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Hearth & Home March 2014

Late & Disappointing

By James E. Houck

The EPA releases its proposed new NSPS. 354 pages, roughly 95,000 words.

As most of those in the hearth community know, the U.S. EPA Administrator signed the notice for the proposed rule for the Standards of Performance for: (1) New Residential Wood Heaters, (2) New Residential Hydronic Heaters and Forced-Air Furnaces, and (3) New Residential Masonry Heaters on Jan. 3, 2014. The rule is referred to as New Source Performance Standards or, frequently, simply by the abbreviation NSPS. The intent of a NSPS is to reduce air emissions that endanger public health or welfare.

The proposed rule is for “new,” New Source Performance Standards as there is also a current NSPS for wood heaters that was promulgated in 1988. Confusingly the rule(s) is/are alternatively referred to in both the singular and plural because, as noted, there are actually three new NSPS’s that have been grouped together. The Internet version of the proposed new rule in PDF format is a daunting 354 pages in length, which corresponds to roughly 95,000 words.

Among the members of the hearth community some of the adjectives that have been heard to describe the rule have been “complex,” “unclear,” “nebulous,” “undone,” “sophomoric,” “convoluted,” “repetitive,” and “perfunctory.” Some are unprintable.

In fairness to the EPA staff charged with preparing the rule, it’s a complex issue plus there are vocal special interest groups on “both sides of the aisle,” often with an agenda and less than a solid understanding of the facts. Nevertheless, bluntly put, the biggest problem with the proposed rule is that facts appear to have been ignored, responded to in an inappropriate manner, or simply not understood.

The old adage that knowledge is power comes into play here. If one looks objectively at the information that is available for wood heaters and EPA’s history of regulation, reasonable projections on how this all might play out can be made. Of course, one really needs to be a psychic to get it all right.

Business Limbo

The only thing that seems to move more slowly than the glacial speed of the EPA is, well – glaciers. The lack of agency responsiveness that would be totally unacceptable for most private sector enterprises can be seen in many of EPA’s environmental activities – perhaps this is just the nature of a governmental beast. The problem is it negatively affects private sector businesses that don’t depend on the constant flow of tax dollars for their survival, as does the EPA.

In the author’s over 35 years of working in the environmental arena, something heard over and over again by businesses is, “If they (a regulatory agency) would just promptly tell us what they would like us to do, we will do it.” The experience of many industries regulated by the EPA tells us not to expect prompt or succinct action.

The history of EPA’s dealing with wood heaters certainly follows this modus operandi. The first wood heater NSPS final rule was published Feb. 26, 1988. According to federal statute the EPA must review an NSPS every eight years unless such review is not appropriate in light of readily available information on the efficacy of such standards.

The reader can do the math – 1988 is a lot longer than eight years ago and the author knows of no information that would preclude such a review. Additionally, it took about four years to promulgate the final rule for the first NSPS with its implementation phased in over an additional four years.

We are currently at about the four-year mark for the new NSPS process and we have a long ways to go. Even if the final rule is published in a timely fashion, there is so much left for interpretation in the rule as it now stands that even after it is in place one could expect a fair amount of back-and-forth between heater manufacturers, testing laboratories, state and local regulators, and the EPA to iron out the problems, which will take time.

Of course, if litigation occurs things will slow down even further. The complexity of the new NSPS proposal combined with industry’s already strong negative reaction, suggests that lawsuits are certainly possible. One also has to remember that it’s not just industry that may initiate a lawsuit. The first NSPS process was started by a lawsuit filed by New York State and the Natural Resource Defense Council (NRDC) against the EPA.

Recently the states of New York, Connecticut, Maryland, Massachusetts, Oregon, Rhode Island, and Vermont along with the Puget Sound Clean Air Agency filed a lawsuit in U.S. District Court against the EPA in regard to updating the NSPS. Similarly, the American Lung Association, the Environmental Defense Fund, the Clean Air Council, and Environment and Human Health, Inc. have also filed suit against the EPA in U.S. District Court in regards to updating the NSPS. One does not have to be an astute student of litigation to know these types of lawsuits can drag out for a very long time.

Pre-Change-Out Fine Particulate Sources - Libby, MT

Pre-change-out, residential wood combustion was estimated to contribute about 66 percent to atmospheric fine particulate levels in Libby during the heating season (November 1 through February 28/29).

Future Draconian Actions

Section 111 of the federal Clean Air Act (CAA) authorizes the standards of performance for new stationary sources that cause air pollution that may reasonably be anticipated to endanger public health or welfare. This is the authority under which EPA is proposing the new wood heater NSPS. Many different air pollutant sources have a NSPS, for example municipal waste incinerators, petroleum refineries, pulp mills, cement plants, etc.

The problem with the NSPS for wood heaters is that its most controversial end use is not to protect public health or welfare directly, but it’s being used, or it’s planned to be used, as a tool by specific high-visibility state and local air quality jurisdictions for attainment or maintenance of national ambient air quality standards (NAAQS) for fine particulate material (a.k.a., PM2.5). The federal government puts a lot of pressure (including withholding of federal funds) on state and local jurisdictions to meet national ambient air quality standards.

