Administrator was notified about the test in accordance with §60.5488(d) 

(2) The test was conducted by an accredited test laboratory as defined in this 

section;

(3) The test was conducted on a residential masonry heater similar in all material 

respects as defined in this section to other residential masonry heaters of the model line 

that is to be certified; and
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(4) The test was conducted in accordance with the test methods and procedures 

specified in §60.5488.

§60.5486 What standards and requirements must I meet and by when?

(a) Particulate Matter Standard. Unless exempted under §60.5484:

(1) On or after [EFFECTIVE DATE OF FINAL RULE], no person is permitted 

to manufacture and, on or after [6 MONTHS AFTER EFFECTIVE DATE OF FINAL 

RULE], no person is permitted to sell at retail a residential masonry heater unless the 

heater has been certified to meet the particulate matter emission limit in paragraph (b) of 

this section or the manufacturer is a small manufacturer as defined in paragraph (a)(2) of 

this section.

(2) On or after [5 YEARS AFTER EFFECTIVE DATE OF FINAL RULE], 

no small manufacturer is permitted to manufacture a residential masonry heater unless it 

has been certified to meet the particulate matter emission limit in paragraph (b) of this 

section. For the purposes of this subpart, a small manufacturer is defined as a 

manufacturer that constructs less than 15 residential masonry heaters per year. A small 

manufacturer may elect to comply with the emission limit in paragraph (b) of this section 

earlier than specified in this paragraph.

(b) Residential masonry heater particulate matter emission limit: 0.32 lb/million 

Btu (0.137 g/megajoule) heat output as determined by the test methods and procedures in 

§60.5488.

(c) Pellet Fuel Requirements. Operators of masonry heaters that are certified to 

burn pellet fuels may only burn pellets that have been produced under a licensing 
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agreement with the Pellet Fuel Institute or an equivalent organization approved by EPA. 

The pellet fuel must meet the following minimum requirements:

(1) Density: consistent hardness and energy content with a minimum density of 38 

pounds/cubic foot; 

(2) Dimensions: maximum length of 1.5 inches and diameter between 0.230 and 

0.285 inches; 

(3) Inorganic fines: less than or equal to 1 percent;

(4) Chlorides: less than or equal to 300 parts per million by weight; and 

(5) Ash content: no more than 2 percent.

(6) A quality assurance process licensed by the Pellet Fuel Institute or equivalent 

organization approved by the EPA.

(d) Prohibited Fuel Types. No person is permitted to burn any of the following 

materials in a residential masonry heater:

(1) Residential or commercial garbage;

(2) Lawn clippings or yard waste;

(3) Materials containing rubber, including tires;

(4) Materials containing plastic;

(5) Waste petroleum products, paints or paint thinners, or asphalt products;

(6) Materials containing asbestos;

(7) Construction or demolition debris;

(8) Paper products, cardboard, plywood, or particleboard. The prohibition against 

burning these materials does not prohibit the use of fire starters made from paper, 
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cardboard, saw dust, wax and similar substances for the purpose of starting a fire in an 

affected masonry heater; 

(9) Railroad ties or pressure treated wood;

(10) Manure or animal remains; or

(11) Salt water driftwood or other previously salt water saturated materials.

(e) Owner’s Manual. A person must not operate a residential masonry heater in a 

manner inconsistent with the owner’s manual. The owner’s manual must clearly specify

that operation in a manner inconsistent with the owner’s manual would violate the 

warranty.

§60.5487 What compliance and certification requirements must I meet and by when?

(a)(1) Certification Requirement. Each affected residential masonry heater must 

be certified to be in compliance with the applicable emission standards and other 

requirements of this subpart. For each model line manufactured or sold by a single entity, 

e.g., company or manufacturer, compliance with applicable emission standards of 

§60.5486(b) must be determined based on testing of representative affected appliances

within the model line. If one entity licenses a model line to another entity, each entity’s 

model line must be certified. If an entity changes the name of the entity or the name of 

the model, the manufacturer must apply for a new certification.

(2) The manufacturer of each model line must submit to the EPA the information 

required in paragraph (b) of this section and follow the certification procedure specified 

in §60.533(f) except that, for the purposes of this paragraph, the reference in §60.533(f) 

to the emission limits in §60.532 must be understood to refer to the emission limits in 

§60.5486(b) and the associated test methods are those specified in this subpart.
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(3) As an alternative to the certification process described in paragraph (a)(2) of 

this section, an applicant may choose to submit a computer model simulation program for 

review and certification by the certifying entity and subsequent review and approval by

the Administrator for use as a surrogate for emissions testing. The Administrator will 

post the certified model on the EPA Burnwise website.

(b) Waiver from Submitting Test Results. 

(1) An applicant for certification may apply for a potential waiver of the 

requirements to submit the results of a certification test pursuant to the certification 

procedures specified in §60.533(f) according to the procedure specified in §60.533(g)(1).

(2) Alternatively, an applicant may submit results using a validated computer 

model simulation program that demonstrates the masonry heater design meets the 

emission limit in §60.5486(b).

(c) Certification Period.

(1) Unless revoked sooner by the Administrator, a certificate of compliance will 

be valid for 5 years from the date of issuance.

(2) If the manufacturer qualifies as a small manufacturer as defined in 

§60.5486(a)(2) and the model was certified using the procedure defined in paragraph 

(a)(3) of this section, the certificate of compliance will be valid for the life of the model 

line unless it is revoked by the Administrator.

(d) Renewal of Certification. 

(1) Any manufacturer of an affected masonry heater may apply to the 

Administrator for potential renewal of a certificate of compliance by submitting the 

material specified in §60.533(b) and following the process specified in §60.533(f).
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(2) A certificate issued pursuant to paragraph (c)(1) of this section must be 

recertified or renewed every 5 years or the manufacture may choose to no longer 

manufacture or sell that model. If the manufacturer chooses to no longer manufacture or 

sell that model, then the manufacturer must submit a statement to EPA for that model. A 

manufacturer may apply to the Administrator for potential renewal of their certificate by

submitting certification information in accordance with §60.533(b) or by affirming in 

writing that the wood heater has been subject to no changes that would impact emissions 

and request a potential waiver from certification testing.

(3) If the Administrator waives certification testing under paragraph (c)(2) of this 

section, the Administrator will give written notice to the manufacturer setting forth the 

basis for the determination and issue a certification.

(4) If the Administrator denies the request, the Administrator will give written 

notice to the manufacturer setting forth the basis for the determination.

(e) Recertification. 

(1) The procedure specified in §60.533(k) must be used to determine when a 

model line must be recertified.

(2) If the manufacturer qualifies as a small manufacturer as defined in 

§60.5486(a)(2) and the model line was certified using the procedure defined in paragraph 

(a)(3) of this section, the recertification provisions of paragraph (e)(1) of this section do 

not apply. 

(f) Criteria for Revocation of Certification.

(1) The Administrator may revoke certification of a model line if it is determined

that the residential masonry heaters produced in that model line do not comply with the 
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requirements of this subpart. Such a determination will be based on all available 

evidence, including but not limited to:

(i) Test data from retesting of the original unit on which the certification was 

conducted or a similar unit;

(ii) A finding that the certification test or model simulation was not valid; (iii) A 

finding that the labeling of the residential masonry heater model line or the associated 

owner’s manual or marketing information does not comply with the requirements of 

§60.5490;

(iii) Failure by the manufacturer to comply with the reporting and recordkeeping 

requirements of §60.5491;

(iv) Physical examination showing that an inspected production unit is not similar 

in all material respects as defined in this subpart to the representative affected masonry

heater submitted for testing; or

(v) Failure of the manufacturer to conduct a quality assurance program in 

conformity with paragraph (f) of this section.

(2) Revocation of certification under this paragraph will not take effect until the 

manufacturer concerned has been given written notice by the Administrator setting forth 

the basis for the proposed determination and an opportunity to request a Petition for 

Review under §60.5493.

(g) Quality Assurance Program. For each certified model line, except for any 

model line at small manufacturers as defined in §60.5486(a)(2) and where the model line 

was certified using the procedure defined in paragraph (a)(3) of this section, the 
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manufacturer must conduct a quality assurance program according to the requirements of 

§60.533(m).

(h) EPA Compliance Audit Testing. The Administrator may conduct compliance 

audit testing according to the requirements of §60.533(n). For the purposes of this 

paragraph, references in §60.533(p) to §§60.532 through 60.535 must be understood to 

refer to the comparable paragraphs in §§60.5486 through 60.5489, respectively. The 

requirements of this paragraph do not apply to small manufacturers as defined in 

§60.5486(a)(2) and where the model line was certified using the procedure defined in 

paragraph (a)(3) of this section.

§60.5488 What test methods and procedures must I use to determine compliance with the 

standards and requirements for certification?

Test methods and procedures specified in this section or in appendix A of this 

part, except as provided under §60.8(b), must be used to determine compliance with the 

standards and requirements for certification under §§60.5486 and 60.5487 as follows :

(a) ASTM E2817-11, Standard Test Method for Test Fueling Masonry Heaters, 

must be used to measure the heat output (million Btu/hr) of residential masonry heaters.

(b) ASTM E2515-10 must be used in conjunction with ASTM E2817-11 to 

measure the particulate emission rate (lb/million BTU heat output) of residential masonry

heaters.

(c)(1) ASTM WK26558, New Specification for Calculation Method for Custom 

Designed, Site Built Masonry Heaters may be used as an alternative to certification 

testing as specified in paragraphs (a), (b) and (d) of this section.
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(2) If the Administrator approves an alternative computer model simulation 

program pursuant to §60.5487(a)(3), the approved simulation program also may be used 

as an alternative to certification testing as specified in paragraphs (a) and (b) of this 

section.

(d) Method 10 in appendix A-4 of this part must be used to measure CO 

emissions of residential masonry heaters.

(e) The manufacturer of an affected masonry heater must notify the Administrator 

of the date that certification testing is to begin, by email, to XXXX Compliance Program 

at xxxx.gov/yyyy. This notice must be received at least 30 days before the start of testing. 

The notification of testing must include the manufacturer’s name and address, the 

accredited test laboratory’s name and address, certifying entity name, the model name 

and number (or, if unavailable, some other way to distinguish between models), and the 

dates of testing.

(f) The accredited test laboratory must allow the manufacturer, the EPA and 

delegated states to observe certification testing. However, manufacturers must not 

involve themselves in the conduct of the test after the pretest burn (as defined by ASTM 

E2817-11) has begun. Communications between the manufacturer and laboratory or 

certifying entity personnel regarding operation of the masonry heater must be limited to 

written communications transmitted prior to the first pretest burn of the certification 

series. Written communications between the manufacturer and laboratory personnel may

be exchanged during the certification test only if deviations from the test procedures are 

observed that constitute improper conduct of the test. All communications must be 

included in the test documentation required to be submitted pursuant to §60.533(b)(3) 
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and must be consistent with instructions provided in the owner's manual required under 

§60.5490(g), except to the extent that they address details of the certification tests that 

would not be relevant to owners.

§60.5489 What procedures must I use for laboratory accreditation?

The accreditation procedure specified in §60.535 must be used to certify test 

laboratories under this subpart.

§60.5490 What requirements must I meet for permanent labels and owner's manuals?

(a) Permanent Label Requirements.

(1) Each affected masonry heater manufactured on or after the date the applicable 

standards come into effect as specified in §60.5486, must have a permanent label affixed 

to it that meets the requirements of this section.

(2) The permanent label must contain the following information:

(i) Month and year of manufacture of the individual unit;

(ii) Model name or number; and

(iii) Serial number.

(3) The permanent label must:

(i) Be affixed in a readily visible or accessible location in such a manner that it 

can be easily viewed before and after the appliance is installed;

(ii) Be at least 8.9 cm long and 5.1 cm wide (3 1/2 inches long and 2 inches wide);

(iii) Be made of a material expected to last the lifetime of the residential masonry

heater;

(iv) Present required information in a manner so that it is likely to remain legible 

for the lifetime of the residential masonry heater; and
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(v) Be affixed in such a manner that it cannot be removed without damage to the 

label.

(4) The permanent label may be combined with any other label, as long as the 

required information is displayed, the integrity of the permanent label is not 

compromised, and the requirements of §60.5490(3) are still met.

(b)(1) If the residential masonry heater belongs to a model line certified under 

§60.5487, and it has been found to meet the applicable emission limits or tolerances 

through quality assurance testing, the following statement must appear on the permanent 

label:

U.S. ENVIRONMENTAL PROTECTION AGENCY

Certified to comply with 2014 particulate emissions standards.

(2) If the masonry heater belongs to a model line owned by a manufacturer that 

qualifies for the small volume manufacturer delay as specified in §60.5486(a)(2), the 

following statement must appear on the permanent label:

U.S. ENVIRONMENTAL PROTECTION AGENCY

This masonry heater was produced by a small volume manufacturer that manufactures or 

exports to the United States fewer than 15 masonry heaters per year. This appliance 

cannot be sold after [5 YEARS AFTER EFFECTIVE DATE OF FINAL RULE].

(c) The label under paragraph (b) of this section must also contain the following 

statement on the permanent label: “This appliance needs periodic inspection and repair 

for proper operation. Consult owner’s manual for further information. It is against the law 

to operate this appliance in a manner inconsistent with operating instructions in the 

owner’s manual.”
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(d) Any label statement under paragraph (b) of this section constitutes a 

representation by the manufacturer as to any residential masonry heater that bears it:

(1) That the certification was in effect at the time the residential masonry heater 

left the possession of the manufacturer;

(2) That the manufacturer was, at the time the label was affixed, conducting a 

quality assurance program in conformity with the manufacturer’s quality assurance 

program; and

(3) That as to any residential masonry heater individually tested for emissions by

the manufacturer under §60.5487(f), it met the applicable emission limit.

(e)(1) If an affected masonry heater is manufactured in the United States for 

export as provide in §60.5484(b)(1), the following statement must appear on the 

permanent label:

U.S. ENVIRONMENTAL PROTECTION AGENCY

Export unit. May not be operated in the United States.

(2) If an affected masonry heater is manufactured for research and development 

purposes as provided in §60.5484(b)(2), the following statement must appear on the 

permanent label:

U.S. ENVIRONMENTAL PROTECTION AGENCY

Not certified. Research unit. Not approved for sale.

(3) If an affected masonry heater is a non wood-burning masonry heater 

exclusively as provided §60.5484(b)(3) the following statement must appear on the 

permanent label:

U.S. ENVIRONMENTAL PROTECTION AGENCY
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This appliance is not certified for wood burning. Use of any wood fuel is a violation of 

federal law.

(f) Owner’s Manual.

(1) Each affected masonry heater offered for sale by a commercial owner must be 

accompanied by an owner's manual that must contain the information listed in paragraph 

(f)(2) of this section (pertaining to installation), and paragraph (f)(3) of this section 

(pertaining to operation and maintenance). Such information must be adequate to enable 

consumers to achieve optimal emissions performance. Such information must be 

consistent with the operating instructions provided by the manufacturer to the accredited 

test laboratory for operating the residential masonry heater, except for details of the 

certification test that would not be relevant to the ultimate purchaser. The commercial 

owner must also make current and historical owner’s manuals available on the company 

website.

(2) Installation information: Requirements for achieving proper draft.

(3) Operation and maintenance information:

(i) Fuel loading procedures, recommendations on fuel selection, and warnings on 

what fuels not to use, such as treated wood, colored paper, cardboard, solvents, trash and 

garbage.

(ii) Fire starting procedures

(iii) Proper use of air controls

(iv) Ash removal procedures

(v) Instructions for replacement of gasket and other parts that are critical to the 

emissions performance of the unit and other maintenance and repair instructions
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(vi) The following statement: “This wood heating appliance needs periodic 

inspection and repair for proper operation. It is against federal law to operate this wood 

heating appliance in a manner inconsistent with operating instructions in the manual.”

(4) Any manufacturer using the EPA model language contained in appendix I of 

this part to satisfy any requirement of this paragraph (f) will be considered to be in 

compliance with that requirement, provided that the particular model language is printed 

in full, with only such changes as are necessary to ensure accuracy for the particular 

model line.

(g) Residential masonry heaters that are affected by this subpart but have been 

operated by a noncommercial owner are not subject to paragraph (f) of this section when 

offered for resale.

§60.5491 What records must I keep and what reports must I submit?

(a) Each manufacturer who holds a certificate of compliance pursuant to 

§60.5487(a)(2) for a model line must maintain records containing the information 

required by this paragraph (a) with respect to that model line.

(1) All documentation pertaining to the certification test or computer simulation 

used to obtain certification. 

(i) For certification tests, this includes the full test report and raw data sheets, 

laboratory technician notes, calculations, and the test results for all test runs.

(ii) For computer simulations, this includes all data input into the simulation 

program and all computer-generated output.

(2) Results of the quality assurance program inspections required pursuant to 

§60.5487(f).
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(3) For emissions tests conducted pursuant to the quality assurance program 

required by §60.5487(f), all test reports, data sheets, laboratory technician notes, 

calculations, and test results for all test runs, the remedial actions taken, if any, and any

follow-up actions such as additional testing.

