States take on the EPA in controversial wood stove proposal

Mary Uhl of WESTAR testifying at a
2018 air quality meeting.

Industry touts economic strain on stove retailers, but outdoor wood boiler and furnace manufacturers are also behind campaign for more time

Updated on June 17 - A virtual EPA hearing on June 8 pitted states against the EPA over emission limits from wood stoves, boilers and furnaces.  The EPA is proposing to ease the emissions compliance timeline for wood stoves and boilers but over a dozen states urged the EPA to withdraw its proposal.  Minnesota formally told the EPA and the wood heating industry that stoves and boilers must comply with the existing timeline that was set in 2015 for sales and shipments in their state.  California’s Air Resources Board took a more combative tone and said they are considering a lawsuit for the illegal sale of non-compliant stoves after May 15.

“Minnesota incorporated the 2015 NSPS and its 2020 timetable into state laws … which means that the May 15, 2020 compliance deadline is enforceable in Minnesota. EPA’s proposed revision will not change this deadline,” said Anne Jackson, an engineer with the Minnesota Pollution Control Agency in her written testimony.

Peter Solac, a long-time Minnesota
based stove retailer who may not be
able to take advantage of a federal
time extension 

Peter Solac, of Woodland Stoves and Fireplaces, is a stove retailer based in Minnesota who testified that he needed the additional time for 15 Step 1 stoves that he was not able to sell due to Covid-19.  He did not address the predicament that his state will not allow it.   Central Boiler may face an even greater problem, as its manufacturing facility is in Minnesota, and they apparently still had some Step 1 boilers they want to sell.  On June 17, Rodney Tollefson of Central Boiler said in an email that "we have almost zero inventory of 2015 level certified units.  We are not asking for a sell through for us.   Our testimony was requesting sell through for our dealers that have inventory."

US Stove has also indicated their interest to ship units from their manufacturing facility during the proposed sell-through.  On May 29, Brandon Barry of US Stove wrote that “our inventory levels are confidential. I will say that sell through would be beneficial for us at both the manufacturing and retail level.  Some product came back to our location and could be sold if sell through comes to fruition.” On June 10, Mr. Barry said that AGH had misunderstood his previous email that that “We have been buying product back from retail. All that does is hurt our cash flow, which ultimately impacts our ability to manufacture new 2020 products. We understand that this is a “retail” sell through under consideration and not a manufacturers sell through.”

List of registered speakers at the
June 8 EPA hearing

However, England Stove Works, another major value stove manufacturer that also had buy back agreements clearly said that they do not have inventory they need to sell during a sell-through but like many other stove manufacturers, they support the ability of their retailers to use a sell-through.  Other manufacturers who indicate that they do not have Step 1 inventory themselves include Blaze King, Empire, Hearthstone and SBI, but all support the sell-through for their retailers.  David Kuhfal, CEO of Hearthstone said, “Hearthstone proactively sold down all step 1 products however; we absolutely support the opportunity for our dealers to have some time to liquidate their Step 1 inventory.”  Hearth & Home Technology, the largest manufacturer of more expensive stoves, say that they have no Step 1 inventory and their retailers should have been able to clear out their Step 1 inventory on time as well.

AGH asked HPBA if they were also seeking a sell-through for manufacturers and received this reply from Emily McGee, their Communications Director: "the reason we didn't reply to your question was that we don't have a position on that specific issue (manufacturers selling Step 1 products during a potential sell-through). Our focus has been on the retailers and remains so."  Many retailers have gone further, saying that the sell-through should not be open to manufactuers.

Of the 17 people who testified, about half were in favor of the sell-through and half were against it.  As with previous hearings and written testimony on the EPA wood heater regulations, all states and regional air agencies representing states were against extending deadlines.  Several retailers, a distributor, two manufacturers and HPBA representatives testified in favor of it.  Three non-profits were represented with the American Lung Association and EarthJustice speaking against, and the Alliance for Green Heat who favored a limited sell-through.  AGH is urging the EPA to only allow the sell-through for retailers, not manufacturers and also to limit it to stoves, not to central heaters.  Manufacturers of central heaters have been at the forefront of the fight for extended deadlines and sell-through and pose the largest threat to increased air pollution.

