AGH urges the IRS to issue guidance on wood heater eligibility for tax credits

Thank you for this opportunity to provide comments.  IRS guidance on wood heaters is long overdue.  The Alliance is an independent non-profit organization that strives to represent the interests of consumers of wood and pellet heaters.  We believe a tax credit for wood and pellet heaters is essential as we transition from fossil fuel to renewable fuels. 

The IRS asked whether guidance needed to define the term "thermal efficiency rating"? If so, what testing procedures should the Treasury Department and the IRS consider requiring or permitting to be used by manufacturers to measure thermal efficiency and demonstrate ratings that are valid for purposes of the § 25C credit?

 

Summary: The most reliable method to protect consumers, ensure that tax credits are going to compliant models and create a level playing field for manufacturers is for Treasury/IRS to specify that eligibility is limited to units listed in the EPA Certified Wood Stove Database that have an overall weighted average efficiency of 75% or more using the higher heating value of the fuel.  

 

Using the EPA database to determine eligibility is the most effective solution from a variety of public policy perspectives but it is not without problems: multiple test methods result in disparate EPA seasonal average efficiency results for wood and pellet boilers, which are not comparable, and which are not helpful for consumers or for the purposes of setting an efficiency threshold for the tax credit.  The EPA is aware of the problem but an impending change in IRS guidance on wood heater tax credits is likely to hurt members of the industry who sell some of the most sophisticated modern wood heating equipment.  We urge the IRS to consult with the EPA on this problem and find a solution as soon as possible.

 

In addition, we urge the IRS to make it clear that the $2,000 tax credit for wood heaters is in addition to the $1,200 for other 25C qualifying home projects, not instead of them. The IRS should clarify that the full $3,200 is available to taxpayers. We also urge the IRS to confirm that 25C tax credits are available to renters, not just to owners of residences, based on the removal of the term “owner” by Congress.

Finally, the IRS asked for comments on certification or other requirements for home energy auditors.  We urge the IRS to affirm that when energy auditors are directed to inspect HVAC systems, that wood and pellet heaters are recognized as legitimate heating devices and need to be inspected for safety based on nationally recognized criteria, just as other heating systems are.  Various agencies and institutions such as DOE, NREL and BPI have begun to address this problem but wood heater remain marginalized, leaving many older, self-installed units that pose fire hazards and are not being properly inspected.

Background on wood and pellet heater testing: There is universal acceptance among test labs and manufacturers that efficiency is measured using in accordance with CSA B415.1-10.  When stoves are tested for EPA certification, the traditional test is to use the EPA’s “Method 28” which consists of 4 burn rates, from low (Category 1) to high (Category 4).  The lowest burn rate allows the lowest amount of air to flow through the stove and typically produces a higher efficiency.  High burn rates allow maximum airflow through the stove, and typically produce lower efficiencies.  The labs then combine these 4 efficiency numbers and produce “a weighted average efficiency” which is what is recorded on the EPA database of certified heaters as “overall efficiency.”

CSA B415 produces three types of efficiency: Overall efficiency, combustion efficiency and thermal efficiency.  The EPA uses Overall Efficiency to get an Average Overall Efficiency” and EPA guidance on testing deficiencies makes no reference to “thermal efficiency.”  Even within the wood and pellet heater industry, there is confusion between the terms “overall efficiency,” “thermal efficiency” and “weighted average efficiency.” The image below is an representative example of how test labs report efficiencies.  

Each of the four burn rates produces an overall efficiency number, and combustion efficiency number and heat transfer, or thermal efficiency number.  The EPA averages the four overall heating efficiency numbers to get a weighted average efficiency.  In the EPA database, this weighted average efficiency is in the column titled “Overall efficiency- HHV.” (The EPA used to use the term “Actual measured efficiency CSA B415.1 after they stopped using default, estimated efficiencies in 2015.)