(4) If a masonry heater manufacturer qualifies as a small volume manufacturer as 

specified in §60.5486(a)(2) and elects to defer compliance as allowed by that paragraph, 

records of the number of masonry heaters produced or constructed per year during the 

deferral period.

(b) Each accredited test laboratory must maintain records consisting of all 

documentation pertaining to each certification test, audit test, or computer simulation, 

including the full test report and raw data sheets, laboratory technician notes, 

calculations, and the test results for all test runs. Each accredited test laboratory must 

submit initial and biennial proficiency test results to the Administrator.

(c) Each manufacturer must retain each residential masonry heater upon which 

certification tests were performed and certification granted pursuant to §60.5487(a)(2) at 

the manufacturer’s facility for as long as the model line is manufactured. Each masonry

heater must remain sealed and unaltered. Any such residential masonry heater must be 

made available upon request to the Administrator for inspection and testing.

(d)(1) Each manufacturer of an affected masonry heater certified pursuant to 

§60.5487 must submit a report to the Administrator every 2 years following issuance of a 

certificate of compliance for each model line. This report must include the sales for each 

model by state and certify that no changes in the design or manufacture of the model line 

have been made that require recertification pursuant to §60.5487(d).
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(2) If the manufacturer qualifies as a small manufacturer as defined in 

§60.5486(b)(2) and the model line was certified using the procedure defined in paragraph 

(a)(3) of this section, the reporting provision of paragraph (d)(1) of this section does not 

apply. 

(e)(1) Unless otherwise specified, all records required under this section must be

maintained by the manufacturer, commercial owner of the affected masonry heater, 

accredited test laboratory or certifying entity for a period of no less than 5 years.

(2) Unless otherwise specified, all reports to the Administrator required under this 

subpart must be made to: XXXX Compliance Program at xxxx.gov/yyyy.

(f) Within 60 days after the date of completing each performance test, each 

manufacturer or accredited test laboratory or certifying entity must submit performance 

test data, except opacity data, electronically to the EPA’s Central Data Exchange (CDX) 

by using the Electronic Reporting Tool (ERT) 

(http://www.epa.gov/ttn/chief/ert/index.html). Only data collected using test methods 

compatible with ERT are subject to this requirement to be submitted electronically to the 

EPA’s CDX. Owners or operators who claim that some of the information being 

submitted for performance tests is confidential business information (CBI) must submit a 

completed ERT file, including information claimed to be CBI, on a compact disk or other 

commonly used electronic storage media (including, but not limited to, flash drives), to 

the EPA, and the same ERT file, with the CBI omitted, to the EPA via CDX as described 

earlier in this paragraph. The compact disk must be clearly marked as CBI and mailed to 

U.S. EPA/OAQPS/CORE CBI Office, Attention: WebFIRE Administrator, MD C404-02, 

4930 Old Page Rd., Durham, NC 27703. Emission data and all information necessary to 
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determine compliance, except sensitive engineering drawings and sensitive detailed 

material specifications, may not be claimed as CBI. 

§60.5492 What activities are prohibited under this subpart?

(a) No person is permitted to operate an affected masonry heater manufactured 

after [EFFECTIVE DATE OF FINAL RULE] or sold at retail after [6 MONTHS 

AFTER EFFECTIVE DATE OF FINAL RULE] that does not have affixed to it a 

permanent label pursuant to §60.5490.

(b)(1) No manufacturer or commercial owner is permitted to advertise for sale, 

offer for sale, or sell an affected masonry heater manufactured after [EFFECTIVE 

DATE OF FINAL RULE] or sold at retail after [6 MONTHS AFTER EFFECTIVE 

DATE OF FINAL RULE] that does not have affixed to it a permanent label pursuant to 

§60.5490. 

(2) No manufacturer or commercial owner is permitted to advertise for sale, offer 

for sale, or sell an affected masonry heater manufactured after [EFFECTIVE DATE OF 

FINAL RULE] or sold at retail after [6 MONTHS AFTER EFFECTIVE DATE OF 

FINAL RULE] labeled under §60.5490(d)(1) except for export.

(c)(1) No commercial owner is permitted to advertise for sale, offer for sale or sell 

an affected masonry heater permanently labeled under §60.5490(b) unless:

(i) The affected appliance regulated under this subpart was previously owned and 

operated by a noncommercial owner; 

(ii) The commercial owner provides any purchaser or transferee with an owner's 

manual that meets the requirements of §60.5490(g), a copy of the warranty and a 

moisture meter.
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(2) A commercial owner other than a manufacturer complies with the 

requirements of paragraph (c) of this section if the commercial owner:

(i) Receives the required documentation from the manufacturer or a previous 

commercial owner; and

(ii) Provides that documentation unaltered to any person to whom the residential 

masonry heater that it covers is sold or transferred.

(d)(1) In any case in which the Administrator revokes a certificate of compliance 

either for the knowing submission of false or inaccurate information or other fraudulent 

acts, or based on a finding under §60.5487(e)(1)(ii) that the certification test was not 

valid, the Administrator may give notice of that revocation and the grounds for it to all 

commercial owners.

(2) On and after the date of receipt of the notice given under paragraph (d)(1) of 

this section, no commercial owner is permitted to sell any residential masonry heater 

covered by the revoked certificate (other than to the manufacturer) unless the model line 

has been recertified in accordance with this subpart.

(e) No person is permitted to install or operate an affected masonry heater except 

in a manner consistent with the instructions on its permanent label and in the owner's 

manual pursuant to §60.5490(g), including only using fuels for which the unit is certified.

(f) No person is permitted to operate an affected masonry heater that has been 

physically altered to exceed the tolerance limits of its certificate of compliance.

(g) No person is permitted to alter, deface, or remove any permanent label 

required to be affixed pursuant to §60.5490.

(h) No certifying entity is permitted to certify its own certification test report.
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§60.5493 What Petition for Review procedures apply to me?

(a) In any case where the Administrator:

(1) Denies an application under §60.5487(a)(2);

(2) Issues a notice of revocation of certification under §60.5487(e);

(3) Denies an application for laboratory accreditation pursuant to §60.5489; or

(4) Issues a notice of revocation of laboratory accreditation pursuant to §60.5489, 

the manufacturer or laboratory affected may submit to the EPA a Petition for Review

request under this section pursuant to the procedures specified in §60.593 within 30 days 

following receipt of the required notification of the action in question.

(b) In any case where the Administrator issues a notice of revocation under 

§60.5487(e), the manufacturer may submit to the EPA a Petition for Review request 

under this section pursuant to the procedures specified in §60.5493 with the time limits 

set out in §60.533(p)(4).

§60.5494 Who implements and enforces this subpart?

(a) In delegating implementation and enforcement authority to a state under 

section 111(c) of the Clean Air Act, the authorities contained in paragraph (b) of this 

section must be retained by the Administrator and not transferred to a state.

(b) Authorities that must not be delegated to states:

(1) Section 60.5473, Definitions;

(2) Section 60.5475, Compliance and certification;

(3) Section 60.5476, Test methods and procedures; and

(4) Section 60.5477, Laboratory accreditation.

§60.5495 What parts of the General Provisions do not apply to me?
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The following provisions of subpart A of part 60 do not apply to this subpart:

(a) Section 60.7;

(b) Section 60.8(a), (c), (d), (e), and (f); and

(c) Section 60.15(d).

6. Part 60 Appendix A-8 is amended by adding Method 28R to follow Method 

28A to read as follows:

Test Method 28R for Certification and Auditing of Wood Heaters

1.0 Scope and Application

1.1 This test method applies to certification and auditing of wood-fired room 

heaters and fireplace inserts.

1.2 The test method covers the fueling and operating protocol for measuring 

particulate emissions, as well as determining burn rates, heat output and efficiency.

1.3 Particulate emissions are measured by the dilution tunnel method as specified 

in ASTM E2515-10 Standard Test Method for Determination of Particulate Matter 

Emissions Collected in a Dilution Tunnel.

2.0 Procedures

2.1 This method incorporates the provisions of ASTM E2780-10 except as 

follows:

2.1.1 The burn rate categories, low burn rate requirement, and weightings in 

Method 28 shall be used.

2.1.2 The startup procedures shall be the same as in Method 28.

2.1.3 The equation for converting the emission test values between the EPA 

Reference Method 5G “Determination of Particulate Emissions From Wood Heaters 
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From a Dilution Tunnel Sampling Location” and EPA Reference Method 5H 

“Determination of Particulate Emissions From Wood Heaters From a Stack Location” 

shall be the same as in Method 28.

2.1.4 Manufacturers shall not specify a smaller volume of the firebox for testing 

than the full usable firebox.

2.1.5 The test fuel moisture content, fuel load, and coal bed depth shall be as 

follows:

(a) The fuel load dry-basis moisture content shall be within a range of 22.5 

percent +/- 1 percent;

(b) The fuel load weight shall be 7 lb/ft3+/- 1 percent (or 7 lb +/-0.07 lb) of the 

fuel load weight, calculated in accordance with Method 28; and

(c) The range for the test-initiation coal-bed weight shall be 22 percent +/- 1 

percent of the fuel load weight.

7. Part 60 Appendix A-8 is amended by adding Method 28 WHH to follow 

Method 28A to read as follows:

Test Method 28 WHH for Measurement of Particulate Emissions and Heating 

Efficiency of Wood-Fired Hydronic Heating Appliances

1.0 Scope and Application

1.1 This test method applies to wood-fired hydronic heating appliances. The units 

typically transfer heat through circulation of a liquid heat exchange media such as water 

or a water-antifreeze mixture.

1.2 The test method measures particulate emissions and delivered heating 

efficiency at specified heat output rates based on the appliance’s rated heating capacity.
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1.3 Particulate emissions are measured by the dilution tunnel method as specified 

in ASTM E2515-10 Standard Test Method for Determination of Particulate Matter 

Emissions Collected in a Dilution Tunnel. Delivered Efficiency is measured by

determining the heat output through measurement of the flow rate and temperature 

change of water circulated through a heat exchanger external to the appliance and 

determining the input from the mass of dry wood fuel and its higher heating value. 

Delivered efficiency does not attempt to account for pipeline loss.

1.4 Products covered by this test method include both pressurized and nonpressurized heating appliances intended to be fired with wood. These products are woodfired hydronic heating appliances that the manufacturer specifies for indoor or outdoor 

installation. They are often connected to a heat exchanger by insulated pipes and 

normally include a pump to circulate heated liquid. They are used to heat structures such 

as homes, barns and greenhouses and can heat domestic hot water, spas or swimming 

pools.

1.5 Distinguishing features of products covered by this standard include:

1.5.1 Manufacturer specifies for indoor or outdoor installation.

1.5.2 A firebox with an access door for hand loading of fuel.

1.5.3 Typically an aquastat that controls combustion air supply to maintain the 

liquid in the appliance within a predetermined temperature range provided sufficient fuel 

is available in the firebox.

1.5.4 A chimney or vent that exhausts combustion products from the appliance.

1.6 The values stated are to be regarded as the standard whether in I-P or SI units. 

The values given in parentheses are for information only.
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2.0 Summary of Method and References

2.1 Particulate matter emissions are measured from a wood-fired hydronic heating 

appliance burning a prepared test fuel crib in a test facility maintained at a set of 

prescribed conditions. Procedures for determining burn rates, and particulate emissions 

rates and for reducing data are provided.

2.2 Referenced Documents

2.2.1 EPA Standards

2.2.1.1 Method 28 Certification and Auditing of Wood Heaters

2.2.2 Other Standards

2.2.2.1 ASTM E2515-10 Standard Test Method for Determination of Particulate 

Matter Emissions Collected in a Dilution Tunnel.

2.2.2.2 CAN/CSA-B415.1-2010 Performance Testing of Solid-Fuel-Burning 

Heating Appliances.

3.0 Terminology

3.1 Definitions

3.1.1 Hydronic Heating – A heating system in which a heat source supplies 

energy to a liquid heat exchange media such as water that is circulated to a heating load 

and returned to the heat source through pipes.

3.1.2 Aquastat – A control device that opens or closes a circuit to control the rate 

of fuel consumption in response to the temperature of the heating media in the heating 

appliance.

3.1.3 Delivered Efficiency – The percentage of heat available in a test fuel charge 

that is delivered to a simulated heating load as specified in this test method. 
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3.1.4 Manufacturer’s Rated Heat Output Capacity −The value in BTU/hr (MJ/hr) 

that the manufacturer specifies that a particular model of hydronic heating appliance is 

capable of supplying at its design capacity as verified by testing, in accordance with 

Section 13.

3.1.5 Burn rate − The rate at which test fuel is consumed in an appliance. 

Measured in pounds (lbs) of wood (dry basis) per hour (kg/hr).

3.1.6 Firebox − The chamber in the appliance in which the test fuel charge is 

placed and combusted.

3.1.7 Test fuel charge − The collection of Test Fuel layers placed in the appliance 

at the start of the emission test run.

3.1.8 Test Fuel Layer – Horizontal arrangement of Test Fuel Units.

3.1.9 Test Fuel Unit − One or more Test Fuel Pieces with 3⁄4 inch (19 mm) spacers 

attached to the bottom and to one side. If composed of multiple Test Fuel Pieces, the 

bottom spacer may be one continuous piece.

3.1.10 Test Fuel Piece − A single 4 x 4 (4 ± 0.25 inches by 4 ± 0.25 inches)[100 ± 

6 mm by 100 ± 6 mm] white or red oak wood piece cut to the length required.

3.1.11 Test Run – An individual emission test that encompasses the time required 

to consume the mass of the test fuel charge.

3.1.12 Overall Efficiency (SLM) – The efficiency for each test run as determined 

using the CSA B415.1-2010 Stack Loss Method. 

3.1.13 Thermopile - A device consisting of a number of thermocouples connected 

in series, used for measuring differential temperature.

4.0 Summary of Test Method
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4.1 Dilution Tunnel. Emissions are determined using the “dilution tunnel” method 

specified in ASTM E2515 Standard Test Method for Determination of Particulate Matter 

Emissions Collected in a Dilution Tunnel. The flow rate in the dilution tunnel is 

maintained at a constant level throughout the test cycle and accurately measured. 

Samples of the dilution tunnel flow stream are extracted at a constant flow rate and drawn 

through high efficiency filters. The filters are dried and weighed before and after the test 

to determine the emissions catch and this value is multiplied by the ratio of tunnel flow to 

filter flow to determine the total particulate emissions produced in the test cycle.

4.2 Efficiency. The efficiency test procedure takes advantage of the fact that this 

type of appliance delivers heat through circulation of the heated liquid (water) from the 

appliance to a remote heat exchanger and back to the appliance. Measurements of the 

water temperature difference as it enters and exits the heat exchanger along with the 

measured flow rate allow for an accurate determination of the useful heat output of the 

appliance. The input is determined by weight of the test fuel charge, adjusted for moisture 

content, multiplied by the Higher Heating Value. Additional measurements of the 

appliance weight and temperature at the beginning and end of a test cycle are used to 

correct for heat stored in the appliance. Overall Efficiency (SLM) is determined using the 

CSA B415.1-2010 stack loss method for data quality assurance purposes.

4.3 Operation. Appliance operation is conducted on a hot-to-hot test cycle 

meaning that the appliance is brought to operating temperature and a coal bed is 

established prior to the addition of the test fuel charge and measurements are made for 

each test fuel charge cycle. The measurements are made under constant heat draw 

conditions within predetermined ranges. No attempt is made to modulate the heat demand 
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to simulate an indoor thermostat cycling on and off in response to changes in the indoor 

environment. Four test categories are used. These are:

4.3.1 Category I: A heat output of 15 percent or less of Manufacturer’s Rated 

Heat Output Capacity.

4.3.2 Category II: A heat output of 16 percent to 24 percent of Manufacturer’s 

Rated Heat Output Capacity.

4.3.3 Category III: A heat output of 25 percent to 50 percent of Manufacturer’s 

Rated Heat Output Capacity.

4.3.4 Category IV: Manufacturer’s Rated Heat Output Capacity.

5.0 Significance and Use

5.1 The measurement of particulate matter emission rates is an important test 

method widely used in the practice of air pollution control.

5.1.1 These measurements, when approved by state or federal agencies, are often 

required for the purpose of determining compliance with regulations and statutes.

5.1.2 The measurements made before and after design modifications are necessary

to demonstrate the effectiveness of design changes in reducing emissions and make this 

standard an important tool in manufacturers’ research and development programs.

5.2 Measurement of heating efficiency provides a uniform basis for comparison of 

product performance that is useful to the consumer. It is also required to relate emissions 

produced to the useful heat production.

5.3 This is a laboratory method and is not intended to be fully representative of all 

actual field use. It is recognized that users of hand-fired, wood-burning equipment have a 

great deal of influence over the performance of any wood-burning appliance. Some 
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compromises in realism have been made in the interest of providing a reliable and 

repeatable test method.

6.0 Test Equipment

6.1 Scale. A platform scale capable of weighing the appliance under test and 

associated parts and accessories when completely filled with water to an accuracy of ±1.0 

pound (±0.5 kg).

6.2 Heat exchanger. A water-to-water heat exchanger capable of dissipating the 

expected heat output from the system under test.