John Crouch, in upper left, in Crested
Butte, CO in 1989 with Bob Ferguson.

The arguments made by both sides were relatively predictable, with very little common ground.  However, Roger Ayers of Dreamstyle Remodeling focused on the need to regulate fireplaces that he estimates emit 44 grams of particulates per hour. Why focus on the difference of a gram or two between Step 1 and Step 2 when any home can still install unregulated fireplaces.  John Crouch of HPBA reminded everyone that many Step 1 stoves were already under 3.5 grams an hour and “the EPA has done no in-home testing of Step 1 or Step 2 stoves and has no way of knowing if these Step 2 stoves are an improvement or not.” 

Industry has asserted that there should have been a sell-through period built into the timeline from the start, like there was in 1988.  Mary Uhl of WESTAR countered that contention in her testimony, saying “In contrast to the original 1988 NSPS, in which manufacturers and retailers were allowed only two years to transition to more stringent standards, they received five years in the 2015 NSPS update.” 

Most of the states and air agencies argued that the EPA lacked a legal basis for the proposal,  did not do any regulatory impact analysis and is proposing to substitute two of the worst sales months for two of the best.  Maria Smilde of EarthJustice closed her testimony saying “Considering that respiratory difficulties have been a common COVID-19 symptom, the EPA should not use one public health crisis to rationalize extending another, nor does the Clean Air Act permit it to do so.”  Anne Jackson made a similar point, arguing that, “Given the health burden of fine particulate matter, there is no good reason to provide additional time to sell noncompliant devices, especially hydronic heaters, in the face of fighting a deadly, respiratory virus pandemic.”

Possibly the most surprising arguments against the sell-through came from the Minnesota Pollution Control Agency. “Minnesota was expecting full support from EPA to notify manufacturers and retailers about the approaching May 2020 deadline, and to undertake enforcement as necessary, especially with internet sales, as that is the most difficult for Minnesota to monitor. With EPA’s announcement of a proposed sell-through period along with lax enforcement, Minnesota must now undertake a nation-wide communication effort to notify manufacturers and retailers that Minnesota law does not allow sales in Minnesota of non-Step 2 wood-burning appliances.“

California is an anomaly as stationary sources of pollution are controlled by local air districts, not by the state.  Their Air Resources Board commented “Many states, and over half of California’s 35 local air districts, including the largest air districts, have delegated EPA authority to enforce the NSPS.  Under Clean Air Act section 304, states, other jurisdictions, and private citizens can also file citizen suits for sale of Step 1 stoves before any sell-through is finalized.  EPA may have chosen not to enforce the Step 1 sales ban in the period before any sell-through is finalized, but others can.”

The EPA will be transcribing all the testimony from the hearing and entering it into the official record, as they consider whether to approve a sell-through. 

Related stories

EPA and states vigorously defend wood stove audit testing (Sept. 2020)

AGH testimony on EPA's proposed sell-through for wood boilers and furnaces

On November 21, 2018, EPA proposed amendments to the New Source Performance Standards (NSPS) for Residential Wood Heaters issued in 2015. The proposed amendments would allow retailers an additional 2 years to sell the existing inventory of hydronic heaters and forced-air furnaces. EPA is also taking comment on a similar sell-through provision for wood stoves and on whether the pellet fuel requirements should be revised.  This is the statement delivered by John Ackerly, the President of the Alliance for Green Heat at the EPA hearing held on December 17, 2018.

Via Public Hearing

U.S. Environmental Protection Agency  

EPA WJC East Building

Room 1117A&B

1201 Pennsylvania Avenue NW

Washington, DC 20460

Attn:              Docket ID No. EPA-HQ-OAR-2018-0195

Re:                  Statement of the Alliance for Green Heat in response to EPA’s Proposed Standards of Performance for New Residential Wood Heaters, New Residential Hydronic Heaters and Forced-Air Furnaces, 83. Fed. Reg. 61,574 (Nov. 30, 2018).