There are eight labs approved by the EPA to conduct certification testing, including one in Canada, Czech Republic, Denmark and Sweden.  The labs do not use efficiency terminology consistently, and often just refer to “efficiency” rather than “overall efficiency” or “weighted average efficiency” rather than “weighted average overall efficiency.” All labs clearly distinguish HHV and LHV, and no lab uses “thermal efficiency” in their weighted averages, as far as we know.

However, some manufacturers will use “Heat transfer efficiency” otherwise known as “thermal efficiency” numbers to qualify models for the tax credit because they tend to be 1-2% higher than “overall efficiency.” Thus, if a stove has an average overall efficiency of 75%, it could have a single burn rate as low as 69%, using thermal efficiency numbers.  No manufacturer uses combustion efficiency for purposes of the tax credit as far as we know.  Combustion efficiencies tend to be in the 96-98% range.

Wood heaters are tested by EPA approved labs and then the EPA uses the data in the report to certify the stove for sale. Once it’s certified the EPA puts summary data on its Database of certified wood heaters. Since 2015, the EPA has also required manufacturers to post the non-confidential parts of their lab test report on their website.  Those reports are public and you can find the efficiency numbers for each burn rate, but they are not easy for consumers to navigate. On the contrary, they are dense, full of fine, highly technical jargon and are only used by regulators and experts.

Statistics: Currently, 25 of the 31 central wood heaters are eligible for the tax credit, using the EPA list.  113 of the 262 room heaters are above 75%, using the EPA list.  Overall, that would make about half of all heaters eligible, if the IRS were to use the efficiencies listed on the EPA database.

Public policy considerations: To achieve a level of transparency for the consumer, using the EPA database of certified heaters is an obvious solution.  Some consumers care about efficiency and the only place that consumers can make side-to-side comparisons is on the EPA database.  With pellet stoves, efficiency typically matters more than wood stoves because unlike cordwood, all pellets must be purchased, and a more efficient stove can save consumers by using less fuel.

If the IRS wants to be more lenient with manufacturers and allow more than about half of heaters to qualify, it could keep allowing manufacturers to issue certificates without any guidance, or specifically say that if any burn rate achieves 75% efficiency or more, it can be eligible for the tax credit.  If the IRS specified this, we expect all manufacturers would quickly adopt this system and about 80% or more of appliances would be deemed eligible.

Public policy is also served by setting a level playing field for all manufacturers, instead of allowing some brands to undercut others by claiming their units are eligible for the tax credit when they are below 75% on the EPA database.  Almost all US manufactures now use the EPA database to determine if their models are eligible.  

By setting an efficiency threshold for wood heaters, certain types of wood heater benefit.  The Alliance for Green Heat has monitored the changes to efficiency in wood heater for more than 10 years and documented the various ways that manufacturers claim that their stoves are eligible for the tax credit.  The averages below were calculated several years ago, when efficiencies were lower but the conclusion is remains the same: hybrid wood stoves have on average, the highest efficiencies are virtually all of them qualify for the tax credit, under any definition.  More manufacturers are building hybrid stoves in order to qualify for the tax credit and whereas there were only 6 models several years ago, today there are at least 21. Non-catalytic stoves, the cheapest, most popular, and most basic stove, have the hardest time reaching 75% efficiency. Today, only 15 out of 113 non-catalytic models are 75% or over.

From a public policy perspective, setting a 75% efficiency minimum, using the EPA database of certified heaters, is positive in that it tends to favor stoves that emit fewer particulate matters (PM) emissions.  Non-catalytic stoves tend to have higher emissions both in the lab and in the hands of homeowners if other factors are equalized such as moisture content of wood and ability of the operator. Pellet stoves and hybrid stoves tend to the cleanest, as used by homeowners.

Many taxpayers want to be able to download a certificate of eligibility to keep in their files, and taking a screen shot of the EPA list may not be as easy or feel as secure. The owner’s manual of the stove almost always has the weighted average efficiency, so that can also serve as proof of eligibility for the taxpayer.