6.3 Water Temperature Difference Measurement. A Type –T ‘special limits’ 

thermopile with a minimum of 5 pairs of junctions shall be used to measure the 

temperature difference in water entering and leaving the heat exchanger. The temperature 

difference measurement uncertainty of this type of thermopile is equal to or less than ± 

0.50 oF (± 0. 25 oC). Other temperature measurement methods may be used if the 

temperature difference measurement uncertainty is equal to or less than. ± 0.50 oF (± 0. 

25 oC). 

6.4 Water flow meter. A water flow meter shall be installed in the inlet to the load 

side of the heat exchanger. The flow meter shall have an accuracy of ± 1 percent of 

measured flow. 

6.4.1 Optional - Appliance side water flow meter. A water flow meter with an

accuracy of ± 1 percent of the flow rate is recommended to monitor supply side water 

flow rate.

6.5 Optional Recirculation Pump. Circulating pump used during test to prevent 

stratification of liquid being heated.
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6.6 Water Temperature Measurement – Thermocouples or other temperature 

sensors to measure the water temperature at the inlet and outlet of the load side of the 

heat exchanger. Must meet the calibration requirements specified in 10.1.

6.7 Wood Moisture Meter - Calibrated electrical resistance meter capable of 

measuring test fuel moisture to within 1 percent moisture content. Must meet the 

calibration requirements specified in 10.4.

6.8 Flue Gas Temperature Measurement - Must meet the requirements of CSA 

B415.1-2010, Clause 6.2.2.

6.9 Test Room Temperature Measurement - Must meet the requirements of CSA 

B415.1-2010, Clause 6.2.1.

6.10 Flue Gas Composition Measurement - Must meet the requirements of CSA 

B415.1-2010, Clauses 6.3.1 through 6.3.3.

7.0 Safety

7.1 These tests involve combustion of wood fuel and substantial release of heat 

and products of combustion. The heating system also produces large quantities of very

hot water and the potential for steam production and system pressurization. Appropriate 

precautions must be taken to protect personnel from burn hazards and respiration of 

products of combustion.

8.0 Sampling, Test Specimens and Test Appliances

8.1 Test specimens shall be supplied as complete appliances including all controls 

and accessories necessary for installation in the test facility. A full set of specifications 

and design and assembly drawings shall be provided when the product is to be placed 
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under certification of a third-party agency. The manufacturer’s written installation and 

operating instructions are to be used as a guide in the set-up and testing of the appliance.

9.0 Preparation of Test Equipment

9.1 The appliance is to be placed on a scale capable of weighing the appliance 

fully loaded with a resolution of ± 1.0 lb (0.5 kg).

9.2 The appliance shall be fitted with the type of chimney recommended or 

provided by the manufacturer and extending to 15 ±0.5 feet (4.6 ± 0.15 m) from the 

upper surface of the scale. If no flue or chimney system is recommended or provided by 

the manufacturer, connect the appliance to a flue of a diameter equal to the flue outlet of 

the appliance. The flue section from the appliance flue collar to 8 ± 0.5 feet above the 

scale shall be single wall stove pipe and the remainder of the flue shall be double wall 

insulated class A chimney.

9.3 Optional Equipment Use

9.3.1 A recirculation pump may be installed between connections at the top and 

bottom of the appliance to minimize thermal stratification if specified by the 

manufacturer. The pump shall not be installed in such a way as to change or affect the 

flow rate between the appliance and the heat exchanger.

9.3.2 If the manufacturer specifies that a thermal control valve or other device be 

installed and set to control the return water temperature to a specific set point, the valve 

or other device shall be installed and set per the manufacturer’s written instructions.

9.4 Prior to filling the tank, weigh and record the appliance mass.

9.5 Heat Exchanger
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9.5.1 Plumb the unit to a water-to-water heat exchanger with sufficient capacity to 

draw off heat at the maximum rate anticipated. Route hoses, electrical cables, and 

instrument wires in a manner that does not influence the weighing accuracy of the scale 

as indicated by placing dead weights on the platform and verifying the scale’s accuracy.

9.5.2 Locate thermocouples to measure the water temperature at the inlet and 

outlet of the load side of the heat exchanger.

9.5.3 Install a thermopile meeting the requirements of 6.3 to measure the water 

temperature difference between the inlet and outlet of the load side of the heat exchanger.

9.5.4 Install a calibrated water flow meter in the heat exchanger load side supply 

line. The water flow meter is to be installed on the cooling water inlet side of the heat 

exchanger so that it will operate at the temperature at which it is calibrated.

9.5.5 Place the heat exchanger in a box with 2 in. (50 mm) of expanded 

polystyrene (EPS) foam insulation surrounding it to minimize heat losses from the heat 

exchanger. 

9.5.6 The reported efficiency and heat output rate shall be based on measurements 

made on the load side of the heat exchanger.

9.5.7 Temperature instrumentation per 6.6 shall be installed in the appliance outlet 

and return lines. The average of the outlet and return water temperature on the supply 

side of the system shall be considered the average appliance temperature for calculation 

of heat storage in the appliance (TFavg and TIavg). Installation of a water flow meter in the 

supply side of the system is optional. 
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9.6 Fill the system with water. Determine the total weight of the water in the 

appliance when the water is circulating. Verify that the scale indicates a stable weight 

under operating conditions. Make sure air is purged properly.

10.0 Calibration and Standardization

10.1 Water Temperature Sensors. Temperature measuring equipment shall be 

calibrated before initial use and at least semi-annually thereafter. Calibrations shall be in 

compliance with National Institute of Standards and Technology (NIST) Monograph 175, 

Standard Limits of Error.10.2 Heat Exchanger Load Side Water Flow Meter. 

10.2.1 The heat exchanger load side water flow meter shall be calibrated within 

the flow range used for the test run using NIST Traceable methods. Verify the calibration 

of the water flow meter before and after each test run and at least once during each test 

run by comparing the water flow rate indicated by the flow meter to the mass of water 

collected from the outlet of the heat exchanger over a timed interval. Volume of the 

collected water shall be determined based on the water density calculated from section 

13, Eq. 8, using the water temperature measured at the flow meter. The uncertainty in the 

verification procedure used shall be 1 percent or less. The water flow rate determined by

the collection and weighing method shall be within 1 percent of the flow rate indicated by

the water flow meter. 

10.3 Scales. The scales used to weigh the appliance and test fuel charge shall be 

calibrated using NIST Traceable methods at least once every 6 months.

10.4 Moisture Meter. The moisture meter shall be calibrated per the 

manufacturer’s instructions and checked before each use.

10.5 Flue Gas Analyzers – In accordance with CSA B415.1-2010, Clause 6.8.
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11.0 Conditioning

11.1 Prior to testing, the noncatalytic appliance is to be operated for a minimum 

of 10 hours using a medium heat draw rate. Catalytic units shall be operated for a 

minimum of 50 hours using a medium heat draw rate. The pre-burn for the first test can 

be included as part of the conditioning requirement. If conditioning is included in preburn, then the appliance shall be aged with fuel meeting the specifications outlined in 

sections 12.2 with a moisture content between 19 and 25 percent on a dry basis. Operate 

the appliance at a medium burn rate (Category II or III) for at least 10 hours for 

noncatalytic appliances and 50 hours for catalytic appliances. Record and report hourly 

flue gas exit temperature data and the hours of operation. The aging procedure shall be 

conducted and documented by a testing laboratory.

12.0 Procedure

12.1 Appliance Installation. Assemble the appliance and parts in conformance 

with the manufacturer's written installation instructions. Clean the flue with an 

appropriately sized, wire chimney brush before each certification test series.

12.2 Fuel. Test fuel charge fuel shall be red (Quercus ruba L.) or white (Quercus

alba) oak 19 to 25 percent moisture content on a dry basis. Piece length shall be 80 

percent of the firebox depth rounded down to the nearest 1 inch (25mm) increment. For 

example, if the firebox depth is 46 inches (1168mm) the 4 x 4 piece length would be 36 

inches (46 inches x 0.8 = 36.8 inches round down to 36 inches). Pieces are to be placed in 

the firebox parallel to the longest firebox dimension. For fireboxes with sloped surfaces 

that create a non-uniform firebox length, the piece length shall be adjusted for each layer 

based on 80 percent of the length at the level where the layer is placed. Pieces are to be 
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spaced 3⁄4 inches (19 mm) apart on all faces. The first fuel layer may be assembled using 

fuel units consisting of multiple 4 x 4s consisting of single pieces with bottom and side 

spacers of 3 or more pieces if needed for a stable layer. The second layer may consist of 

fuel units consisting of no more than two pieces with spacers attached on the bottom and 

side. The top two layers of the fuel charge must consist of single pieces unless the fuel 

charge is only three layers. In that instance only the top layer must consist of single units. 

Three-quarter inch (19 mm) by 1.5 inch (38 mm) spacers shall be attached to the bottom 

of piece to maintain a 3⁄4 inch (19 mm) separation. When a layer consists of two or more 

units of 4 x 4s an additional 3⁄4 inch (19 mm) thick by 1.5 inch (38 mm) wide spacer shall 

be attached to the vertical face of each end of one 4 x 4, such that the 3⁄4 inch (19 mm) 

space will be maintained when two 4 x 4 units or pieces are loaded side by side. In cases 

where a layer contains an odd number of 4 x 4s one piece shall not be attached, but shall 

have spacers attached in a manner that will provide for the 3⁄4 inch (19 mm) space to be 

maintained. (See Figure 1). Spacers shall be attached perpendicular to the length of the 4 

x 4s such that the edge of the spacer is 1 ± 0.25 inch from the end of the 4 x 4s in the 

previous layers. Spacers shall be red or white oak and will be attached with either nails 

(non-galvanized), brads or oak dowels. The use of kiln-dried wood is not allowed.

12.2.1 Using a fuel moisture meter as specified in 6.7 of the test method, 

determine the fuel moisture for each test fuel piece used for the test fuel load by

averaging at least five fuel moisture meter readings measured parallel to the wood grain. 

Penetration of the moisture meter insulated electrodes for all readings shall be 1/4 the 

thickness of the fuel piece or 19 mm (3/4 in.), whichever is lesser. One measurement 

from each of three sides shall be made at approximately 3 inches from each end and the 
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center. Two additional measurements shall be made centered between the other three 

locations. Each individual moisture content reading shall be in the range of 18 to 28 

percent on a dry basis. The average moisture content of each piece of test fuel shall be in 

the range of 19 to 25 percent. It is not required to measure the moisture content of the 

spacers. Moisture shall not be added to previously dried fuel pieces except by storage 

under high humidity conditions and temperature up to 100oF. Fuel moisture shall be 

measured within four hours of using the fuel for a test.

12.2.2 Firebox Volume. Determine the firebox volume in cubic feet. Firebox 

volume shall include all areas accessible through the fuel loading door where firewood 

could reasonably be placed up to the horizontal plane defined by the top of the loading 

door. A drawing of the firebox showing front, side and plan views or an isometric view 

with interior dimensions shall be provided by the manufacturer and verified by the 

laboratory. Calculations for firebox volume from computer aided design (CAD) software 

programs are acceptable and shall be included in the test report if used. If the firebox 

volume is calculated by the laboratory the firebox drawings and calculations shall be 

included in the test report.

12.2.3 Test Fuel charge. Test fuel charges shall be determined by multiplying the 

firebox volume by 10 pounds (4.54 kg) per ft3 (28L), or a higher load density as 

recommended by the manufacturer’s printed operating instructions, of wood (as used wet 

weight). Select the number of pieces of standard fuel that most nearly match this target 

weight. This is the standard fuel charge for all tests. For example, if the firebox loading 

area volume is 10 ft3(280L) and the firebox depth is 46 inches (1168 mm), test fuel 

charge target is 100 lbs (45 kg) minimum and the piece length is 36 inches (914 mm). If 8 
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- 4 x 4s, 36 inches long weigh 105 lbs (48 kg), use 8 pieces for each test fuel charge. All 

test fuel charges will be of the same configuration.

12.3 Sampling Equipment. Prepare the particulate emission sampling equipment 

as defined by ASTM E2515-10 “Standard Test Method For Determination of Particulate 

Matter Emissions Collected In a Dilution Tunnel.”

12.4 Appliance Start-Up. The appliance shall be fired with wood fuel of any

species, size and moisture content at the laboratories discretion to bring it up to operating 

temperature. Operate the appliance until the water is heated to the upper operating control 

limit and has cycled at least two times. Then remove all unburned fuel, zero the scale and 

verify the scales accuracy using dead weights.

12.4.1 Pre-Test Burn Cycle. Reload appliance with oak wood and allow it to burn 

down to the specified coal bed weight. The Pre-Test burn cycle fuel charge weight shall 

be within ±10 percent of the test fuel charge weight. Piece size and length shall be 

selected such that charcoalization is achieved by the time the fuel charge has burned 

down to the required coal bed weight. Pieces with a maximum thickness of 

approximately 2 inches have been found to be suitable. Charcoalization is a general 

condition of the test fuel bed evidenced by an absence of large pieces of burning wood in 

the coal bed and the remaining fuel pieces being brittle enough to be broken into smaller 

charcoal pieces with a metal poker. Manipulations to the fuel bed prior to the start of the 

test run are to be done to achieve charcoalization while maintaining the desired heat 

output rate. During the pre-test burn cycle and at least one hour prior to starting the test 

run, adjust water flow to the heat exchanger to establish the target heat draw for the test. 
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For the first test run the heat draw rate shall be equal to the manufacturer’s rated heat 

output capacity.

12.4.1.1 Allowable Adjustments. Fuel addition or subtractions, and coal bed 

raking shall be kept to a minimum but are allowed up to 15 minutes prior to the start of 

the test run. For the purposes of this method, coal bed raking is the use of a metal tool 

(poker) to stir coals, break burning fuel into smaller pieces, dislodge fuel pieces from 

positions of poor combustion, and check for the condition of charcoalization. Record all 

adjustments to and additions or subtractions of fuel, and any other changes to the 

appliance operations that occur during pretest ignition period. During the 15-minute 

period prior to the start of the test run, the wood heater loading door shall not be open 

more than a total of 1 minute. Coal bed raking is the only adjustment allowed during this 

period.

12.4.2 Coal Bed Weight. The appliance is to be loaded with the test fuel charge 

when the coal bed weight is between 10 percent and 20 percent of the test fuel charge 

weight. Coals may be raked as necessary to level the coal bed but may only be raked and 

stirred once between 15 to 20 minutes prior to the addition of the test fuel charge.

12.5 Test Runs. For all test runs, the return water temperature to the hydronic 

heater must be equal to or greater than 120°F. Aquastat or other heater output control 

device settings that are adjustable shall be set using manufacturer specifications, either as 

factory set or in accordance with the owner’s manual, and shall remain the same for all 

burn categories.

Complete a test run in each heat output rate category, as follows:
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12.5.1 Test Run Start. Once the appliance is operating normally and the pretest 

coal bed weight has reached the target value per 12.4.2, tare the scale and load the full 

test charge into the appliance. Time for loading shall not exceed 5 minutes. The actual 

weight of the test fuel charge shall be measured and recorded within 30 minutes prior to 

loading. Start all sampling systems. 

12.5.1.1 Record all water temperatures, differential water temperatures and water 

flow rates at time intervals of one minute or less. 

12.5.1.2 Record particulate emissions data per the requirements of ASTM E2515.

12.5.1.3 Record data needed to determine Overall Efficiency (SLM) per the 

requirements of CSA B415.1-2010 Clauses 6.2.1, 6.2.2, 6.3, 8.5.7, 10.4.3 (a), 10.4.3(f),

and 13.7.9.3

12.5.1.3.1 Measure and record the test room air temperature in accordance with 

the requirements of Clauses 6.2.1, 8.5.7 and 10.4.3 (g).

12.5.1.3.2 Measure and record the flue gas temperature in accordance with the 

requirements of Clauses 6.2.2, 8.5.7 and 10.4.3 (f).

12.5.1.3.3 Determine and record the Carbon Monoxide (CO) and Carbon Dioxide 

(CO2) concentrations in the flue gas in accordance with Clauses 6.3, 8.5.7 and 10.4.3 (i) 

and (j).

12.5.1.3.4 Measure and record the test fuel weight per the requirements of Clauses 

8.5.7 and 10.4.3 (h).

12.5.1.3.5 Record the test run time per the requirements of Clause 10.4.3 (a).

12.5.1.4 Monitor the average heat output rate on the load side of the heat 

exchanger. If the heat output rate gets close to the upper or lower limit of the target range 
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(±5 percent) adjust the water flow through the heat exchanger to compensate. Make 

changes as infrequently as possible while maintaining the target heat output rate. The first 

test run shall be conducted at the category IV heat output rate to validate that the 

appliance is capable of producing the manufacturer’s rated heat output capacity.

12.5.2 Test Fuel Charge Adjustment. It is acceptable to adjust the test fuel charge 

(i.e., reposition) once during a test run if more than 60 percent of the initial test fuel 

charge weight has been consumed and more than 10 minutes have elapsed without a 

measurable (1 lb or 0. 5 kg ) weight change while the operating control is in the demand 

mode. The time used to make this adjustment shall be less than 60 seconds.