Thank you for the opportunity to testify here today.  My name is John Ackerly and I am the President of the Alliance for Green Heat. We promote modern wood and pellet heating systems as a low-carbon, renewable and affordable energy solution. We just hosted the 4^thWood Stove Design Challenge, highlighting R& D and innovation in the sector.  This industry has a lot to be proud of and some of people in the room today make some of the cleanest wood and pellet stoves in the country, enabling consumers to substantially reduce fossil fuel usage.  This is a critical juncture for the EPA with regard to residential wood heaters and there is a lot at stake with regard to air quality, energy and human health.

The Alliance for Green Heat strongly opposes the proposed amendmentsthat would allow manufacturers to sell Step 1 hydronic heaters and forced-air furnaces right up to May 2020 and retailers an additional 2 years to sell them.

I want to start by saying that this sell-through is a waste of EPA’s resources.  The agency has far more important things to consider, such as addressing how we transition to testing with cordwood.  The EPA does not have endless time and resources to regulate wood and pellet heating. Please spend EPA’s valuable resources on issues that will advance our industry and improve efficiencies, not prolong the old technology that threatens the health of rural communities.

Second, it is very surprising that the EPA would consider relief for outdoor wood boilers, hydronic heaters and furnaces.  Most of these heaters are the biggest source of the air quality problems from this industry.  Given the high levels of emissions from these units, they give a bad name to all the cleaner types of wood and pellet heating appliances currently available to consumers.  EPA should not reward a small part of the industry that has not invested in technology to improve performance and emissions of its heaters.  Tens of thousands of low-income and rural communities could be stuck with these higher polluting units for decades to come if EPA finalizes a sell-through.  

Third, EPA’s preamble says that the agency is proposing a sell-through because “it is reasonable to assume that retailers may become increasingly reluctant to purchase non-Step 2-compliant wood heating devices.”  But isn’t that the desired outcome? Improving air quality and human health by increasing the efficiency of the residential wood heater sector is a principal goal of the original regulation.  It is the intended result of the regulation to move retailers to focus inventory on Step 2-compliant devices.  There is evidence that some retailers would likely switch to manufacturers that are producing 2020 compliant models.

Lamppa Manufacturing is one such manufacturer.  Lamppa is a smaller manufacturer, and they are looking to connect with retailers.  Their unit is very affordable at a retail price of $5,295 and is compliant with the 2020 Phase 2 standard. Tarm Biomass, who makes 2020 compliant wood and pellet boilers is getting calls from dealers looking for 2020 product.  So are others who have 2020 compliant units. . Competition in the marketplace is fundamental to consumers having access to more efficient and cleaner burning appliances. This proposal works against these market forces, and in effect subsidizes the worst performing technologies.

Step 2 compliant Lamppa furnaces
being built

We all know that this isn’t just to help retailers sell stranded inventory.  After all, who are the retailers?  Some of them are Home Depot, Tractor Supply, Northern Tool and other chains that need no help. Increasingly, retailers are on E-bay and it’s hard to even tell who they are, much less monitor compliance. And a big problem is that many manufacturers want to keep selling these Step 1 units  and never intend to do the R&D to become Step 2 compliant.  Giving them 2 more years just undercuts those who have the ability to meet Step 2. 

It is important for the agency and all stakeholders to reflect on the impact of Step 1 units on air quality and energy use.  One such unit made by US Stove Company is rated as only 33% efficient, yet the EPA says that their “proposed actions are anticipated to have negligible impacts on energy costs or usage.” In fact, there is clear evidence that cleaner, more advanced units will lower energy costs by decreasing overall energy use and improve air quality.