There are two classes of heaters that would be unfairly penalized by an IRS requirement to base eligibility off the efficiency numbers in the EPA database.  The first is that multiple test methods result in disparate EPA seasonal average efficiency results for some indoor wood and pellet boilers which are abnormally low and are not comparable to other boilers or helpful for consumers or for the purposes of setting an efficiency threshold for the tax credit.  The EPA is aware of the problem, as is NESCAUM and NYSDERDA who are involved in testing programs to try to identify the calculations and assumptions leading to this problem and then find a solution.

The second are Masonry heaters are also penalized but since they do not yet have a pathway to EPA certification, the solution is more complicated. There are consistent and reliable ways to test factory-built masonry heaters and those manufacturers could issue Certificates of eligibility for the tax credit, but they will not be listed on the EPA database.  Standard combustion chambers used in site-built masonry heaters could also be tested but this is more complicated.  The Masonry Heater Association is the point group on this issue.

IRS options

The IRS has several options, depending on what their goals are.  

 

1.     The first, and best option, in our opinion is to use the “overall efficiency” numbers listed on the EPA database of certified wood heaters be the sole arbiter and end the practice of using manufacturer certificates, or only allow manufactures to issue certificates for heater models that are listed at 75% efficiency or higher on the EPA database. Many of the benefits of this are discussed above in the public policy discussion.

 

2.     There is a hybrid option of allowing manufacturers to issue certificates of eligibility if a model exceeds is 75% efficient or over for stoves and outdoor boilers or furnaces, or is 75% or more overall efficiency on any of their burn rates for indoor boilers or furnaces. 

 

3.     There is the current system, where manufacturers self-issue a certificate to declare that a particular model is eligible, sometimes without any reference to efficiency figures or definitions. This has resulted in manufacturers claiming models with weighted average efficiencies as low as 64% to be eligible. This has also allowed manufacturers to claim units that are not EPA certified to be eligible without providing any efficiency data. Another weakness of this option is that there is no agency with the time, resources, or agility to provide enforcement in this area, leaving consumers vulnerable to false claims. 

 

On the following pages, we have included representative samples of four types of manufacture certificates of eligibility for the tax credit.  The disparity of the language used and the range of models that are claimed to be eligible for the credit show a clear need for more guidance for the IRS.

 

A. Example of a certificate that claims eligibility without reference to efficiency, even though it appears all units are above 75% efficiency based on the EPA database.

 

B. Example of a company that claims its units are eligible, even though they are well below 75% on the EPA list and do not meet 75% even on individual burn rates.

 

C. Example of EPA non-certified stoves without EPA approved third party lab efficiency data to claim eligibility.

 

D. Example of a certificate that claims models are eligible solely because they are “qualified energy property” with no reference to efficiency.

 

Alaska building list of properly certified wood and pellet stoves

Lab certification test are designed to
burn as cleanly as possible and all
emission results must now be publicly
disclosed as of 2015.

Alaska Finds widespread deficiencies in EPA wood stove certification process 

Officials in Alaska are in the process of compiling lists of wood stoves and boilers that have met all the requirements of EPA certification and emit fewer particulates during the first hour of the test burn. Alaska regulations requires new wood heating appliances installed in the Fairbanks nonattainment area to meet additional regulatory requirements beyond obtaining a federal U.S. EPA certification. The regulations went into effect January 8, 2020 and Alaska has been working to implement those regulations since then.  The new regulatory requirements involve reviewing certification test reports for deficiencies and collected data regarding additional PM levels and then approve specific models of wood stoves and pellet stoves by updating their approved device list.

The Alaska Department of Environmental Conservation (ADEC) began this process as part of their efforts to address excess wood smoke pollution that contributed to Fairbanks becoming a non-attainment area.  The State’s Implementation Plan (SIP) to improve air quality began including measures years ago to crack down on dirtier wood burning appliances, such as outdoor wood boilers.