12.5.3 Test Run Completion. The test run is completed when the remaining 

weight of the test fuel charge is 0.0 lb (0.0 kg). End the test run when the scale has 

indicated a test fuel charge weight of 0.0 lb (0.0 kg) or less for 30 seconds.

12.5.3.1 At the end of the test run, stop the particulate sampling train and Overall 

Efficiency (SLM) measurements, and record the run time, and all final measurement 

values.

12.5.4 Heat Output Capacity Validation. The first test run must produce a heat 

output rate that is within 10 percent of the manufacturer’s rated heat output capacity

(Category IV) throughout the test run and an average heat output rate within 5 percent of 

the manufacturer’s rated heat output capacity. If the appliance is not capable of producing 

a heat output within these limits, the manufacturer’s rated heat output capacity is 

considered not validated and testing is to be terminated. In such cases, the tests may be 

restarted using a lower heat output capacity if requested by the manufacturer.
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12.5.5 Additional Test Runs. Using the Manufacturer’s Rated Heat Output 

Capacity as a basis, conduct a test for additional heat output categories as specified in 4.3. 

It is not required to run these tests in any particular order.

12.5.6 Alternative Heat Output Rate for Category I. If an appliance cannot be 

operated in the category I heat output range due to stopped combustion, two test runs 

shall be conducted at heat output rates within Category II. When this is the case, the 

weightings for the weighted averages indicated in Table 2 shall be the average of the 

category I and II weightings and shall be applied to both category II results. Appliances 

that are not capable of operation within Category II (<25 percent of maximum) cannot be 

evaluated by this test method.

12.5.6.1 Stopped Fuel Combustion. Evidence that an appliance cannot be operated 

at a category I heat output rate due to stopped fuel combustion shall include 

documentation of two or more attempts to operate the appliance in burn rate Category I

and fuel combustion has stopped prior to complete consumption of the test fuel charge. 

Stopped fuel combustion is evidenced when an elapsed time of 60 minutes or more has 

occurred without a measurable (1 lb or 0.5 kg) weight change in the test fuel charge while 

the appliance operating control is in the demand mode. Report the evidence and the 

reasoning used to determine that a test in burn rate Category I cannot be achieved. For 

example, two unsuccessful attempts to operate at an output rate of 10 percent of the rated 

output capacity are not sufficient evidence that burn rate Category I cannot be achieved.

12.5.7 Appliance Overheating. Appliances shall be capable of operating in all heat 

output categories without overheating to be rated by this test method. Appliance 

overheating occurs when the rate of heat withdrawal from the appliance is lower than the 
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rate of heat production when the unit control is in the idle mode. This condition results in 

the water in the appliance continuing to increase in temperature well above the upper 

limit setting of the operating control. Evidence of overheating includes: 1 hour or more of 

appliance water temperature increase above the upper temperature set-point of the 

operating control, exceeding the temperature limit of a safety control device (independent 

from the operating control), boiling water in a non-pressurized system or activation of a 

pressure or temperature relief valve in a pressurized system.

12.6 Additional Test Runs. The testing laboratory may conduct more than one test 

run in each of the heat output categories specified in section 4.4.1. If more than one test 

run is conducted at a specified heat output rate, the results from at least two-thirds of the 

test runs in that heat output rate category shall be used in calculating the weighted 

average emission rate (See section 15.1.14). The measurement data and results of all test 

runs shall be reported regardless of which values are used in calculating the weighted 

average emission rate.

13.0 Calculation of Results

13.1 Nomenclature

ET – Total particulate emissions for the full test run as determined per ASTM E2515 in 

grams

Eg/MJ – Emissions rate in grams per mega joule of heat output.

Elb/mmBtu output – Emissions rate in pounds per million Btu’s of heat output.

Eg/kg – Emissions factor in grams per kilogram of dry fuel burned.

Eg/hr – Emissions factor in grams per hour.

HHV – Higher Heating Value of fuel = 8600 Btu/lb (19.990 MJ/kg)
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LHV – Lower Heating Value of fuel = 7988 Btu/lb (18.567 MJ/kg)

ΔT – Temperature difference between water entering and exiting the heat exchanger.

Qout − Total heat output in BTU’s (mega joules).

Qin − Total heat input available in test fuel charge in BTU’s (mega joules).

M − Mass flow rate of water in lb/min (kg/min).

Vi – Volume of water indicated by a totalizing flow meter at the ith reading in gallons 

(liters).

Vf – Volumetric Flow rate of water in heat exchange system in gallons per minute 

(liters/min).

Θ – Total length of test run in hours

ti − Data sampling interval in minutes.

ηdel – Delivered heating efficiency in percent.

Fi − Weighting factor for heat output category i. (See Tables 2A and 2B)

T1 – Temperature of water at the inlet on the supply side of the heat exchanger.

T2 – Temperature of the water at the outlet on the supply side of the heat exchanger.

T3–Temperature of water at the inlet to the load side of the heat exchanger.

TIavg − Average temperature of the appliance and water at start of the test.

TIavg = (T1 + T2)/2 at the start of the test, °F Eq.1

TFavg – Average temperature of the appliance and water at the end of the test.

TFavg = (T1 + T2)/2 at the end of the test, °F Eq.2

MC – Fuel moisture content in percent dry basis.

MCi – Average moisture content of individual 4 x 4 fuel pieces in percent dry basis.

MCsp – Moisture content of spacers assumed to be 10 percent dry basis.
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σ – Density of water in pounds per gallon.

Cp – Specific Heat of Water in Btu /lb °-F.

Csteel − Specific Heat of Steel (0.1 Btu/ lb -oF)

Wfuel – Fuel charge weight in pounds (kg)

Wi – Weight of individual fuel 4 x 4 pieces in pounds (kg)

Wsp – Weight of all spacers used in a fuel load in pounds (kg)

Wapp − Weight of empty appliance in pounds

Wwat– Weight of water in supply side of the system in pounds

13.2 After the test is completed, determine the particulate emissions ET in 

accordance with ASTM E2515.

13.3 Determine Average Fuel Load Moisture Content

MCAve = [[ Σ Wi x MCi] + [ Wsp x MCsp ]] ÷ Wfuel, % Eq. 3

13.4 Determine heat input

Qin = (Wfuel/(1+(MC/100))) x HHV, BTU Eq. 4

Qin LHV = (Wfuel/(1+(MC/100))) x LHV, BTU Eq. 5

13.5 Determine heat output and efficiency

13.5.1 Determine heat output as:

Qout = Σ [Heat output determined for each sampling time interval]+ Change in heat stored in 

the appliance.

 ( ) ( ) ( ) out pi i i i Wapp CSteel CpaWwater TFavg TI avg Q   C  T  M  t     

, BTU Eq. 6

Note: The subscript (i) indicates the parameter value for sampling time interval ti.

Mi = Mass flow rate = gal/min x Density of Water (lb/gal) = lb/min

Mi=Vfi · σi, lb/min Eq. 7
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Σi = (62.56 + ( -.0003413 x T3i) + ( -.00006225 x T3i

2

)) 0.1337, lbs/galEq. 8

Cp = 1.0014 + ( -.000003485 x T3i) Btu/lb-oF Eq. 9

Csteel = 0.1 Btu/lb-oF

Cpa = 1.0014 + (-.000003485 X (TIavg +TFavg)/2) , Btu/lb-oF Eq. 10

Vfi = (Vi –Vi-1)/(ti-ti-1), gal/min Eq. 11

Note: Vi is the total water volume at the end of interval i and Vi-1 is the total water volume 

at the beginning of the time interval. This calculation is necessary when a totalizing type 

water meter is used.

13.5.2 Determine Heat output rate as:

Heat Output Rate = Qout/Θ, BTU/hr Eq. 12

13.5.3 Determine Emission Rates and Emission Factors as:

Eg/MJ = ET/(Qout x 0.001055), g/MJ Eq. 13

Elb/MM BTU output = (ET/453.59)/(Qoutput x 10-6), lb/MMBtu Out Eq. 14

Eg/kg = ET/(Wfuel/(1+MC/100)), g/dry kg Eq, 15

Eg/hr = ET/Θ , g/hr Eq. 16

13.5.4 Determine delivered efficiency as:

ηdel = (Qout/Qin) x 100, % Eq. 17

ηdel LHV = (Qout/Qin LHV) x 100, % Eq. 18

13.5.5 Determine ηSLM - Overall Efficiency (SLM) using Stack Loss 

For determination of the average overall thermal efficiency (ηSLM) for the test run, use the 

data collected over the full test run and the calculations in accordance with CSA B415.1-

2010, Clause 13.7 except for 13.7.2 (e), (f), (g), and (h), use the following average fuel 
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properties for oak: percent C = 50.0, percent H = 6.6, percent O = 43.2, percent Ash = 0.2 

percent.

13.5.5.1 Whenever the CSA B415.1-2010 overall efficiency is found to be lower 

than the overall efficiency based on load side measurements, as determined by Eq. 16 of 

this method, section 14.1.7 of the test report must include a discussion of the reasons for 

this result.

13.6 Weighted Average Emissions and Efficiency

13.6.1 Determine the weighted average emission rate and delivered efficiency from 

the individual tests in the specified heat output categories. The weighting factors (Fi) are 

derived from an analysis of ASHRAE Bin Data which provides details of normal building 

heating requirements in terms of percent of design capacity and time in a particular 

capacity range – or “bin” - over the course of a heating season. The values used in this 

method represent an average of data from several cities located in the northern United 

States.

Weighted average delivered efficiency: ηavg = Σ ηi x Fi, % Eq. 17

Weighted average emissions: Eavg = ΣEi x Fi, % Eq. 18

13.7 Average Heat Output (Qout-8hr) and Efficiency ((ηavg-8hr) for 8 hour burn time.

13.7.1 Units tested under this standard typically require infrequent fuelling, 8 to 12 

hours intervals being typical. Rating unit’s based on an Average Output sustainable over an 

8 hour duration will assist consumers in appropriately sizing units to match the theoretical 

heat demand of their application.

13.7.2 Calculations:

Qout-8hr = X1 + { ( 8 - Y1 ) x [ ( X2 - X1 ) / ( Y2 - Y1 ) ] }, % Eq. 19
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ηavg-8hr = ηdel1 + { ( 8 - Y1 ) x [ (ηdel2 - ηdel1 ) / ( Y2 - Y1 ) ] }, % Eq. 20

Where:

Y1 = Test Duration just above 8 hrs

Y2 = Test Duration just below 8 hrs

X1 = Actual Load for duration Y1

X2 = Actual Load for duration Y2

ηdel1 = Average Delivered Efficiency for duration Y1

ηdel2 = Average Delivered Efficiency for duration Y2

13.7.2.1 Determine the Test Durations and Actual Load for each Category as 

recorded in Table 1A.

13.7.2.2 Determine the data point that has the nearest duration greater than 8 hrs. X1 = 

Actual Load, 

Y1 = Test Duration and

ηdel1 = Average Delivered Efficiency for this data point.

13.7.2.3 Determine the data point that has the nearest duration less than 8 hrs. 

X2 = Actual Load, 

Y2 = Test Duration and 

ηdel2 = Average Delivered Efficiency for this data point.

13.7.2.4 Example:

Category Actual Load Duration

Category Actual Load Duration ηdel

(Btu/Hr) (Hr) (%)

1 15,000 10.2 70.0

2 26,000 8.4 75.5
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3 50,000 6.4 80.1

4 100,000 4.7 80.9

Category 2 Duration is just above 8 hours, therefore: X1 = 26,000 BTU/hr, ηdel1 = 75.5% 

and Y1 = 8.4 Hrs

Category 3 Duration is just below 8 hours, therefore: X2 = 50,000 BTU/hr, ηdel2 = 80.1% 

and Y2 = 6.4 Hrs

Qout-8hr = 26,000 + {(8 - 8.4) x [(50,000 - 26,000) / (6.4 - 8.4)]}

= 30,800 BTU/hr

ηavg-8hr = 75.5 + {(8 - 8.4) x [(80.1 – 75.5) / (6.4 - 8.4)]} = 76.4%

14.0 Report

14.1.1 The report shall include the following.

14.1.2 Name and location of the laboratory conducting the test.

14.1.3 A description of the appliance tested and its condition, date of receipt and 

dates of tests.

14.1.4 A statement that the test results apply only to the specific appliance tested.

14.1.5 A statement that the test report shall not be reproduced except in full, 

without the written approval of the laboratory.

14.1.6 A description of the test procedures and test equipment including a 

schematic or other drawing showing the location of all required test equipment. Also, a 

description of test fuel sourcing, handling and storage practices shall be included.

14.1.7 Details of deviations from, additions to or exclusions from the test method, 

and their data quality implications on the test results (if any), as well as information on 

specific test conditions, such as environmental conditions.

14.1.8 A list of participants and observers present for the tests.
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14.1.9 Data and drawings indicating the fire box size and location of the fuel 

charge.

14.1.10 Drawings and calculations used to determine firebox volume.

14.1.11 Information for each test run fuel charge including piece size, moisture 

content, and weight.

14.1.12 All required data for each test run shall be provided in spreadsheet format. 

Formulae used for all calculations shall be accessible for review.

14.1.13 Test run duration for each test.

14.1.14 Calculated results for delivered efficiency at each burn rate and the 

weighted average Emissions reported as total emissions in grams, pounds per million Btu 

of delivered heat, grams per mega-joule of delivered heat, grams per kilogram of dry fuel 

and grams per hour. Results shall be reported for each heat output category and the 

weighted average.

14.1.15 Tables 1A, 1B, 1C and 2 must be used for presentation of results in test 

reports.

14.1.16 A statement of the estimated uncertainty of measurement of the emissions 

and efficiency test results.

14.1.17 Raw data, calibration records, and other relevant documentation shall be 

retained by the laboratory for a minimum of 7 years.

15.0 Precision and Bias

15.1 Precision—It is not possible to specify the precision of the procedure in 

Draft Test because the appliance operation and fueling protocols and the appliances 
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themselves produce variable amounts of emissions and cannot be used to determine 

reproducibility or repeatability of this measurement method.

15.2 Bias—No definitive information can be presented on the bias of the 

procedure in Draft Test Method 28 WHH for measuring solid fuel burning hydronic 

heater emissions because no material having an accepted reference value is available.

16.0 Keywords

16.1 Solid fuel, hydronic heating appliances, wood-burning hydronic heaters.

Table 1A. Data Summary Part A

Table 1B. Data Summary Part B

Table 1C: Hangtag Information
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Table 2. Year Round Use Weighting
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8. Part 60 Appendix A-8 is amended by adding Method 28WHH-PTS to follow 

Method 28WHH to read as follows:

A Test Method for Certification of Cord Wood-Fired Hydronic Heating Appliances with 

Partial Thermal Storage: Measurement of Particulate Matter (PM) and Carbon Monoxide 

(CO) Emissions and Heating Efficiency of Wood-Fired Hydronic Heating Appliances 

with Partial Thermal Storage

1.0 Scope and Application

1.1 This test method applies to wood-fired hydronic heating appliances with heat 

storage external to the appliance. The units typically transfer heat through circulation of a 

liquid heat exchange media such as water or a water-antifreeze mixture. Throughout this 

document, the term “water” will be used to denote any of the heat transfer liquids 

approved for use by the manufacturer. 

1.2 The test method measures PM and CO emissions and delivered heating 

efficiency at specified heat output rates referenced against the appliance’s rated heating 

capacity as specified by the manufacturer and verified under this test method. 

1.3 PM emissions are measured by the dilution tunnel method as specified in the 

EPA Method 28 WHH and the standards referenced therein with the exceptions noted in 

Section 12.5.9. Delivered Efficiency is measured by determining the fuel energy input 

and appliance output. Heat output is determined through measurement of the flow rate 

and temperature change of water circulated through a heat exchanger external to the 

appliance and the increase in energy of the external storage. Heat input is determined 

from the mass of dry wood fuel and its higher heating value (HHV). Delivered efficiency

does not attempt to account for pipeline loss. 
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1.4 Products covered by this test method include both pressurized and nonpressurized hydronic heating appliances intended to be fired with wood and for which the 

manufacturer specifies for indoor or outdoor installation. The system, which includes the 

heating appliance and external storage, is commonly connected to a heat exchanger by 

insulated pipes and normally includes a pump to circulate heated liquid. These systems 

are used to heat structures such as homes, barns and greenhouses. They also provide heat 

for domestic hot water, spas and swimming pools. 

1.5 Distinguishing features of products covered by this standard include: 

1.5.1 The manufacturer specifies the application for either indoor or outdoor 

installation. 

1.5.2 A firebox with an access door for hand loading of fuel. 

1.5.3 Typically an aquastat mounted as part of the appliance that controls 

combustion air supply to maintain the liquid in the appliance within a predetermined 

temperature range provided sufficient fuel is available in the firebox. The appliance may

be equipped with other devices to control combustion. 

1.5.4 A chimney or vent that exhausts combustion products from the appliance. 

1.5.5 A liquid storage system, typically water, which is not large enough to accept 

all of the heat produced when a full load of wood is burned and the storage system starts 

a burn cycle at 125°F. 