Units made by US Stove are often improperly or illegally advertised by their dealers, like this one that says it can be used with wood or coal. (Dec. 13, 2018 screen shot)

Fourth, EPA should work to improve compliance of a sector that, at times, has been reluctant to change and at times, simply ignores regulations.  Currently, there are thousands of illegal, newly manufactured uncertified new outdoor wood boiler and furnaces being openly sold around the country.  A recent conversation with a manufacturer in the Midwest claiming it offers “the highest quality outdoor furnace available on the market” even though the manufacturer has no certified units and openly sells non-Step 1 units.  The manufacturer said that EPA’s laws and regulations may not apply in Missouri, and that the regulations may have already been overturned.  This manufacturer has 81 dealers in 21 states and no indication anywhere on their website that wood furnaces and boilers need certification. Even more concerning is that EPA’s compliance office indicated that the agency has no record of the manufacturer’s existence or continued operation.  Many smaller companies also continue to sell and advertise uncertified outdoor wood boilers. 

An uncertified Acme wood furnace currently on the market. (Dec. 13, 2018 screen shot)

The Alliance is concerned that establishing a 2-year sell-through would add another layer of work and complexity to a regulation that has already shown serious enforcement challenges.

Finally, by providing a last-minute sell through, EPA is moving the “goal posts” in the middle of the game.  Manufacturers and retailers require regulatory certainty to make business decisions that make the sector more efficient, cleaner, and safer. Putting those companies that took the EPA deadlines seriously and invested in cleaner technology at a competitive disadvantage is simply bad policy.    

Companies have shown that best available technology is available and affordable.  We need an EPA to craft a regulatory framework that supports efforts to modernize the sector and then stick to it.  Do not approve this proposal.

Opinions of top wood stove industry insiders revealed in 1998 interviews

The late Paul Tiegs, one of the
greatest authorities on wood
stoves, conducted the
interviews for the EPA. 

Long before the regulatory debate about wood stoves heated up in the 2010s, the EPA commissioned a series of fascinating interviews with the top wood stove experts in the country on a host of technical and policy issues.  These interviews give a glimpse of the opinions and philosophies of industry and academic leaders at a time when they apparently felt free to go on the record about what became controversial topics. 

The content of these interviews remains very relevant today for anyone interested in a behind-the-scenes look at many of the underlying issues in the 2015 EPA stove and boiler regulations.  The interviewers – Jim Houck and Paul Teigs (who are top experts themselves) – asked questions ranging from whether masonry, pellet, boiler and furnace appliances should be regulated, to the vulnerabilities of catalytic stoves, to how lab testing can better reflect real world use of stoves. 

These interviews remain a valuable resource because each of the nine experts was asked the exact same questions.  Thus, if you are interested in masonry heaters, or catalytic or pellet stoves, or how labs coax the best numbers from stoves, it is relatively easy to scroll down and see how each person answered the question.  Of the nine interviewees, four are from industry (John Crouch, Bob Ferguson, Dan Henry and Michael Van Buren), two from test labs (Rick Curkeet and Ben Myren), two from academia (Skip Hayden and Dennis Jaasma) and one from EPA (Robert C. McCrillis). Their full titles and affiliations are at the end of this blog along with the full list of questions asked.  The full set of questions and answers are in Appendix B on page 58 and can be downloaded here (pdf).

In general, Bob Ferguson and Dan Henry tended to oppose further regulation, and felt, for example, that pellet stoves and wood-fired central heating appliances did not need to be regulated.  Ben Myren tended to favor a blanket approach of closing loopholes and regulating all appliances.  This difference in views between two industry experts and one test lab expert can be viewed through their respective economic interests and how it would affect their livelihoods.  But these interviews also show deeper philosophical differences and illuminate the reasons for their positions, whether they concern the health impacts of wood smoke, consumer protection, profitability, practicality of test method changes, etc.

We have chosen to reproduce the answers to two questions and invite readers to refer to the full set of interviews to find issues that they may be more interested in, such as the impact of wood species on emissions, stress testing to see how durable stoves are, and options to promote or require education or maintenance of stoves by consumers. 