Here’s where the rub lies. Best science, as discussed in the following sections, suggests that the proposed new NSPS for wood heaters, the way it is now written, is unlikely to make much of a difference in reaching or maintaining PM2.5 attainment for most airsheds. As a result, future, more Draconian regulations, such as a ban on all wood-fired heaters or even lower emissions standards than proposed in the new NSPS, may be proposed by specific state and local air quality agencies in their struggle to meet national ambient air quality standards for PM2.5. However, this is a double-edged sword, and perhaps a ban on all uncertified wood heaters may also encourage the sale and installation of new certified units or even wood stove change-out programs.

The Cumulative Number of Certified Freestanding Stoves

If history is a predictor of the future it will take a very long time for newly certified wood heaters with low emissions, as required by the proposed new NSPS, to make much of a difference in air quality. Since the last NSPS was promulgated, the fraction that certified freestanding wood stoves represent of the total number of freestanding wood stoves increased by only about 1.5 percent per year.

Hearth industry manufacturers’ shipment records tabulated since 1989 and supplied by the Hearth, Patio and Barbecue Association (HPBA) were compared to total wood stove ownership data.

Total wood stove ownership data were obtained from (1) American Housing Survey biennial reports, (2) HPBA biennial consumers surveys, (3) Mediamark Research, Household and Personal Appliances annual reports, and (4) Simmons Market Research Bureau annual surveys.

Minimal Improvement in Air Quality

The biggest problem with the proposed new NSPS is that it will only produce a minimal improvement in air quality that is degraded by wood smoke. There are four key reasons for this expected minimal improvement.

  1. The NSPS only regulates new heaters. Old ones will still be in homes.

  2. Air emissions in actual in-home use are much different than in the laboratory under specific and controlled conditions. The large emission differential between certified and uncertified emission levels is generally less under actual in-home use than under laboratory test conditions.

  3. The precision and accuracy of laboratory tests are not good enough to reliably document the very low emission standards suggested by the proposed new NSPS.

  4. Existing fireplaces, because they are so numerous, contribute 20 to 30 percent of the national inventory of residential wood smoke particles. This contribution will not change with the new NSPS since they are existing fireplaces, not new ones (remember the NSPS only regulates new sources), plus all fireplaces are specifically precluded from the proposed new NSPS because they are not heaters.

Finally, some believe that the proposed new NSPS might even worsen air quality because the predominate sociodemographic characteristics of wood heater households are rural, low-income and blue-collar. The increased cost expected for wood heaters designed to meet the more restrictive standards proposed by the new NSPS may make new wood heaters less affordable for these households and old wood heaters may stay in use longer. Whether this sociodemographic/cost factor will actually make the air quality improvements be negative is impossible to tell, but it will most certainly lessen the advantage of lower emission rates characteristic of certified units.

1. Old Wood Heaters

The new proposed NSPS clearly acknowledges that old heaters will not be impacted by the rule. The following phrase (with slightly different wording) is stated in four different places in the proposed rule document, “….this proposal does not include any requirements associated with wood heaters or other wood-burning appliances that are already in use.” Most wood heaters in use today are older uncertified heaters and, of course, some are heaters certified under the current NSPS. The emissions from these heaters (uncertified + Phase 1 certified under the current NSPS + Phase 2 certified under the current NSPS + exempt heaters + all the other categories of wood heaters) will not be changed.

A study was conducted for the HPBA on the change with time in the fraction of freestanding wood stoves that were certified since certified heaters first started to be sold in the 1988-90 time period. National surveys and industry records were used in the study. It revealed that after 24 years only about 40 percent of freestanding wood stoves are certified today. If this trend holds for the future, it suggests that it will take a very long time for heaters certified to the new standards to make much of a difference. Certainly, notable PM2.5 reductions will not be seen in the time frame that is commensurate with PM2.5 attainment goals.

Average PM2.5 by Heating Season - Libby, MT

The Libby, MT experience provides a clear illustration of the reduction in particulate emissions realized by the replacement of uncertified heaters with certified ones. When the fraction of PM2.5 attributable to wood smoke prior to the change-out of all uncertified wood-burning devices in the airshed to certified units is combined with the ambient concentration of PM2.5 measured during the heating season, the reduction realized can be estimated – it is 46 percent.

The average PM2.5 concentration during the November 1 through February 28/29 heatingseason dropped from 27.0 µg/m3 to a heating season average of 18.8 µg/m3 for the four heating seasons (2008-2009, 2009-2010, 2010-2011, 2011-2012) after the change-out program.

2. In-Home Emission Reductions

Not surprisingly, emission rates measured for wood heaters in actual in-home use are different than emission rates measured under laboratory test conditions. They are variable, do not correlate well in terms of ranking with certification levels, and are usually higher than the laboratory testing levels. The differential between high-tech certified wood heaters and old uncertified ones is typically reduced in home use.