1.5.6 The heating appliances require external thermal storage and these units will 

only be installed as part of a system which includes thermal storage. The manufacturer 

specifies the minimum amount of thermal storage required. However, the storage system 
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shall be large enough to ensure that the boiler (heater) does not cycle, slumber, or go into 

an off-mode when operated in a Category III load condition (See section 4.3). 

1.6 The values stated are to be regarded as the standard whether in I-P or SI units. 

The values given in parentheses are for information only. 

2.0 Summary of Method and References 

2.1 PM and CO emissions are measured from a wood–fired hydronic heating 

appliance burning a prepared test fuel charge in a test facility maintained at a set of 

prescribed conditions. Procedures for determining heat output rates, PM and CO 

emissions, and efficiency and for reducing data are provided. 

2.2 Referenced Documents 

2.2.1 EPA Standards 

2.2.1.1 Method 28 Certification and Auditing of Wood Heaters 

2.2.1.2 Method 28 WHH Measurement of Particulate Emissions and Heating 

Efficiency of Wood-Fired Hydronic Heating Appliances and the standards referenced 

therein.

2.2.2 Other Standards 

2.2.2.1 CAN/CSA-B415.1-2010 Performance Testing of Solid-Fuel-Burning 

Heating Appliances 

3.0 Terminology 

3.1 Definitions 

3.1.1 Hydronic Heating – A heating system in which a heat source supplies 

energy to a liquid heat exchange media such as water that is circulated to a heating load 

and returned to the heat source through pipes. 
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3.1.2 Aquastat – A control device that opens or closes a circuit to control the rate 

of fuel consumption in response to the temperature of the heating media in the heating 

appliance. 

3.1.3 Delivered Efficiency – The percentage of heat available in a test fuel charge 

that is delivered to a simulated heating load or the storage system as specified in this test 

method. 

3.1.4 Emission factor – the emission of a pollutant expressed in mass per unit of 

energy (typically) output from the boiler/heater

3.1.5 Emission index – the emission of a pollutant expressed in mass per unit 

mass of fuel used 

3.1.6 Emission rate – the emission of a pollutant expressed in mass per unit time 

3.1.7 Manufacturer’s Rated Heat Output Capacity −The value in Btu/hr (MJ/hr) 

that the manufacturer specifies that a particular model of hydronic heating appliance is 

capable of supplying at its design capacity as verified by testing, in accordance with 

section 12.5.4. 

3.1.8 Heat output rate − The average rate of energy output from the appliance 

during a specific test period in Btu/hr (MJ/hr) 

3.1.9 Firebox − The chamber in the appliance in which the test fuel charge is 

placed and combusted. 

3.1.10 NIST – National Institute of Standards and Technology

3.1.11 Test fuel charge − The collection of test fuel placed in the appliance at the 

start of the emission test run. 
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3.1.12 Test Run – An individual emission test which encompasses the time 

required to consume the mass of the test fuel charge. The time of the test run also 

considers the time for the energy to be drawn from the thermal storage. 

3.1.13 Test Run Under “Cold-to-Cold” Condition – under this test condition the 

test fuel is added into an empty chamber along with kindling and ignition materials 

(paper). The boiler/heater at the start of this test is typically 125o to 130o F. 

3.1.14 Test Run Under “Hot-to-Hot” Condition – under this test condition the test 

fuel is added onto a still-burning bed of charcoals produced in a pre-burn period. The 

boiler/heater water is near its operating control limit at the start of the test. 

3.1.15 Overall Efficiency, also known as Stack Loss Efficiency – The efficiency

for each test run as determined using the CSA B415.1-2010 Stack Loss Method (SLM). 

3.1.16 Phases of a Burn Cycle. The “startup phase” is defined as the period from 

the start of the test until 15 percent of the test fuel charge is consumed. The “steady state 

phase” is defined as the period from the end of the startup phase to a point at which 80

percent of the test fuel charge is consumed. The “end phase” is defined as the time from 

the end of the steady state period to the end of the test. 

3.1.17 Thermopile - A device consisting of a number of thermocouples connected 

in series, used for measuring differential temperature. 

3.1.18 Slumber Mode – This is a mode in which the temperature of the water in 

the boiler/heater has exceeded the operating control limit and the control has changed the 

boiler/heater fan speed, dampers, and/or other operating parameters to minimize the heat 

output of the boiler/heater. 

4.0 Summary of Test Method 
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4.1 Dilution Tunnel. Emissions are determined using the “dilution tunnel” method 

specified in EPA Method 28 WHH and the standards referenced therein. The flow rate in 

the dilution tunnel is maintained at a constant level throughout the test cycle and 

accurately measured. Samples of the dilution tunnel flow stream are extracted at a 

constant flow rate and drawn through high efficiency filters. The filters are dried and 

weighed before and after the test to determine the emissions collected and this value is 

multiplied by the ratio of tunnel flow to filter flow to determine the total particulate 

emissions produced in the test cycle. 

4.2 Efficiency. The efficiency test procedure takes advantage of the fact that this 

type of system delivers heat through circulation of the heated liquid (water) from the 

system to a remote heat exchanger (e.g. baseboard radiators in a room) and back to the 

system. Measurements of the cooling water temperature difference as it enters and exits 

the test system heat exchanger along with the measured flow rate allow for an accurate 

determination of the useful heat output of the appliance. Also included in the heat output 

is the change in the energy content in the storage system during a test run. Energy input 

to the appliance during the test run is determined by weight of the test fuel charge, 

adjusted for moisture content, multiplied by the Higher Heating Value. Additional 

measurements of the appliance weight and temperature at the beginning and end of a test 

cycle are used to correct for heat stored in the appliance. Overall Efficiency (SLM) is 

determined using the CSA B415.1-2010 stack loss method for data quality assurance 

purposes. 

4.3 Operation. Four test categories are defined for use in this method. These are: 
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4.3.1 Category I: A heat output of 15 percent or less of Manufacturer’s Rated 

Heat Output Capacity. 

4.3.2 Category II: A heat output of 16 percent to 24 percent of Manufacturer’s 

Rated Heat Output Capacity. 

4.3.3 Category III: A heat output of 25 percent to 50 percent of Manufacturer’s 

Rated Heat Output Capacity. 

4.3.4 Category IV: Manufacturer’s Rated Heat Output Capacity. 

These heat output categories refer to the output from the system by way of the load heat 

exchanger installed for the test. The output from just the boiler/heater part of the system 

may be higher for all or part of a test, as part of this boiler/heater output goes to storage. 

For the Category III and IV runs, appliance operation is conducted on a hot-to-hot test 

cycle meaning that the appliance is brought to operating temperature and a coal bed is 

established prior to the addition of the test fuel charge and measurements are made for 

each test fuel charge cycle. The measurements are made under constant heat draw 

conditions within pre-determined ranges. No attempt is made to modulate the heat 

demand to simulate an indoor thermostat cycling on and off in response to changes in the 

indoor environment. 

For the Category I and II runs, the unit is tested with a “cold start.” 

At the manufacturer’s option, the Category II and III runs may be waived and it may be 

assumed that the particulate emission values and efficiency values determined in the 

start-up, steady-state, and end phases of Category I are applicable in Categories II and III 

for the purpose of determining the annual averages in lb/MMBtu and g/MJ (See section 

13). For the annual average in g/hr, the length of time for stored heat to be drawn from 
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thermal storage shall be determined for the test load requirements of the respective 

Category. 

All test operations and measurements shall be conducted by personnel of the 

laboratory responsible for the submission of the test report. 

5.0 Significance and Use 

5.1 The measurement of particulate matter emission and CO rates is an important 

test method widely used in the practice of air pollution control. 

5.1.1 These measurements, when approved by state or federal agencies, are often 

required for the purpose of determining compliance with regulations and statutes. 

5.1.2 The measurements made before and after design modifications are necessary

to demonstrate the effectiveness of design changes in reducing emissions and make this 

standard an important tool in manufacturer’s research and development programs. 

5.2 Measurement of heating efficiency provides a uniform basis for comparison of 

product performance that is useful to the consumer. It is also required to relate emissions 

produced to the useful heat production. 

5.3 This is a laboratory method and is not intended to be fully representative of all 

actual field use. It is recognized that users of hand-fired, wood-burning equipment have a 

great deal of influence over the performance of any wood-burning appliance. Some 

compromises in realism have been made in the interest of providing a reliable and 

repeatable test method. 

6.0 Test Equipment 
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6.1 Scale. A platform scale capable of weighing the boiler/heater under test and 

associated parts and accessories when completely filled with water to an accuracy of ± 

1.0 pound (± 0.5 kg) and a readout resolution of ± 0.2 pound (± 0.1 kg). 

6.2 Heat Exchanger. A water-to-water heat exchanger capable of dissipating the 

expected heat output from the system under test. 

6.3 Water Temperature Difference Measurement. A Type –T ‘special limits’ 

thermopile with a minimum of 5 pairs of junctions shall be used to measure the 

temperature difference in water entering and leaving the heat exchanger. The temperature 

difference measurement uncertainty of this type of thermopile is equal to or less than ± 

0.50 oF (± 0.25 oC). Other temperature measurement methods may be used if the 

temperature difference measurement uncertainty is equal to or less than ± 0.50oF (± 

0.25oC). This measurement uncertainty shall include the temperature sensor, sensor well 

arrangement, piping arrangements, lead wire, and measurement / recording system. The 

response time of the temperature measurement system shall be less than half of the time 

interval at which temperature measurements are recorded. 

6.4 Water Flow Meter. A water flow meter shall be installed in the inlet to the 

load side of the heat exchanger. The flow meter shall have an accuracy of ± 1 percent of 

measured flow. 

6.4.1 Optional - Appliance side water flow meter. A water flow meter with an 

accuracy of ± 1 percent of the flow rate is recommended to monitor supply side water 

flow rate. 

6.5 Optional Recirculation Pump. Circulating pump used during test to prevent 

stratification, in the boiler/heater, of liquid being heated. 
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6.6 Water Temperature Measurement – Thermocouples or other temperature 

sensors to measure the water temperature at the inlet and outlet of the load side of the 

heat exchanger must meet the calibration requirements specified in 10.1 of this method. 

6.7 Lab Scale – For measuring the moisture content of wood slices as part of the 

overall wood moisture determination. Accuracy of ± 0.01 pounds.

6.8 Flue Gas Temperature Measurement – Must meet the requirements of CSA 

B415.1-2010, Clause 6.2.2. 

6.9 Test Room Temperature Measurement – Must meet the requirements of CSA 

B415.1-2010, Clause 6.2.1. 

6.10 Flue Gas Composition Measurement – Must meet the requirements of CSA 

B415.1-2010, Clauses 6.3.1 through 6.3.3. 

6.11 Dilution Tunnel CO Measurement – In parallel with the flue gas composition 

measurements, the CO concentration in the dilution tunnel shall also be measured and 

reported at time intervals not to exceed one minute. This analyzer shall meet the zero and 

span drift requirements of CSA B415.1-2012. In addition the measurement repeatability

shall be better than ±15 ppm over the range of CO levels observed in the dilution tunnel. 

7.0 Safety 

7.1 These tests involve combustion of wood fuel and substantial release of heat 

and products of combustion. The heating system also produces large quantities of very

hot water and the potential for steam production and system pressurization. Appropriate 

precautions must be taken to protect personnel from burn hazards and respiration of 

products of combustion. 

8.0 Sampling, Test Specimens and Test Appliances 
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8.1 Test specimens shall be supplied as complete appliances, as described in 

marketing materials, including all controls and accessories necessary for installation in 

the test facility. A full set of specifications, installation and operating instructions, and 

design and assembly drawings shall be provided when the product is to be placed under 

certification of a third-party agency. The manufacturer’s written installation and 

operating instructions are to be used as a guide in the set-up and testing of the appliance 

and shall be part of the test record. 

8.2 The size, connection arrangement, and control arrangement for the thermal 

storage shall be as specified in the manufacturer’s documentation. It is not necessary to 

use the specific storage system that the boiler/heater will be marketed with. However, the 

capacity of the system used in the test cannot be greater than that specified as the 

minimum allowable for the boiler/heater. 

8.3 All system control settings shall be the as-shipped, default settings. These 

default settings shall be the same as those communicated in a document to the installer or 

end user. These control settings and the documentation of the control settings as to be 

provided to the installer or end user shall be part of the test record. 

8.4 Where the manufacturer defines several alternatives for the connection and 

loading arrangement, one shall be defined in the appliance documentation as the default 

or standard installation. It is expected that this will be the configuration for use with a 

simple baseboard heating system. This is the configuration to be followed for these tests. 

The manufacturer’s documentation shall define the other arrangements as optional or 

alternative arrangements. 

9.0 Preparation of Test Equipment 
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9.1 The appliance is to be placed on a scale capable of weighing the appliance 

fully loaded with a resolution of ± 0.2 lb (0.1 kg). 

9.2 The appliance shall be fitted with the type of chimney recommended or 

provided by the manufacturer and extending to 15 ± 0.5 feet (4.6 ± 0.15 m) from the 

upper surface of the scale. If no flue or chimney system is recommended or provided by 

the manufacturer, connect the appliance to a flue of a diameter equal to the flue outlet of 

the appliance. The flue section from the appliance flue collar to 8 ± 0.5 feet above the 

scale shall be single wall stove pipe and the remainder of the flue shall be double wall 

insulated class A chimney. 

9.3 Optional Equipment Use 

9.3.1 A recirculation pump may be installed between connections at the top and 

bottom of the appliance to minimize thermal stratification if specified by the 

manufacturer. The pump shall not be installed in such a way as to change or affect the 

flow rate between the appliance and the heat exchanger. 

9.3.2 If the manufacturer specifies that a thermal control valve or other device be 

installed and set to control the return water temperature to a specific set point, the valve 

or other device shall be installed and set per the manufacturer’s written instructions. 

9.4 Prior to filling the boiler/heater with water, weigh and record the appliance 

mass. 

9.5 Heat Exchanger 

9.5.1 Plumb the unit to a water-to-water heat exchanger with sufficient capacity to 

draw off heat at the maximum rate anticipated. Route hoses and electrical cables and 
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instrument wires in a manner that does not influence the weighing accuracy of the scale 

as indicated by placing dead weights on the platform and verifying the scale’s accuracy. 

9.5.2 Locate thermocouples to measure the water temperature at the inlet and 

outlet of the load side of the heat exchanger. 

9.5.3 Install a thermopile (or equivalent instrumentation) meeting the 

requirements of section 6.3 to measure the water temperature difference between the inlet 

and outlet of the load side of the heat exchanger

9.5.4 Install a calibrated water flow meter in the heat exchanger load side supply

line. The water flow meter is to be installed on the cooling water inlet side of the heat 

exchanger so that it will operate at the temperature at which it is calibrated. 

9.5.5 Place the heat exchanger in a box with 2 in. (50 mm) of expanded 

polystyrene (EPS) foam insulation surrounding it to minimize heat losses from the heat 

exchanger. 

9.5.6 The reported efficiency and heat output rate shall be based on measurements 

made on the load side of the heat exchanger. 

9.5.7 Temperature instrumentation per section 6.6 shall be installed in the 

appliance outlet and return lines. The average of the outlet and return water temperature 

on the supply side of the system shall be considered the average appliance temperature 

for calculation of heat storage in the appliance (TFavg and TIavg). Installation of a water

flow meter in the supply side of the system is optional. 

9.6 Storage Tank. The storage tank shall include a destratification pump as 

illustrated in Figure 1. The pump will draw from the bottom of the tank and return to the 

top as illustrated. Temperature sensors (TS1 and TS2 in Figure 1) shall be included to 
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measure the temperature in the recirculation loop. The valve plan in Figure 1 allows the 

tank recirculation loop to operate and the boiler/heater-to-heat exchanger loop to operate 

at the same time but in isolation. This would typically be done before the start of a test or 

following completion of a test to determine the end of test average tank temperature. The 

nominal flow rate in the storage tank recirculation loop can be estimated based on pump 

manufacturer’s performance curves and any significant restriction in the recirculation 

loop. 

9.7 Fill the system with water. Determine the total weight of the water in the 

appliance when the water is circulating. Verify that the scale indicates a stable weight 

under operating conditions. Make sure air is purged properly. 

10.0 Calibration and Standardization 

10.1 Water Temperature Sensors. Temperature measuring equipment shall be 

calibrated before initial use and at least semi-annually thereafter. Calibrations shall be in 

compliance with National Institute of Standards and Technology (NIST) Monograph 175, 

Standard Limits of Error. 

10.2 Heat Exchanger Load Side Water Flow Meter. 

10.2.1 The heat exchanger load side water flow meter shall be calibrated within

the flow range used for the test run using NIST-traceable methods. Verify the calibration 

of the water flow meter before and after each test run and at least once during each test 

run by comparing the water flow rate indicated by the flow meter to the mass of water 

collected from the outlet of the heat exchanger over a timed interval. Volume of the 

collected water shall be determined based on the water density calculated from section 

13, Eq. 12, using the water temperature measured at the flow meter. The uncertainty in 
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the verification procedure used shall be 1 percent or less. The water flow rate determined 

by the collection and weighing method shall be within 1 percent of the flow rate indicated 

by the water flow meter. 

10.3 Scales. The scales used to weigh the appliance and test fuel charge shall be 

calibrated using NIST-traceable methods at least once every 6 months. 