When the Alliance for Green Heat began ten years after these interviews in 2009, much of the content had already been seemingly lost or obscured.  Very few people, for example, knew of the origin or impact of the 35:1 air-to-fuel ratio loophole that allowed pellet stove manufacturers to make low efficiency stoves in order to avoid regulation.  Right up until 2014, state and federal government agencies, along with top industry outlets, continued to propagate myths about pellet stoves.  Even the EPA never advised consumers that uncertified pellet stoves were likely to have lower efficiencies due to the 35:1 loophole they created.  These interviews provide the best information anywhere on how this came to be and what impact it had on the pellet stove industry and consumers.

We chose the question about whether central heaters should be regulated because this turned into one of the biggest issues in the 2015 regulations.  Only one interviewee – John Crouch – saw a causal relationship between the rise of outdoor wood boilers and the 1988 emissions regulations. 

Question: The 35:1 air-to-fuel ratio cut-off for certification has produced two classes of pellet stoves — those that are certified and those that are not. The latter class may have models that are less efficient and have higher emissions than the former. Should the regulations be amended to close the loop-hole and discourage the practice of intentionally designing models with a higher air-to-fuel ratio to avoid certification?

John Crouch, HPBA's
foremost wood stove expert.

John Crouch, HPBA: I wouldn’t use the term “close the loop-hole”. I would say, “is the proper place to cut off the definition of a wood heater?” We all know the whole discussion during the Reg-Neg ignored this emerging category of pellet stoves. So this gets back into my other broader comment, which is, instead of going back in and changing the NSPS in a piecemeal fashion, there needs to be a true revision of the whole thing that deals with the category of pellets and masonry heaters and outdoor furnaces.

Rick Curkeet, Intertek: Yes. The way to amend the regulation is to simply remove the 35:1 air/fuel ratio exemption. This has never been required by fireplaces (they meet the 5 kg/hr minimum burn rate exemption criterion anyway). Pellet units are readily able to meet emissions requirements and the exemption only encourages making these units less efficient to avoid the regulation.

Bob Ferguson, Consultant: The 35:1 cutoff was intended for fireplaces. However, pellet stoves are the only product that even take advantage of the air-fuel exemptions. Fireplaces generally use the burn rate exemption. Pellet stoves probably don’t need to be regulated at all. They are all quite clean burning. Let the marketplace decide if exempt stoves are acceptable. If pellet stove users demand products that use fewer pellets (more efficient), the manufacturers will respond. 

Skip Hayden, Researcher: Yes. In Canada, we recommend that people buy only EPA-approved pellet stoves. We have developed a high ash pellet stove that's operating around 85% and its emissions are about 0.3 g/hr or less. 

Dan Henry, a founder of Quadrafire
stoves is one of industry's most
articulate spokesmen.

Dan Henry, Aladdin: There is no data that indicates that even a poorly operating stove is a dirty burning appliance. They are inherently clean, becoming more and more reliable, and don’t fix them if they aren’t broken.

Dennis Jaasma, University of VA: Pellet stoves are inherently clean burning unless there is something very bad about their design. I am not concerned about regulating the currently uncertified units unless their field emissions are bad compared to certified stoves.

Robert C. McCrillis, EPA: Yes, all pellet stoves should be affected facilities and not subjected to that 35:1.

Ben Myren one of Amreica's most
thoughtful and experienced stove tester.

Ben Myren, Myren Labs:  I agree, no more loop-holes. The new technology stoves that are coming on the market are going to be totally new critters. I don’t think that turning down the air- to-fuel ratio, to make it whatever it is, should get you out of the loop. Some of those suckers have got to be just filthy. I mean you look at the flame. I’ve seen them burn at the trade show; you know, the glass is sooting up on the edges. You can just see it.

Michael van Buren was a technical
expert with The Hearth Products
Association, now HPBA

Michael Van Buren, HPBA: I don’t know what that loop-hole does, whether it really affects the operation of the stove and the efficiency of the stove.

Question: According to a Department of Energy survey out of the 20.4 million households that used a wood burning appliance in 1993, less than 0.3 million used a wood burning furnace as their primary source of heat. Are there enough wood-fired central heating furnaces in use to merit their closer evaluation? How many commercially available models are there? Are there emissions data for them? Should they be certified?