The current effort involves reviewing every stove’s certification paperwork to ensure that it includes all the elements that EPA regulations require, such as average CO, the manufacturer’s written instructions to the lab, firebox dimensions, efficiency calculations, burn rate calculations, raw data sheets, documentation of run anomalies, etc. etc. 

 

If you are not familiar with this brewing controversial initiative, you are not alone.  The first time most people outside a small group of manufacturers and regulators heard about this was a month ago, Sept. 18,  when a group of states weighed in on the litigation between HPBA and the EPA.  Their brief mentioned that the Alaska Department of Environmental Conservation was conducting a systematic review of wood-burning devices that have been certified to be compliant with EPA standards. The Department found that 59% of the certifications had inaccurate certification data, and that the EPA must have a way to check on manufacturers through audits. 

The start-up phase of a stove in the lab
should be consistent with how it is
described in the owner's manual.

The lists being developed by Alaska officials only pertain to what can and can’t be sold in the Fairbanks Nonattainment Area, a very small market.  But regulators, manufacturers and test labs we spoke to all say that this is having major repercussions.  For the EPA, it’s a wakeup call that they have not been sufficiently reviewing test lab reports before certifying stoves.  Test labs are under more scrutiny for various practices and are already  being asked by manufacturers to help ensure their tests come in under 6 grams during the first hour.  And scores of manufacturers are scurrying to provide additional information to Alaska and showing them the details that were in their test reports that Alaska officials missed.  

 

One of the main reasons that everyone is paying attention is that most of the people AGH spoke to agree that other states and change out programs could adopt the Alaska lists instead of using the full EPA list of certified heaters.  If more change-out programs, or even states adopt these stricter requirements, the efforts of a small city in Alaska will have greater national ramifications.  Some managers of change out programs that AGH spoke to say they interested to explore ways to identify cleaner cord wood stoves and are uncertain whether the EPA’s reduction from a de facto 4.5 to 2 grams an hour actually resulted in cleaner cord wood stoves. Incentive and change out programs often have adopted stricter efficiency and/or emission requirements and this may represent the next vehicle for those programs to guide how taxpayer dollars should best be used.

 

The last time state regulators made changes that went on to have national implications may have been in 1995 when Washington State adopted a 4.5 gram an hour state standard, when the EPA allowed up to 7.5 grams an hour.  The 4.5 gram an hour limit soon became a de facto national standard and 20 years later, HPBA insisted it was still the lowest that the EPA should go for the 2015 NSPS.  

Non-confidential portions of emission
test reports made the Alaska investigation
possible for the first time.

Aside from developing new lists of stoves that met all the requirements of the NSPS and emitted less than 6 grams for the first hour of all their certification test runs, Alaska is providing a wealth of information to the EPA, NESCAUM and others who are already in the process of developing a new federal reference test method for certifying wood stoves.  Some regulators the Alliance for Green Heat (AGH) spoke to now acknowledge that they see the current system as “broken” and that no one knew it was so broken.  On November 16, Alaska will be making its data public, showing which requirements in the stove certification process are most commonly ignored or overlooked and which ones are complied with.  

 

The data to be released on Nov. 16 includes a two-page data sheet on individual stoves, showing any deficiencies in their test lab reports.   Each manufacturer will have had up to 2 months to review their own sheets and provide corrections to ADEC prior to their public release.  The initial sheets prepared by ADEC have numerous mistakes according to several manufactures AGH spoke to and include many of the data points that ADEC initially said were not in their test report.  Test labs have been helping manufacturers find relevant data in their test reports, and ADEC will continue making corrections before and after Nov. 16.

 

It’s not yet clear if any test lab reports may be so deficient that the EPA could revoke their certification or require that the stove be tested again.  EPA officials are just beginning to grapple with how widespread the problems may be and what they can do moving forward to help fix problems that should have been in plain sight for so long. The EPA has identified and tried to correct some testing deficiencies in the past.  An AGH blog in July 2019 covered an EPA memo asking labs to correct lapses in reports on stoves tested with the ASTM E3053 test method.  This incident may have contributed to greater scrutiny by states including Alaska’s far more in-depth investigation.