10.4 Flue Gas Analyzers – In accordance with CSA B415.1-2010, Clause 6.8. 

11.0 Conditioning 

11.1 Prior to testing, a non-catalytic appliance is to be operated for a minimum of 

10 hours using a medium heat draw rate. Catalytic units shall be operated for a minimum 

of 50 hours using a medium heat draw rate. The pre-burn for the first test can be included 

as part of the conditioning requirement. If conditioning is included in pre-burn, then the 

appliance shall be aged with fuel meeting the specifications outlined in section 12.2 with 

a moisture content between 19 and 25 percent on a dry basis. Operate the appliance at a 

medium heat output rate (Category II or III) for at least 10 hours for non-catalytic 

appliances and 50 hours for catalytic appliances. Record and report hourly flue gas exit 

temperature data and the hours of operation. The aging procedure shall be conducted and 

documented by a testing laboratory. 

12.0 Procedure 

12.1 Appliance Installation. Assemble the appliance and parts in conformance 

with the manufacturer's written installation instructions. Clean the flue with an 

appropriately sized, wire chimney brush before each certification test series. 

12.2 Fuel. Test fuel charge fuel shall be red (Quercus ruba L.) or white (Quercus Alba) 

oak 19 to 25 percent moisture content on a dry basis. Piece length shall be 80 percent of 
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the firebox depth rounded down to the nearest 1 inch (25mm) increment. For example, if 

the firebox depth is 46 inches (1168mm) the piece length would be 36 inches (46 inches x 

0.8 = 36.8 inches round down to 36 inches). Pieces are to be placed in the firebox parallel 

to the longest firebox dimension. For fireboxes with sloped surfaces that create a nonuniform firebox length, the piece length shall be adjusted for each layer based on 80

percent of the length at the level where the layer is placed. The test fuel shall be cord 

wood with cross section dimensions and weight limits as defined in CSA B415.1-2010, 

section 8.3, Table 4. The use of dimensional lumber is not allowed. 

12.2.1 Select three pieces of cord wood from the same batch of wood as the test 

fuel and the same weight as the average weight of the pieces in the test load ± 1.0 lb.

From each of these three pieces, cut three slices. Each slice shall be 1⁄2” to 3⁄4” thick. One 

slice shall be cut across the center of the length of the piece. The other two slices shall be 

cut half way between the center and the end. Immediately measure the mass of each piece 

in pounds. Dry each slice in an oven at 220°F for 24 hours or until no further weight 

change occurs. The slices shall be arranged in the oven so as to provide separation 

between faces. Remove from the oven and measure the mass of each piece again as soon 

as practical in pounds. 

The moisture content of each slice, on a dry basis shall be calculated as: 

MCslice = 100 ∙ (WSliceWet – WSliceDry)

 WSliceDry

Where: 

WSliceWet = weight of the slice before drying in pounds 

WSliceDry = weight of the slice after drying in pounds 
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MCSlice = moisture content of the slice in % dry basis 

The average moisture content of the entire test load (MC) shall be determined 

using Eq. 6. Each individual slice shall have a moisture content in the range of 18 percent 

to 28 percent on a dry basis. The average moisture content for the test fuel load shall be 

in the range of 19 percent to 25 percent. Moisture shall not be added to previously dried 

fuel pieces except by storage under high humidity conditions and temperature up to 

100oF. Fuel moisture measurement shall begin within four hours of using the fuel batch 

for a test. Use of a pin-type meter to estimate the moisture content prior to a test is 

recommended. 

12.2.2 Firebox Volume. Determine the firebox volume in cubic feet. Firebox 

volume shall include all areas accessible through the fuel loading door where firewood 

could reasonably be placed up to the horizontal plane defined by the top of the loading 

door. A drawing of the firebox showing front, side and plan views or an isometric view 

with interior dimensions shall be provided by the manufacturer and verified by the 

laboratory. Calculations for firebox volume from computer aided design (CAD) software 

programs are acceptable and shall be included in the test report if used. If the firebox 

volume is calculated by the laboratory the firebox drawings and calculations shall be 

included in the test report. 

12.2.3 Test Fuel charge. Test fuel charges shall be determined by multiplying the 

firebox volume by 10 pounds (4.54 kg) per ft3(28L), or a higher load density as 

recommended by the manufacturer’s printed operating instructions, of wood (as used wet 

weight). Select the number of pieces of cord wood that most nearly match this target 
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weight. However, the test fuel charge cannot be less than the target of 10 pounds (4.54 

kg) per ft3(28L). 

12.3 Sampling Equipment. Prepare the particulate emission sampling equipment 

as defined by EPA Method 28 WHH and the standards referenced therein. 

12.4 Appliance Start-Up. The appliance shall be fired with wood fuel of any

species, size and moisture content at the laboratories discretion to bring it up to operating 

temperature. Operate the appliance until the water is heated to the upper operating control 

limit and has cycled at least two times. Then remove all unburned fuel, zero the scale and 

verify the scales accuracy using dead weights.

12.4.1 Start-up Procedure for Category III and IV test runs, “hot-to-hot” 

12.4.1.1 Pre-Test Burn Cycle. Following appliance start-up (section 12.4), reload 

appliance with oak cord wood and allow it to burn down to the specified coal bed weight.

The pre-test burn cycle fuel charge weight shall be within ±10 percent of the test fuel 

charge weight. Piece size and length shall be selected such that charcoalization is 

achieved by the time the fuel charge has burned down to the required coal bed weight. 

Pieces with a maximum thickness of approximately 2 inches have been found to be 

suitable. Charcoalization is a general condition of the test fuel bed evidenced by an 

absence of large pieces of burning wood in the coal bed and the remaining fuel pieces 

being brittle enough to be broken into smaller charcoal pieces with a metal poker. 

Manipulations to the fuel bed prior to the start of the test run are to be done to achieve 

charcoalization while maintaining the desired heat output rate. During the pre-test burn 

cycle and at least one hour prior to starting the test run, adjust water flow to the heat 
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exchanger to establish the target heat draw for the test. For the first test run the heat draw 

rate shall be equal to the manufacturer’s rated heat output capacity. 

12.4.1.2 Allowable Adjustments. Fuel addition or subtractions, and coal bed 

raking shall be kept to a minimum but are allowed up to 15 minutes prior to the start of 

the test run. For the purposes of this method, coal bed raking is the use of a metal tool 

(poker) to stir coals, break burning fuel into smaller pieces, dislodge fuel pieces from 

positions of poor combustion, and check for the condition of charcoalization. Record all 

adjustments to and additions or subtractions of fuel, and any other changes to the 

appliance operations that occur during pretest ignition period. During the 15-minute 

period prior to the start of the test run, the wood heater loading door shall not be open 

more than a total of 1 minute. Coal bed raking is the only adjustment allowed during this 

period.

12.4.1.3 Coal Bed Weight. The appliance is to be loaded with the test fuel charge 

when the coal bed weight is between 10 percent and 20 percent of the test fuel charge 

weight. Coals may be raked as necessary to level the coal bed but may only be raked and 

stirred once between 15 to 20 minutes prior to the addition of the test fuel charge. 

12.4.1.4 Storage. The Category III and IV test runs may be done either with or 

without the thermal storage. If thermal storage is used the initial temperature of the 

storage must be 125°F or greater at the start of the test. The storage may be heated during 

the pre-test burn cycle or it may be heated by external means. If thermal storage is used, 

prior to the start of the test run, the storage tank destratification pump, shown in Figure 1, 

shall be operated until the total volume pumped exceeds 1.5 times the tank volume and 

the difference between the temperature at the top and bottom of the storage tank (TS1 and 
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TS2) is less than 1°F. These two temperatures shall then be recorded to determine the 

starting average tank temperature. The total volume pumped may be based on the 

nominal flow rate of the destratification pump (See section 9.6). If the Category III and 

IV runs are done with storage, it is recognized that during the last hour of the pre-burn 

cycle the storage tank must be mixed to achieve a uniform starting temperature and 

cannot receive heat from the boiler/heater during this time. During this time period the 

boiler/heater might cycle or go into a steady reduced output mode. (Note – this would 

happen, for example, in a Category IV run if the actual maximum output of the 

boiler/heater exceed the manufacturer’s rated output.) A second storage tank may be used 

temporarily to enable the boiler/heater to operate during this last hour of the pre-burn 

period as it will during the test period. The temperature of this second storage tank is not 

used in the calculations but the return water to the boiler/heater (after mixing device if 

used) must be 125°F or greater. 

12.4.2 Start-Up Procedure for Category I and II test runs, “cold-to-cold”. 

12.4.2.1 Initial Temperatures. This test shall be started with both the boiler/heater

and the storage at a minimum temperature of 125°F. The boiler/heater maximum 

temperature at the start of this test shall be 135°F. The boiler/heater and storage may be 

heated through a pre-burn or it may be heated by external means. 

12.4.2.2 Firebox Condition at Test Start. Prior to the start of this test remove all 

ash and charcoal from the combustion chamber(s). The loading of the test fuel and 

kindling should follow the manufacturer’s recommendations, subject to the following 

constraints: Up to 10 percent kindling and paper may be used which is in addition to the 
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fuel load. Further, up to 10 percent of the fuel load (i.e., included in the 10 lb/ft3) may be 

smaller than the main fuel. This startup fuel shall still be larger than 2”. 

12.4.2.3 Storage. The Category I and II test runs shall be done with thermal 

storage. The initial temperature of the storage must be 125°F or greater at the start of the 

test. The storage may be heated during the pre-test burn cycle or it may be heated by

external means. Prior to the start of the test run, the storage tank destratification pump, 

shown in Figure 1, shall be operated until the total volume pumped exceeds 1.5 times the 

tank volume and the difference between the temperature at the top and bottom of the 

storage tank (TS1 and TS2) is less than 1°F. These two temperatures shall then be 

recorded to determine the starting average tank temperature. The total volume pumped 

may be based on the nominal flow rate of the destratification pump (See section 9.6).

12.5 Test Runs. For all test runs, the return water temperature to the hydronic 

heater must be equal to or greater than 120°F (this is lower than the initial tank 

temperature to allow for any pipeline losses). Where the storage system is used, flow of 

water from the boiler/heater shall be divided between the storage tank and the heat 

exchanger such that the temperature change of the circulating water across the heat 

exchanger shall be 30 ± 5°F, averaged over the entire test run. This is typically adjusted 

using the system valves. 

Complete a test run in each heat output rate category, as follows: 

12.5.1 Test Run Start. For Category III and IV runs: once the appliance is 

operating normally and the pretest coal bed weight has reached the target value per 

12.4.1, tare the scale and load the full test charge into the appliance. Time for loading 
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shall not exceed 5 minutes. The actual weight of the test fuel charge shall be measured 

and recorded within 30 minutes prior to loading. Start all sampling systems. 

For Category I and II runs: once the appliance has reached the starting temperature, tare 

the scale and load the full test charge, including kindling into the appliance. The actual 

weight of the test fuel charge shall be measured and recorded within 30 minutes prior to 

loading. Light the fire following the manufacturer’s written normal startup procedure. 

Start all sampling systems. 

12.5.1.1 Record all water temperatures, differential water temperatures and water 

flow rates at time intervals of one minute or less. 

12.5.1.2 Record particulate emissions data per the requirements of EPA Method 

28 WHH and the standards referenced therein. 

12.5.1.3 Record data needed to determine Overall Efficiency (SLM) per the 

requirements of CSA B415.1-2010 Clauses 6.2.1, 6.2.2, 6.3, 8.5.7, 10.4.3 (a), 10.4.3(f),

and 13.7.9.3 

12.5.1.3.1 Measure and record the test room air temperature in accordance with 

the requirements of Clauses 6.2.1, 8.5.7 and 10.4.3 (g). 

12.5.1.3.2 Measure and record the flue gas temperature in accordance with the 

requirements of Clauses 6.2.2, 8.5.7 and 10.4.3 (f). 

12.5.1.3.3 Determine and record the Carbon Monoxide (CO) and Carbon Dioxide 

(CO2) concentrations in the flue gas in accordance with Clauses 6.3, 8.5.7 and 10.4.3 (i) 

and (j). 

12.5.1.3.4 Measure and record the test fuel weight per the requirements of Clauses 

8.5.7 and 10.4.3 (h). 
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12.5.1.3.5 Record the test run time per the requirements of Clause 10.4.3 (a). 

12.5.1.3.6 Record and document all settings and adjustments, if any, made to the 

boiler/heater as recommended/required by manufacturer’s instruction manual for 

different combustion conditions or heat loads. These may include temperature setpoints, 

under and over-fire air adjustment, or other adjustments that could be made by an 

operator to optimize or alter combustion. All such settings shall be included in the report 

for each test run. 

12.5.1.4 Monitor the average heat output rate on the load side of the heat 

exchanger based on water temperatures and flow. If the heat output rate over a 10 minute 

averaging period gets close to the upper or lower limit of the target range (± 5 percent), 

adjust the water flow through the heat exchanger to compensate. Make changes as 

infrequently as possible while maintaining the target heat output rate. The first test run 

shall be conducted at the category IV heat output rate to validate that the appliance is 

capable of producing the manufacturer’s rated heat output capacity. 

12.5.2 Test Fuel Charge Adjustment. It is acceptable to adjust the test fuel charge 

(i.e., reposition) once during a test run if more than 60 percent of the initial test fuel 

charge weight has been consumed and more than 10 minutes have elapsed without a 

measurable (1 lb or 0.5 kg ) weight change while the operating control is in the demand 

mode. The time used to make this adjustment shall be less than 60 seconds. 

12.5.3 Test Run Completion. For the Category III and IV, “hot-to-hot” test runs, 

the test run is completed when the remaining weight of the test fuel charge is 0.0 lb (0.0 

kg). (WFuelBurned = Wfuel) End the test run when the scale has indicated a test fuel charge 

weight of 0.0 lb (0.0 kg) or less for 30 seconds. 
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For the Category I and II “cold-to-cold” test runs, the test run is completed; and the end 

of a test is defined at the first occurrence of any one of the following: 

(a) The remaining weight of the test fuel charge is less than 1 percent of the total 

test fuel weight (WFuelBurned > 0.99 ∙ Wfuel);

(b) The automatic control system on the boiler/heater switches to an off mode. In 

this case the boiler/heater fan (if used) is typically stopped, and all air flow dampers are 

closed by the control system. Note that this off mode cannot be an “overheat” or 

emergency shutdown which typically requires a manual reset; or

(c) If the boiler/heater does not have an automatic off mode: After 90 percent of 

the fuel load has been consumed and the scale has indicated a rate of change of the test 

fuel charge of less than 1.0 lb/hr for a period of 10 minutes or longer. Note - this is not 

considered “stopped fuel combustion,” See section 12.5.6.1. 

12.5.3.1 At the end of the test run, stop the particulate sampling train and Overall 

Efficiency (SLM) measurements, and record the run time, and all final measurement 

values. 

12.5.3.2 At the end of the test run, continue to operate the storage tank 

destratification pump until the total volume pumped exceeds 1.5 times the tank volume. 

The maximum average of the top and bottom temperatures measured after this time may

be taken as the average tank temperature at the end of the tests (TFSavg, See section 

13.1). The total volume pumped may be based on the nominal flow rate of the 

destratification pump (See section 9.6). 

12.5.3.3 For the Category I and II test runs, there is a need to determine the 

energy content of the unburned fuel remaining in the chamber if the remaining mass in 
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the chamber is greater than 1 percent of the test fuel weight. Following the completion of 

the test, as soon as safely practical, this remaining fuel is removed from the chamber, 

separated from the remaining ash and weighed. This separation could be implemented 

with a slotted “scoop” or similar tool. A 1⁄4 inch opening size in the separation tool shall 

be used to separate the ash and charcoal. This separated char is assigned a heating value 

of 12,500 Btu/lb. 

12.5.4 Heat Output Capacity Validation. The first test run must produce a heat 

output rate that is within 10 percent of the manufacturer’s rated heat output capacity

(Category IV) throughout the test run and an average heat output rate within 5 percent of 

the manufacturer’s rated heat output capacity. If the appliance is not capable of producing 

a heat output within these limits, the manufacturer’s rated heat output capacity is 

considered not validated and testing is to be terminated. In such cases, the tests may be 

restarted using a lower heat output capacity if requested by the manufacturer. 

Alternatively, during the Category IV run, if the rated output cannot be maintained for a 

15 minute interval, the manufacturer may elect to reduce the rated output to match the 

test and complete the Category IV run on this basis. The target outputs for Cat I, II, and 

III shall then be recalculated based on this change in rated output capacity. 

12.5.5 Additional Test Runs. Using the Manufacturer’s Rated Heat Output 

Capacity as a basis, conduct a test for additional heat output categories as specified in 4.3. 

It is not required to run these tests in any particular order. 

12.5.6 Alternative Heat Output Rate for Category I. If an appliance cannot be 

operated in the Category I heat output range due to stopped combustion, two test runs 

shall be conducted at heat output rates within Category II. When this is the case, the 
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weightings for the weighted averages indicated in section 15.1.14 shall be the average of 

the Category I and II weighting’s and shall be applied to both Category II results.