John Crouch: The [1988] EPA New Source Performance Standards killed the indoor furnace industry and created this little loop-hole which the outdoor furnace industry is beginning to exploit and kind of underscores the need for a more comprehensive wood burning regulation which sets out over a several year period to codify all forms of wood burning technology.

Rick Curkeet tested stoves for Intertek
labs and is one of industry's top experts.

Rick Curkeet: I don’t know how many new units are being produced but I’m sure it’s a very small number. Still, one really poor unit can be a significant problem if it’s in your neighborhood. There have never been any standards for testing this type of product for emissions and efficiency. However, we have adapted existing methods and can say that the performance range is very wide. Poor designs may be 30% or less efficient and produce nearly 100 grams/hr emissions rates. Good designs are able to approach certified wood stove performance levels.

Bob Ferguson: I don’t feel there are enough units being sold to merit any activity what-so-ever. There are only a handful of manufacturers. I don’t think there has been anything published--so if testing has been conducted, it is probably a good assumption that the numbers aren’t that good. They shouldn’t be certified, as you would have to develop test methods and standards. The country would be better off using the money to pay manufacturers to phase out of production, sort of like the agricultural method of paying farmers not to grow certain crops.

The late Skip Hayden also worked
at the US Federal Enercan Lab,
back when the federal government
focused more on wood heating.

Skip Hayden: The number of central wood furnaces in Canada, certainly in comparison to the United States, would be higher. In our Eastern provinces, it’s a relatively common add-on to existing oil furnaces. Generally, they are as dirty as can be.

Dan Henry: I think a lot of these are used in rural areas and considering the fuels that are out there, I don’t think they should be regulated. Maybe just a spot check of some sort. I think the only thing that would benefit would be the testing laboratories. If it emits particulate into an air shed where it can have an adverse effect on the industry (my ability to make a living), then yes.

Dennis Jaasma
also ran a combustion
 research lab at
Virginia Polytechnic
 Institute.

Dennis Jaasma: Yes, central heaters merit further evaluation. I don't know how many models are available. I think EPA has done some work on them, but I do not know any results. Yes, they should be certified. They are in danger of becoming extinct if they don't wind up with a certification program.

Robert C. McCrillis: In some localities I think these furnaces are a problem; I don’t know how many are commercially available. I think I can name off six or eight companies and each one makes several models, but I don’t know what the total market is, maybe 10,000 - 15,000 a year. The little bit of testing that we did here, says that they are probably on a par with a conventional wood stove. The way those things work, they have a thermostatically operated draft and when the thermostat shuts off the draft closes, so you get this real smoldering burning situation. Secondary combustion technology probably wouldn’t work. Possibly a catalytic technology would, but I just don’t think it stays hot enough in there. I guess that really depends on the impact.

Ben Myren: I don’t think they should be exempt for any reason. As to the rest of it--are there emissions data for them? I suspect there are. Should they be certified? Yes they should be certified. Nobody should be exempt from the process.

Michael van Buren: I think there should be some type of testing on them.

List of Experts Interviewed

Mr. John Crouch, Director of Local Government Relations, Hearth Products Association (CA) [now HPBA]

Mr. Rick Curkeet, P.E., Manager, Intertek Testing Services (IL)

Mr. Bob Ferguson, President, Ferguson, Andors and Company (VT)

Dr. Skip Hayden, Director, Combustion and Carbonization Research Laboratory (Ontario, Canada)

Mr. Daniel Henry, Vice President, Aladdin Steel Products, Inc. (WA) [now Quadrafire]

Dr. Dennis Jaasma, Associate Professor, Department of Mechanical Engineering, Virginia Polytechnic Institute and State University (VA)

Mr. Robert C. McCrillis, P.E., Mechanical Engineer, Air Pollution Prevention and Control, Division, U.S. EPA (VA)

Mr. Ben Myren, President, Myren Consulting (WA)

Mr. Michael Van Buren, Technical Director, Hearth Products Association (VA) [now HPBA]

Interview Questions

RWC Technology Review

Environmental Protection Agency Order no. 7C-R285-NASX

prepared by

OMNI Environmental Services, Inc.