An ADEC official taking
air quality readings on top
of a school.

The EPA certifies stoves based on the weighted average of the entire burn but requires labs to also report the amount of PM in the first hour.  Like efficiency, its data that must be collected and reported by the lab to the EPA, but there is no regulatory limit.  The Alaska initiative is making everyone ask whether the first hour of emissions may be an equally important indicator of a stoves cleanliness than the entire burn cycle.  

 

Currently, the way EPA approved test labs test stoves is by using the standard Method 28 or a variation of it. Lab technicians load stoves with an amount of wood based on the size of the firebox and let the fire go until all the wood is burned, which usually takes anywhere from 4 – 9 hours but can be longer.  During the last several hours of the burn, known as the “tail”, there is virtually no particulate matter being released, but those hours are still averaged into the overall calculation, with much be less than 2 grams an hour with cribs, or 2.5 grams an hour with cordwood. 

 

AGH reviewed scores of test reports and found that single PM reading from the first hour could be as high as 20 grams an hour and the average of all the first hour burns could be as high as 10 grams an hour, but it would be less than 2 grams when the cleaner parts of the burn and especially the tail end of the burn was included.  For Alaska, if any single run went over 6 grams, it was rejected.  Since start-up is the dirtiest part of the burn, identifying stoves that have cleaner start-up may help airsheds improve air quality.

 

Test labs that AGH spoke to noted that this will likely have the result of disqualifying a greater proportion of larger fireboxes.  The average firebox size is 2.2 cubic feet and an initial small sample of stoves with average first hour emissions over 6 grams was 3 grams an hour.  One test lab also said that this could disadvantage catalytic stoves that have no secondary combustion during start up prior to engaging the catalyst, which often occurs 20 – 30 minutes after lighting the fire.  Hybrid stoves, however, that use both air tubes and a catalyst are likely to have cleaner start-up, according to test labs.

 

Some manufacturers are angry that a state is using a brand-new emission metric – first hour emissions – that they could have designed for, if they knew it would be used in some markets to regulate stoves.  Now that it has been flagged, manufacturers certifying stoves going forward can try to meet that – or at least urge the lab to build  the type of start-up fire that will come in under 6 grams.  One of the primary goals of a lab is to familiarize themselves with the stove being tested so they can “optimize stove operations during certification testing.” Some regulators fear that this will just become another factor that manufacturers and labs will use to “game the system.”

 

The Alaska initiative will have a far greater impact on wood stoves than pellet stoves.  Extremely few pellet stoves emit more than 6 grams in their first hour and the testing regimen is more straightforward.  Ultimately, only a dozen or fewer pellet stoves may be disqualified by their review, out of the 98 models that are currently certified. Of the 144 currently certified wood stoves, up to a quarter to a third could be impacted.   New outdoor wood boilers are not allowed in Fairbanks already.  They will be reviewing pellet boilers for compliance.

An inversion in Fairbanks that traps
wood smoke close to the ground.,

Next steps

 

As of Nov. 16, Alaska will publish its review on virtually every EPA certified stoves.  On December 1, only those stoves that ADEC found had complete test reports will remain on the approved device list and be allowed to be sold in Fairbanks.  If a manufacturer needs more time to address potential report deficiencies, they can contact ADEC and if they commit to working to correct the deficiencies, their device may remain on the approved device list.  The first hour emission of 6 grams on each test run requirement, went into effect on September 1, 2020, and those devices have already been removed from the approved device list. 

 

Other jurisdictions, incentive and change-out programs will likely begin assessing whether the Alaska list represents better stoves for public funding.  Consumers who really care about a cleaner stove could also check that list before buying a stove.  For now, there are more questions than answers but the bottom line for everyone in the industry and the wider renewable heating community is that this is a story to watch.

Related stories

Veteran lab technician challenges Alaska's wood stove criteria (March 2021)

Alaska releases deficiency details on wood and pellet stove test reports (Nov. 2020)

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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