Appliances that are not capable of operation within Category II (<25 percent of 

maximum) cannot be evaluated by this test method. 

12.5.6.1 Stopped Fuel Combustion. Evidence that an appliance cannot be operated 

at a Category I heat output rate due to stopped fuel combustion shall include 

documentation of two or more attempts to operate the appliance in heat output rate 

Category I and fuel combustion has stopped prior to complete consumption of the test 

fuel charge. Stopped fuel combustion is evidenced when an elapsed time of 60 minutes or 

more has occurred without a measurable (1 lb or 0.5 kg) weight change in the test fuel 

charge while the appliance operating control is in the demand mode. Report the evidence 

and the reasoning used to determine that a test in heat output rate Category I cannot be 

achieved. For example, two unsuccessful attempts to operate at an output rate of 10

percent of the rated output capacity are not sufficient evidence that heat output rate 

Category I cannot be achieved. 

12.5.7 Appliance Overheating. Appliances with their associated thermal storage 

shall be capable of operating in all heat output categories without overheating to be rated 

by this test method. Appliance overheating occurs when the rate of heat withdrawal from 

the appliance is lower than the rate of heat production when the unit control is in the idle 

mode. This condition results in the water in the appliance continuing to increase in 

temperature well above the upper limit setting of the operating control. Evidence of 

overheating includes: 1 hour or more of appliance water temperature increase above the 

upper temperature set-point of the operating control, exceeding the temperature limit of a 
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safety control device (independent from the operating control – typically requires manual 

reset), boiling water in a non-pressurized system or activation of a pressure or 

temperature relief valve in a pressurized system. 

12.5.8 Option to Eliminate Tests in Category II and III. Following successful 

completion of a test run in Category I, the manufacturer may eliminate the Cat II and III 

tests. For the purpose of calculating the annual averages for particulates and efficiency, 

the values obtained in the Category I run shall be assumed to apply also to Category II 

and Category III. It is envisioned that this option would be applicable to systems which 

have sufficient thermal storage such that the fuel load in the Cat I test can be completely 

consumed without the system reaching its upper operating temperature limit. In this case 

the boiler/heater would likely be operating at maximum thermal output during the entire 

test and this output rate may be higher than the Manufacturer’s Rated Heat Output 

Capacity. The Category II and III runs would then be the same as the Category I run. It 

may be assumed that the particulate emission values and efficiency values determined in 

the start-up, steady-state, and end phases of Category I are applicable in Categories II and 

III, for the purpose of determining the annual averages in lb/MMBtu and g/MJ (See 

section 13). For the annual average in g/hr, the length of time for stored heat to be drawn 

from thermal storage shall be determined for the test load requirements of the respective 

Category. 

12.5.9 Modification to Measurement Procedure in EPA Method 28 WHH to 

Determine Emissions Separately During the Startup, Steady-State and End Phases. With 

one of the two particulate sampling trains used, filter changes shall be made at the end of 

the startup phase and the steady state phase (See section 3.0). This shall be done to 
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determine the particulate emission rate and particulate emission index for the startup, 

steady state, and end phases individually. For this one train, the particulates measured 

during each of these three phases shall be added together to also determine the particulate 

emissions for the whole run. 

12.5.10 Modification to Measurement Procedure in EPA Method 28 WHH and 

the standards referenced therein on Averaging Period for Determination of Efficiency by

the Stack Loss Method. The methods currently defined in Method 28 WHH allow 

averaging over 10 minute time periods for flue gas temperature, flue gas CO2, and flue 

gas CO for the determination of the efficiency with the Stack Loss Method. However, 

under some cycling conditions the “on” period may be short relative to this 10 minute 

period. For this reason, during cycling operation the averaging period for these 

parameters may not be longer than the burner on period divided by 10. The averaging 

period need not be shorter than one minute. During the off period, under cycling 

operation, averaging periods as specified in EPA Method 28 WHH and the standards 

referenced therein may be used. Where short averaging times are used, however, the 

averaging period for fuel consumption may still be at 10 minutes. This average wood 

consumption rate shall be applied to all of the smaller time intervals included. 

12.6 Additional Test Runs. The testing laboratory may conduct more than one test 

run in each of the heat output categories specified in section 4.3. If more than one test run 

is conducted at a specified heat output rate, the results from at least two-thirds of the test 

runs in that heat output rate category shall be used in calculating the weighted average 

emission rate. The measurement data and results of all test runs shall be reported 

regardless of which values are used in calculating the weighted average emission rate. 
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13.0 Calculation of Results 

13.1 Nomenclature. 

COs – Carbon monoxide measured in the dilution tunnel at arbitrary time in ppm dry

basis. 

COg/min – Carbon monoxide emission rate in g/min. 

COT – Total carbon monoxide emission for the full test run in grams. 

CO_1 – Startup period carbon monoxide emissions in grams. 

CO_2 – Steady-state period carbon monoxide emission in grams. 

CO_3 – End period carbon monoxide emission in grams. 

ET – Total particulate emissions for the full test run as determined per EPA Method 28 

WHH and the standards referenced therein in grams. 

E1 = Startup period particulate emissions in grams. 

E2 = Steady-state period particulate emissions in grams. 

E3 = End period particulate emissions in grams. 

E1_g/kg = Startup period particulate emission index in grams per kg fuel. 

E2_g/kg = Steady-state period particulate emission index in grams per kg fuel. 

E3_g/kg = End period particulate emission index in grams per kg fuel. 

E1_g/hr = Startup period particulate emission rate in grams per hour. 

E2_g/hr = Steady-state period particulate emission rate in grams per hour. 

E3_g/hr = End period particulate emission rate in grams per hour. 

Eg/MJ – Emission rate in grams per MJ of heat output. 

Elb/mmBtu output – Emissions rate in pounds per million Btu’s of heat output. 

Eg/kg – Emissions factor in grams per kilogram of dry fuel burned. 
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Eg/hr – Emission factor in grams per hour. 

HHV – Higher Heating Value of fuel = 8600 Btu/lb (19.990 MJ/kg). 

LHV – Lower Heating Value of fuel = 7988 Btu/lb (18.567 MJ/kg). 

ΔT – Temperature difference between cooling water entering and exiting the heat 

exchanger. 

Qout − Total heat output in Btu’s (MJ). 

Qin − Total heat input available in test fuel charge in Btu’s (MJ). 

Qstd – Volumetric flow rate in dilution tunnel in dscfm. 

M − Mass flow rate of water in lb/min (kg/min). 

Vi – Volume of water indicated by a totalizing flow meter at the ith reading in gallons 

(liters). 

Vf – Volumetric flow rate of water in heat exchange system in gallons per minute 

(liters/min). 

Θ – Total length of burn period in hours (Θ1+ Θ2+ Θ3). 

Θ1 – Length of time of the startup period in hours. 

Θ2 – Length of time of the steady state period in hours. 

Θ3 – Length of time of the end period in hours. 

Θ4 – Length of time for stored heat to be used following a burn period in hours. 

ti − Data sampling interval in minutes. 

ηdel – Delivered heating efficiency in percent. 

Fi − Weighting factor for heat output category i. See Table 2. 

T1 – Temperature of water at the inlet on the supply side of the heat exchanger, °F. 

T2 – Temperature of the water at the outlet on the supply side of the heat exchanger, °F. 
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T3 – Temperature of cooling water at the inlet to the load side of the heat exchanger, °F. 

T4 – Temperature of cooling water at the outlet of the load side of the heat exchanger, °F. 

T5 – Temperature of the hot water supply as it leaves the boiler/heater, °F. 

T6 – Temperature of return water as it enters the boiler/heater, °F. 

T7 – Temperature in the boiler/heater optional destratification loop at the top of the 

boiler/heater, °F. 

T8 – Temperature in the boiler/heater optional destratification loop at the bottom of the 

boiler/heater, °F. 

TIavg − Average temperature of the appliance and water at start of the test. 

TIavg − (T5 + T6)/2 at the start of the test, °F. Eq. 1 

TFavg – Average temperature of the appliance and water at the end of the test. 

TFavg − (T5 + T6)/2 at the end of the test, °F. Eq. 2 

TIS1 − Temperature at the inlet to the storage system at the start of the test. 

TIS2 − Temperature at the outlet from the storage system at the start of the test. 

TFS1 − Temperature at the inlet to the storage system at the end of the test. 

TFS2 − Temperature at the outlet from the storage system at the end of the test. 

TISavg − Average temperature of the storage system at the start of the test. 

TISavg − (TIS1 + TIS2)/2 at the end of the test. Eq. 3 

TFSavg − Average temperature of the storage system at the end of the test. 

TFSavg − (TFS1 + TFS2)/2. Eq. 4 

MC – Fuel moisture content in percent dry basis. 

σ – Density of water in pounds per gallon. 
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σInitial – Density of water in the boiler/heater system at the start of the test in pounds per 

gallons. 

σboiler/heater – Density of water in the boiler/heater system at arbitrary time during the test 

in pounds per gallon. 

Cp – Specific heat of water in Btu /lb °-F. 

Csteel − Specific heat of steel (0.1 Btu/ lb -oF). 

Vboiler/heater – total volume of water in the boiler/heater system on the weight scale in 

gallons. 

Wfuel – Fuel charge weight, as-fired or “wet”, in pounds (kg). 

Wfuel_1 − Fuel consumed during the startup period in pounds (kg). 

Wfuel_2 – Fuel consumed during the steady state period in pounds (kg). 

Wfuel_3 – Fuel consumed during the end period in pounds (kg). 

WFuelBurned – Weight of fuel that has been burned from the start of the test to an arbitrary

time, including the needed correction for the change in density and weight of the water in 

the boiler/heater system on the scale in pounds (kg). 

WRemainingFuel – weight of unburned fuel separated from the ash at the end of a test. Useful 

only for Cat I and Cat II tests. 

Wapp − Weight of empty appliance in pounds (kg). 

Wwat – Weight of water in supply side of the system in pounds (kg). 

WScaleInitial – weight reading on the scale at the start of the test, just after the test load has 

been added in pounds (kg). 

WScale – Reading of the weight scale at arbitrary time during the test run in pounds (kg). 

WStorageTank − Weight of the storage tank empty in pounds (kg). 
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WWaterStorage − Weight of the water in the storage tank at TISavg in pounds (kg). 

13.2 After the test is completed, determine the particulate emissions ET in 

accordance with EPA Method 28 WHH and the standards referenced therein. 

13.3 Determination of the weight of fuel that has been burned at arbitrary time 

For the purpose of tracking the consumption of the test fuel load during a test run 

the following may be used to calculate the weight of fuel that burned since the start of the 

test: 

WFuelBurned = (WScaleInitial – WScale) + VBoiler/heater · (σInitial – σboiler/heater) Eq. 5

Water density, σ, is calculated using Equation 12. 

13.4 Determine Average Fuel Load Moisture Content. 

MC = ∑ WSliceWet_i – MCSlice_i Eq. 6

∑ WSliceWet_i

13.5 Determine heat input. 

Qin = (Wfuel/(1+(MC/100))) x HHV, Btu (MJ). Eq. 7 

Qin LHV = (Wfuel/(1+(MC/100))) x LHV, Btu (MJ). Eq. 8 

13.5.1 Correction to Qin for the Category I and II tests, where there is greater than 

1 percent of the test fuel charge in the chamber at the end of the test period. 

QInCorrected = Qin – WRemaining ∙ 12,500 Btu Eq. 9 

 lb 

13.6 Determine heat output, efficiency, and emissions 

13.6.1 Determine heat output as: 

Qout = Σ [Heat output determined for each sampling time interval] + Change in heat stored 

in the appliance + Change in heat in storage tank. 

Qout = Σ[Cpi ·Δ Ti· Mi· ti] + (Wapp · Csteel + Wwater · Cpa) ∙ (TFavg – TIavg) 

+ (WStorageTank · Csteel + WWaterStorage · Cpa) · (TFSavg – TISavg) Btu (MJ) Eq. 10
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Note: The subscript (i) indicates the parameter value for sampling time interval ti. 

Mi = Mass flow rate = gal/min x Density of Water (lb/gal) = lb/min. 

Mi=Vfi · σi, lb/min. Eq. 11 

σ i = (62.56 + ( -.0003413 x T3i ) + ( -.00006225 x T3i

2

)) 0.1337, lbs/gal. Eq. 12

Cp = 1.0014 + ( -.000003485 x T3i ) Btu/lb-oF. Eq. 13 

Csteel = 0.1 Btu/lb-oF. 

Cpa = 1.0014 + (-.000003485 X (TIavg +TFavg)/2), Btu/lb-oF. Eq. 14 

Vfi = (Vi –Vi-1)/(ti-ti-1), gal/min. Eq. 15 

Note: Vi is the total water volume at the end of interval i and Vi-1 is the total water 

volume at the beginning of the time interval. This calculation is necessary when a 

totalizing type water meter is used. 

13.6.2 Determine Heat Output Rate Over Burn Period (Θ1+ Θ2+ Θ3) as: 

Heat Output Rate = Qout/Θ, Btu/hr (MJ/hr). Eq. 16 

13.6.3 Determine Emission Rates and Emission Factors as: 

Eg/MJ = ET/(Qout x 0.001055), g/MJ. Eq. 17 

Elb/MM Btu output = (ET/453.59)/(Qout x 10-6), lb/MMBtu Out. Eq. 18 

Eg/kg = ET/(Wfuel/(1+MC/100)), g/dry kg. Eq. 19 

Eg/hr = ET/(Θ1+ Θ2+ Θ3+ Θ4), g/hr. Eq. 20 

Θ4= (WStorageTank · Csteel + WWaterStorage · Cpa) · (TFSavg – TISavg)/(Qout /Θ) Eq. 21

If thermal storage is not used in a Category III or IV run, then Θ4 = 0 

E1_g/kg = E1/(Wfuel_1/(1+MC/100)), g/dry kg 

E2_g/kg = E2/(Wfuel_2/(1+MC/100)), g/dry kg 

E3_g/kg = E3/(Wfuel_3/(1+MC/100)), g/dry kg 

E1_g/hr = E1/Θ1, g/hr 
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E2_g/hr = E2/Θ2, g/hr 

E3_g/hr = E3/Θ3, g/hr 

13.6.4 Determine delivered efficiency as: 

ηdel = (Qout/QInCorrected) x 100, %. Eq. 22 

ηdel LHV = (Qout/Qin LHV) x 100, %. Eq. 23 

13.6.5 Determine ηSLM - Overall Efficiency, also known as Stack Loss Efficiency, 

using Stack Loss Method (SLM). 

For determination of the average overall thermal efficiency (ηSLM) for the test run, 

use the data collected over the full test run and the calculations in accordance with CSA 

B415.1-2010, Clause 13.7 except for 13.7.2 (e), (f), (g), and (h), use the following 

average fuel properties for oak: %C = 50.0, %H = 6.6, %O = 43.2, %Ash = 0.2. 

13.6.5.1 Whenever the CSA B415.1-2010 overall efficiency is found to be lower 

than the overall efficiency based on load side measurements, as determined by Eq. 22 of 

this method, section 14.1.7 of the test report must include a discussion of the reasons for 

this result. For a test where the CSA B415.1-2010 overall efficiency SLM is less than 2 

percentage points lower than the overall efficiency based on load side measurements, the 

efficiency based on load side measurements shall be considered invalid. [Note on the 

rationale for the 2 percentage points limit. The SLM method does not include 

boiler/heater jacket losses and, for this reason, should provide an efficiency which is 

actually higher than the efficiency based on the energy input and output measurements or 

“delivered efficiency.” A delivered efficiency that is higher than the efficiency based on 

the SLM could be considered suspect. A delivered efficiency greater than 2 percentage 

points higher than the efficiency based on the SLM, then, clearly indicates a 

measurement error.] 
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13.6.6 Carbon Monoxide Emissions 

For each minute of the test period, the carbon monoxide emission rate shall be 

calculated as: 

COg/min = Qstd · COs · 3.298x10-5Eq. 24 

Total CO emissions for each of the three test periods (CO_1, CO_2, CO_3) shall be 

calculated as the sum of the emission rates for each of the 1 minute intervals. 

Total CO emission for the test run, COT, shall be calculated as the sum of CO_1, CO_2, 

and CO_3. 

13.7 Weighted Average Emissions and Efficiency. 

13.7.1 Determine the weighted average emission rate and delivered efficiency

from the individual tests in the specified heat output categories. The weighting factors 

(Fi) are derived from an analysis of ASHRAE Bin Data which provides details of normal 

building heating requirements in terms of percent of design capacity and time in a 

particular capacity range – or “bin” - over the course of a heating season. The values used 

in this method represent an average of data from several cities located in the northern 

United States.

Weighted average delivered efficiency: ηavg = Σ ηi x Fi, %. Eq. 25 

Weighted average emissions: Eavg = Σ Ei x Fi, % Eq. 26 

If, as discussed in section 12.5.8, the option to eliminate tests in Category II and 

III is elected, the values of efficiency and particulate emission rate as measured in 

Category I, shall be assigned also to Category II and III for the purpose of determining 

the annual averages. 

14.0 Report 

14.1.1 The report shall include the following: 
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14.1.2 Name and location of the laboratory conducting the test. 