Beaverton Oregon 97005

1. State-of-the-art of wood stove combustion and emission control technologies.

1. 1.1  Are in-home emission reductions as compared to conventional stoves shown in Table 1 for catalytic and non-catalytic certified stoves reasonable?
2. 1.2  Are efficiencies shown in Table 2 for catalytic and non-catalytic certified stoves reasonable?
3. 1.3  Can catalytic technology for use in wood stoves be fundamentally improved?
4. 1.4  Is the use of manufactured fuel (densified and wax logs) a credible emission

reduction strategy? See Tables 1 & 2 .

5. 1.5  For non-catalytic stoves the heat retention adjustment with refractory material of various densities can reduce particulate emissions. How big an effect can this have?
6. 1.6  Approximately one half of the particulate emissions occur during the kindling phase for non-catalytic wood stoves and more than half for catalytic wood stoves. Are there improvements in technology that can mitigate this problem? Can specially designed high BTU wax logs be used to achieve a fast start and reduce kindling phase emissions?
7. 1.7  Should masonry heaters with tight fitting doors and draft control be classified as a wood stove and be subject to some type of certification even though most weigh more than 800 kg?
8. 1.8  Are the emissions and efficiencies for masonry heaters, based on in-home tests, shown in Tables 1 and 2 reasonable?

9. 1.9  The OMNI staff feels the emissions per unit of heat delivered (e.g., lb/MBTU or g/MJ) is a more appropriate way to rank the performance of wood burning appliances than emission factors (lb/ton or g/kg) or emission rates (g/hr). — Comments?
10. 1.10  Default efficiency values are used for wood stoves. This coupled with the fact that emission factors or rates (not g/MJ) are used to rank wood stoves does not provide an incentive for manufacturers to increase the efficiency of their stoves. — Comments? Should an efficiency test method as described (FR v. 55, n 161, p. 33925, Aug. 20,1990) be required to be used and the results listed?
11. 1.11  Have certified stove design and performance improved since the first certified stoves? If so, how?

2. State-of-the-art of fireplace emission control technology.
1. 2.1  Are the emission factors and efficiencies for the in-home use of fireplaces and inserts shown in Tables 3 and 4 reasonable?
2. 2.2  There appear to be only a few practical design or technology options for fireplaces that will potentially mitigate particulate emissions. — What designs and technologies are available? What retrofit options are there?
3. 2.3  The use of wax fire logs reduces emissions over the use of cordwood. Can the formulation of wax logs be changed to produce even less emissions?
4. 2.4  What are the distinctions between a masonry fireplace and a masonry heater?
5. 2.5  As with wood stoves, the OMNI staff believe that the mass of emissions per unit of heat delivered is a better way to rank the performance of fireplaces than emission factors or emission rates.
3. State-of-the-art of wood-fired central heating furnace emission control technology.

3.1 According to a Department of Energy survey out of the 20.4 million households that used a wood burning appliance in 1993, less than 0.3 million used a wood burning furnace as their primary source of heat. Are there enough wood-fired central heating furnaces in use to merit their closer evaluation? How many commercially available models are there? Are there emissions data for them? Should they be certified?

4. State-of-the-art of pellet-fired wood stove technology.

1. 4.1  Are the emissions and efficiencies for the in-home use of pellet stoves shown in Tables 1 and 2 reasonable?
2. 4.2  The 35:1 air-to-fuel ratio cut-off for certification has produced two classes of pellet stoves — those that are certified and those that are not. The latter class may have models that are less efficient and have higher emissions than the former. Should the regulations be amended to close the loop-hole and discourage the practice of intentionally designing models with a higher air-to-fuel ratio to avoid certification?
3. 4.3  Have pellet stove design and performance improved since the first models were introduced? If so, how?

1. Ramifications of ISO.

5.1 The International Organization for Standardization (ISO) has a technical committee for developing emissions, efficiency and safety test standards for wood-fired residential heaters and fireplaces. (See Table 5 for comparison of the draft ISO method 13336 with EPA methods 28, 5G and 5H.) Do you feel that the EPA methods should be replaced with or be made comparable to an international standard?

2. Correspondence between in-home and laboratory emission test results.
1. 6.1  How accurately do certification tests predict in-home performance?
2. 6.2  How would you design research testing in the laboratory to simulate in-home use?
3. EPA Method 28 strengths and weaknesses.
1. 7.1  Method 28 is in part an “art”. Fuel loading density, fuel moisture, fuel characteristics (old vs new growth, grain spacing, wood density) and coal bed conditioning can be adjusted within the specification range of the method to influence results. In your experience what things have the most effect on particulate emissions? How much influence can they have?
2. 7.2  Burn rate weighting is based on very limited data and the cities from where the data were obtained are not very representative of wood use nationwide (see Table 6). How can the weighting scheme be improved to be more representative of the nation as a whole?
3. 7.3  The equation for the calculation of the air-to-fuel ratio as in Method 28A is in error. The error produces a small but significant difference in the calculated air-to-fuel ratio. Should the method be corrected or should it be left as a “predictor” of the air-to-fuel ratio?

7.4 The assumed mole fraction of hydrocarbons (YHC) is defined as a constant in the air-to-fuel ratio calculations in Method 28A. The mole fraction of hydrocarbons in the vapor phase will vary significantly with fuel and combustion conditions. Should hydrocarbon vapors (more appropriately, organic compound vapors) be measured as part of the method?

4. EPA Methods 5G and 5H correlations.

8.1 The comparison data to demonstrate the correlation between 5G and 5H are limited. Should the correlation between the two methods be reevaluated?

5. Performance deterioration of EPA-certified wood stoves in the field.
1. 9.1  It is the opinion of many in the wood stove industry that catalysts last only five years and that a stove designed for a catalyst operated without a functioning catalyst can produce as much emissions as a conventional stove. — Comments?
2. 9.2  Field studies in Glens Falls, NY, Medford, OR, Klamath Falls, OR and Crested Butte, CO showed that emissions from some catalytic stoves became appreciably worse even after two to three years of use. Inspection of stoves in Glens Falls showed that catalyst deterioration and leaky bypass systems were responsible. Have improvements been made in the design of catalytic stoves to minimize these problems? Is it reasonable to require homeowner training on the proper use of catalytic stoves and/or to incorporate into their costs an inspection and catalyst replacement program?
6. Stress test pros and cons.
1. 10.1  A short-term laboratory woodstove durability testing protocol was developed to predict the long-term durability of stoves under conditions characteristic of in- home use (see EPA-600/R-94-193). It was concluded in that study that damage occurs during those occasional times when a woodstove is operated in the home at exceptionally high temperatures. The laboratory stress test was designed to operate a woodstove at very high temperatures over a one to two week period to predict long-term durability under in-home use. Is this a reasonable approach?
2. 10.2  Should a stress test be made part of the certification process?
7. Feasibility of developing separate emission factors for dry and wet wood and for

softwood and hardwood species classes.

1. 11.1  Optimum wood moisture for low particulate emissions seems to be in the 18% to 20% range. Are you aware of any data that will allow the impact of wood moisture to be isolated from other variables? Could it be different for wood from different tree species?
2. 11.2  Wood from different tree species clearly burns differently. The chemical make-up and density of wood from different tree species is different. For example wood from coniferous trees has more resin than wood from deciduous trees. It is believed that particulate emission factors will be different for wood from different tree species. If this is true different parts of the country may have different emissions factors for residential wood combustion. Are you aware of any data that document different emission factors for wood from different tree species?

8. Routine maintenance.

12.1 Would routine maintenance of stoves once they were in a home reduce particulate emissions? Would this be more relevant for catalytic stoves than non-catalytic stoves? Would this be relevant for pellet stoves with electronic and moving parts?

2. 12.2  Should the home owner be provided with a maintenance manual or a training course at the time of purchase? Should a maintenance program be part of the purchase price particularly for catalytic stoves?
3. 12.3  What would the key elements of routine maintenance be?

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