14.1.3 A description of the appliance tested and its condition, date of receipt and 

dates of tests. 

14.1.4 A description of the minimum amount of external thermal storage that is 

required for use with this system. This shall be specified both in terms of volume in 

gallons and stored energy content in Btu with a storage temperature ranging from 125 °F 

to the manufacturer’s specified setpoint temperature. 

14.1.5. A statement that the test results apply only to the specific appliance tested. 

14.1.6 A statement that the test report shall not be reproduced except in full, 

without the written approval of the laboratory. 

14.1.7 A description of the test procedures and test equipment including a 

schematic or other drawing showing the location of all required test equipment. Also, a 

description of test fuel sourcing, handling and storage practices shall be included. 

14.1.8 Details of deviations from, additions to or exclusions from the test method, 

and their data quality implications on the test results (if any), as well as information on 

specific test conditions, such as environmental conditions. 

14.1.9 A list of participants and their roles and observers present for the tests. 

14.1.10 Data and drawings indicating the fire box size and location of the fuel 

charge. 

14.1.11 Drawings and calculations used to determine firebox volume. 

14.1.12 Information for each test run fuel charge including piece size, moisture 

content and weight. 
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14.1.13 All required data and applicable blanks for each test run shall be provided 

in spreadsheet format both in the printed report and in a computer file such that the data 

can be easily analyzed and calculations easily verified. Formulas used for all calculations 

shall be accessible for review. 

14.1.14 For each test run, Θ1,Θ2, Θ3, the total CO and particulate emission for 

each of these three periods, and Θ4. 

14.1.15 Calculated results for delivered efficiency at each heat output rate and the 

weighted average emissions reported as total emissions in grams, pounds per million Btu 

of delivered heat, grams per MJ of delivered heat, grams per kilogram of dry fuel and 

grams per hour. Results shall be reported for each heat output category and the weighted 

average. 

14.1.16 Tables 1A, 1B, 1C, 1D, 1E and 2 must be used for presentation of results 

in test reports. 

14.1.17 A statement of the estimated uncertainty of measurement of the emissions 

and efficiency test results. 

14.1.18 A plot of CO emission rate in grams/minute vs. time, based on 1 minute 

averages, for the entire test period, for each run. 

14.1.19 A plot of estimated boiler/heater energy release rate in Btu/hr based on 10 

minute averages, for the entire test period, for each run. This will be calculated from the 

fuel used, the wood heating value and moisture content, and the SLM efficiency during 

each 10 minute period. 

14.1.20 Raw data, calibration records, and other relevant documentation shall be 

retained by the laboratory for a minimum of 7 years. 
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15.0 Precision and Bias 

15.1 Precision − It is not possible to specify the precision of the procedure in this 

test method because the appliance operation and fueling protocols and the appliances 

themselves produce variable amounts of emissions and cannot be used to determine 

reproducibility or repeatability of this test method.

15.2 Bias − No definitive information can be presented on the bias of the 

procedure in this test method for measuring solid fuel burning hydronic heater emissions 

because no material having an accepted reference value is available. 

16.0 Keywords 

16.1 Solid fuel, hydronic heating appliances, wood-burning hydronic heaters, 

partial thermal storage. 
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Table 1A. Data Summary Part A 

Θ Wfuel MCave Qin Qout

Category

Run 

No

Load % 

Capacity

Target 

Load

Actual 

Load

Actual 

Load 

Test 

Duration

Wood 

Weight 

as-fired

Wood 

Moisture

Heat 

Input

Heat 

Output

Btu/hr Btu/

hr

% of 

max hrs lb %DB Btu Btu

I

< 15% of 

max

II

16-24% of 

max

III

25-50% of 

max

IV

Max 

capacity

Table 1B. Data Summary Part B 

T2 

Min ET E E Eg/hr Eg/kg ηdel ΗSLM

Category

Run 

No

Load % 

Capacity

Min 

Return

Water 

Temp.

Total PM 

Emissions

PM 

Output 

Based

PM 

Output 

Based

PM 

Rate

PM 

Factor

Delivered 

Efficiency

Stack 

Loss 

Efficiency

°F g

lb/MMB

tu Out g/MJ g/hr g/kg % %

I < 15% of 

max

II 16-24% 

of max

III 25-50% 

of max

IV Max 

capacity
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Table 1C. Data Summary Part C 

Θ1 Θ2 Θ3 CO_1 CO_2 CO_3 COT

Category

Run 

No

Load % 

Capacity

Startup 

Time. 

Steady 

State 

Time

End 

Time

Startup 

CO 

emission

Steady 

State CO 

emission

End CO 

emission

Total CO 

emission

min min min g g g g

I < 15% of 

max

II 16-24% of 

max

III 25-50% of 

max

IV Max 

capacity
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Table 1D. Data Summary Part D

E1 E2 E3 E1_g/kg E2_g/kg E3_g/kg

Category

Run 

No

Load % 

Capacity

Startup 

PM 

Steady 

State PM End PM

Startup 

PM 

emission 

index

Steady 

State PM 

emission

index

End PM 

emission 

index

g g g g/kg fuel g/kg fuel g/kg fuel 

I < 15% of 

max

II 16-24% of 

max

III 25-50% of 

max

IV Max 

capacity
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Table 1E: Hang Tag Information 

MANUFACTURER:

MODEL NUMBER:

ANNUAL EFFICIENCY RATING: ηavg (Using higher heating value)

(Using lower heating value)

PARTICLE EMISSIONS: Eavg GRAMS/HR (average)

LBS/MILLION Btu/hr OUTPUT

Table 2. Annual Weighting 

Category Weighting 

Factor (Fi)

ηdel,i x Fi Eg/MJ,i x Fi Eg/kg,i x Fi Elb/MMBtu Out,i x Fi Eg/hr,i x Fi

I 0.437

II 0.238

III 0.275

IV 0.050

Totals 1.000

Figure 1. Schematic of Equipment Test Setup
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Figure 2. Schematic of Test Equipment Set-up

Note: Illustrated appliance pump location and flow path through the appliance.

9. Part 60 is amended by revising Appendix I to read as follows:

Appendix I to Part 60—Owner's Manuals for Wood-Burning Heaters Subject to 

Subparts AAA, QQQQ, and RRRR of Part 60

1. Introduction

The purpose of this appendix is to provide specific instructions to manufacturers 

for compliance with the owner's manual provisions of subparts AAA, QQQQ, and RRRR 

of this part.

2. Instructions for Preparation of Wood Heater Owner's Manuals

2.1 Introduction
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Although the owner's manuals do not require premarket approval, EPA will 

monitor the contents to ensure that sufficient information is included to provide heater 

operation and maintenance information affecting emissions to consumers. The purpose of 

this section is to provide instructions to manufacturers for compliance with the owner's 

manual provisions of §60.536(f) of subpart AAA that applies to wood heaters, 

§60.5478(f) of subpart QQQQ that applies to hydronic heaters and forced-air furnaces, 

and §60.5490(g) of subpart RRRR that applies to masonry heaters. A checklist of topics 

and illustrative language is provided as instructions. Owner's manuals should be tailored 

to specific wood heater models, as appropriate.

2.2 Topics Required To Be Addressed in Owner's Manual

(a) Wood heater description and compliance status;

(b) Tamper warning;

(c) Catalyst information and warranty (if catalyst equipped);

(d) Fuel selection;

(e) Achieving and maintaining catalyst light-off (if catalyst equipped);

(f) Catalyst monitoring (if catalyst equipped);

(g) Troubleshooting catalytic equipped heaters (if catalyst equipped);

(h) Catalyst replacement (if catalyst equipped);

(i) Wood heater operation and maintenance; and

(j) Wood heater installation: achieving proper draft.

2.3 Sample Text/Descriptions

(a) The following are example texts and/or further descriptions illustrating the 

topics identified above. Although the regulation requires manufacturers to address (where 
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applicable) the ten topics identified above, the exact language is not specified. Manuals 

should be written specific to the model and design of the wood heater. The following 

instructions are composed of generic descriptions and texts. 

(b) If manufacturers choose to use the language provided in the example, the 

portion in italics should be revised as appropriate. Any manufacturer electing to use the 

EPA example language will be considered to be in compliance with owner's manual 

requirements provided that the particular language is printed in full with only such 

changes as are necessary to ensure accuracy. 

Example language is not provided for certain topics, since these areas are 

generally heater specific. For these topics, manufacturers should develop text that is 

specific to the operation and maintenance of their particular products.

2.3.1 Wood Heater Description and Compliance Status

Owner's Manuals must include:

(a) Manufacturer and model;

(b) Compliance status (exempt, 1990 std., 2015 std., etc.); and

(c) Heat output range.

Exhibit 1—Example Text covering (a), (b), and (c) above:

“This manual describes the installation and operation of the Brand X, Model 0 

catalytic equipped wood heater. This heater meets the U.S. Environmental Protection 

Agency's emission limits for wood heaters sold after January 1, 2014. Under specific test 

conditions this heater has been shown to deliver heat at rates ranging from 8,000 to 

35,000 Btu/hr.”

2.3.2 Tamper Warning
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The following statement must be included in the owner's manual for catalystequipped units:

“This wood heater contains a catalytic combustor, which needs periodic 

inspection and replacement for proper operation. It is against the law to operate this wood 

heater in a manner inconsistent with operating instructions in this manual, or if the 

catalytic element is deactivated or removed.”

2.3.3 Catalyst Information

The following information must be included with or supplied in the owner's and 

warranty manuals:

(a) Catalyst manufacturer and model;

(b) Catalyst warranty details; and

(c) Instructions for warranty claims.

Exhibit 2—Example Text covering (a), (b), and (c):

“The combustor supplied with this heater is a Brand Z, Long Life Combustor.

Consult the catalytic combustor warranty also supplied with this wood heater. Warranty 

claims should be addressed to:

Stove or Catalyst Manufacturer____________________

Address____________________

Phone #____________________”

2.3.3.1 This section should also provide clear instructions on how to exercise the 

warranty (how to package for return shipment, etc.).

2.3.4 Fuel Selection

Owner's manuals must include:
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(a) Instructions on acceptable fuels; and

(b) Warning against inappropriate fuels.

Exhibit 3—Example Text covering (a) and (b):

“This heater is designed to burn natural wood only. Higher efficiencies and lower 

emissions generally result when burning air dried seasoned hardwoods, as compared to 

softwoods or to green or freshly cut hardwoods.

DO NOT BURN:

• Treated Wood

• Coal

• Garbage

• Cardboard

• Solvents

• Colored Paper

• Trash

Burning treated wood, garbage, solvents, colored paper or trash may result in 

release of toxic fumes and may poison or render ineffective the catalytic combustor.

Burning coal, cardboard, or loose paper can produce soot, or large flakes of char or fly

ash that can coat the combustor, causing smoke spillage into the room, and rendering the 

combustor ineffective.”

2.3.5 Achieving and Maintaining Catalyst Light-Off

Owner's manuals must describe in detail proper procedures for:

(a) Operation of catalyst bypass (stove specific),

(b) Achieving catalyst light-off from a cold start, and
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(c) Achieving catalyst light-off when refueling.

2.3.5.1 No example text is supplied for describing operation of catalyst bypass 

mechanisms (Item (a) above) since these are typically stove-specific. Manufacturers must 

provide instructions specific to their model describing:

(1) Bypass position during start-up,

(2) Bypass position during normal operation, and

(3) Bypass position during reloading.

Exhibit 4—Example Text for Item (b):

“The temperature in the stove and the gases entering the combustor must be raised 

to between 500° to 700°F for catalytic activity to be initiated. During the start-up of a 

cold stove, a medium to high firing rate must be maintained for about 20 minutes. This 

ensures that the stove, catalyst, and fuel are all stabilized at proper operating 

temperatures. Even though it is possible to have gas temperatures reach 600°F within 2 to 

3 minutes after a fire is started, if the fire is allowed to die down immediately it may go 

out or the combustor may stop working. Once the combustor starts working, heat 

generated in it by burning the smoke will keep it working.”

Exhibit 5—Example Text for Item (c):

“REFUELING: During the refueling and rekindling of a cool fire, or a fire that 

has burned down to the charcoal phase, operate the stove at a medium to high firing rate 

for about 10 minutes to ensure that the catalyst reaches approximately 600°F.”

2.3.6 Catalyst Monitoring

Owner's manuals must include:
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(a) Recommendation to visually inspect combustor at least three times during the 

heating season;

(b) Discussion on expected combustor temperatures for monitor-equipped units;

and

(c) Suggested monitoring and inspection techniques.

Exhibit 6—Example Text covering (a), (b) and (c):

“It is important to periodically monitor the operation of the catalytic combustor to 

ensure that it is functioning properly and to determine when it needs to be replaced. A 

non-functioning combustor will result in a loss of heating efficiency, and an increase in 

creosote and emissions. Following is a list of items that should be checked on a periodic 

basis:

• Combustors should be visually inspected at least three times during the heating season 

to determine if physical degradation has occurred. Actual removal of the combustor is not 

recommended unless more detailed inspection is warranted because of decreased 

performance. If any of these conditions exists, refer to Catalyst Troubleshooting section 

of this owner's manual.

• This catalytic heater is equipped with a temperature probe to monitor catalyst operation. 

Properly functioning combustors typically maintain temperatures in excess of 500°F, and 

often reach temperatures in excess of 1,000°F. If catalyst temperatures are not in excess 

of 500°F, refer to Catalyst Troubleshooting section of this owner's manual.

• You can get an indication of whether the catalyst is working by comparing the amount 

of smoke leaving the chimney when the smoke is going through the combustor and 
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catalyst light-off has been achieved, to the amount of smoke leaving the chimney when 

the smoke is not routed through the combustor (bypass mode).

Step 1—Light stove in accordance with instructions in 3.3.5. 

Step 2—With smoke routed through the catalyst, go outside and observe the 

emissions leaving the chimney.

Step 3—Engage the bypass mechanism and again observe the emissions leaving 

the chimney.

Significantly more smoke should be seen when the exhaust is not routed through 

the combustor (bypass mode). Be careful not to confuse smoke with steam from wet 

wood.”

2.3.7 Catalyst Troubleshooting

The owner's manual must provide clear descriptions of symptoms and remedies to 

common combustor problems. It is recommended that photographs of catalyst peeling, 

plugging, thermal cracking, mechanical cracking, and masking be included in the manual 

to aid the consumer in identifying problems and to provide direction for corrective action.

2.3.8 Catalyst Replacement

The owner's manual must provide clear step-by-step instructions on how to 

remove and replace the catalytic combustor. The section should include diagrams and/or 

photographs.

2.3.9 Wood Heater Operation and Maintenance

Owner's manual must include:

(a) Recommendations about building and maintaining a fire;

(b) Instruction on proper use of air controls;
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(c) Ash removal and disposal;

(d) Instruction on gasket replacement; and

(e) Warning against overfiring.

2.3.9.1 No example text is supplied for (a), (b), and (d) since these items are 

model specific. Manufacturers should provide detailed instructions on building and 

maintaining a fire including selection of fuel pieces, fuel quantity, and stacking 

arrangement. Manufacturers should also provide instruction on proper air settings (both 

primary and secondary) for attaining minimum and maximum heat outputs and any

special instructions for operating thermostatic controls. Step-by-step instructions on 

inspection and replacement of gaskets should also be included. Manufacturers should 

provide diagrams and/or photographs to assist the consumer. Gasket type and size should 

be specified.

Exhibit 7—Example Text for Item (c):

“Whenever ashes get 3 to 4 inches deep in your firebox or ash pan, and when the

fire has burned down and cooled, remove excess ashes. Leave an ash bed approximately

1 inch deep on the firebox bottom to help maintain a hot charcoal bed.”

“Ashes should be placed in a metal container with a tight-fitting lid. The closed container 

of ashes should be placed on a noncombustible floor or on the ground, away from all 

combustible materials, pending final disposal. The ashes should be retained in the closed 

container until all cinders have thoroughly cooled.”

Exhibit 8—Example Text covering Item (e):

“DO NOT OVERFIRE THIS HEATER”
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“Attempts to achieve heat output rates that exceed heater design specifications 

can result in permanent damage to the heater and to the catalytic combustor if so 

equipped.”

2.3.10 Wood Heater Installation: Achieving Proper Draft

Owner's manual must include:

(a) Importance of proper draft;

(b) Conditions indicating inadequate draft; and

(c) Conditions indicating excessive draft.

Exhibit 9—Example Text for Item (a):

“Draft is the force which moves air from the appliance up through the chimney. 

The amount of draft in your chimney depends on the length of the chimney, local 

geography, nearby obstructions, and other factors. Too much draft may cause excessive 

temperatures in the appliance and may damage the catalytic combustor. Inadequate draft 

may cause backpuffing into the room and ‘plugging’ of the chimney or the catalyst.” 

Exhibit 10—Example Text for Item (b):

“Inadequate draft will cause the appliance to leak smoke into the room through 

appliance and chimney connector joints.”

Exhibit 11—Example Text for Item (c):

“An uncontrollable burn or a glowing red stove part or chimney connector 

indicates excessive draft.”
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Figure 1. Burn Wise Clean and Efficient Heating Checklist on the Back of the Label.