It’s the general consensus among those with laboratory experience that wood heaters are forced by the system to be “tweaked” to do well under artificial laboratory conditions, but under in-home conditions with less than ideal fuel moistures, various draft conditions, unusual fuel geometries, inconsistent burning practices, and other differences their advantages are diminished as compared to more basic uncertified wood heaters.

Two very large databases, when analyzed without agenda, have shown that, on average, one can expect close to a 50 percent reduction in particulate emissions with in-home usage of currently certified wood stoves as compared to uncertified ones. Results from the two independent databases analyzed agreed quite well. One showed a 46 percent reduction and one showed a 48 percent reduction.

The two databases are (1) from work conducted in Libby, Montana, and (2) from numerous in-home field studies combined with in-laboratory studies simulating in-home use conditions. These two large databases consist of literally thousands of data points, involving dozens upon dozens of researchers and technicians, and sponsored by multiple agencies/organizations.

They do not support the statement in the proposed new NSPS document that “…. a wood heater complying with the NSPS would emit 75 to 86 percent less than conventional wood heaters.” Nor do they support the 90 percent reduction one often hears being bandied around the hearth industry. As the old saying goes, “It is what it is.”

When one considers that this approximate 50 percent reduction is for currently certified cordwood stoves with a calculated average certification value of 3.77 g/h as compared to uncertified cordwood stoves that are expected to have laboratory emission rates somewhere between 40 g/h and 70 g/h, it’s clear that heaters meeting the proposed new NSPS standard levels of 4.5g/h, 2.5 g/h and 1.3 g/h probably would not make much difference in actual in-home performance as compared to existing certified models.

Certified Wood Stoves Reduce Emissions by 48% in Homes

When the data from multiple in-home studies, plus multiple in-laboratory studies simulating in-home use, were analyzed, the percent reduction could be calculated. Efficiency was also taken into consideration when doing the calculation as higher efficiency effectively means lower emission because less wood is burned for the same heating demand. The percent reduction was 48 percent.

• A total of 618 tests were compiled to make the calculation. For the certified stoves, in total 409 emissions tests from 85 wood stoves comprised of 41 models were reviewed. For the uncertified stoves, 209 emissions tests on 62 stoves were reviewed.

3. The Limits of Laboratory Tests

Bluntly and succinctly put, laboratory testing using Method 28 as prescribed by the current NSPS is not good enough to define emission rates well at the lower end of the range for cordwood stoves; this is the range at which the proposed new NSPS suggests that standards be set. Anyone who has experience with industrial source sampling for particles knows that ± 20 percent is a rule of thumb. For wood heater testing, not only is there the uncertainty associated with the actual sampling process, but there is the added variability in the fire which almost reminds one of Chaos theory. (In fact, it might be a textbook example of Chaos theory.)

The combined uncertainty at the low end of the range when both the sampling process and the variability in burn conditions are considered is probably on the order of ± 50 percent. To get a really low certification value, a good roll of the dice is needed for a fundamentally good performing heater with inherently low emissions to start with. The good roll is really most needed in the low burn rate category as that is the category with generally the highest emissions.

There are, of course, many games that can be played with statistics, some real, some nonsense, and there will be a time and place for rigorous statistical analyses. Sadly, statistical analyses conducted by the regulatory community in support of the new NSPS have been largely in the nonsense category. To get an understanding of the uncertainty faced with laboratory testing one does not need statistics; just looking at EPA’s proficiency test data gives a clear picture of the problem.

As per §60.535(7) Standards of Performance for New Stationary Sources; New Residential Wood Heaters (Federal Register v. 53, n. 38, Feb., 26, 1988), accredited laboratories, “Agree to participate annually in a proficiency testing program conducted by the Administrator.” Between 1993 and 2000 a single stove model was used for this proficiency testing program, i.e., it was “round-robined” to all accredited test laboratories to compare emission testing results they got.

The results were obtained from the EPA for data submitted by eight accredited laboratories during that time period. As can be seen in the following scatter plot, the results show a large uncertainty in test results. Ironically, the only thing with high certainty about them is that they show that the testing procedures that are now part of the current NSPS are not good enough to document emissions at the low end of the range.

In-Home Emissions Compared to Lab Certification Results

The in-home emissions of certified cordwood stoves do not correlate well with certification test values due to the wide range of conditions under in-home use. The black dots are the mean of runs for a specific certified stove model, the bars are the standard deviation around the means for multiple runs with each model, and the green diamonds are the reported certification value for each stove model.

• In total, 409 in-home emissions tests from 85 wood stoves comprised of 41 models were reviewed. The names of the certified stove models were intentionally not identified but instead each model was provided a unique model code number.

Multiple Tests, Eight Labs, the Same Certified Stove

5H Particulate Emission Rates as Compared to U.S. EPA Certified Value. U.S. EPA NSPS Proficiency Testing Program 40 CFR §60.534, data show testing by eight laboratories with a single non-certified stove model (1993-2000) following NSPS methods 28 and 5G or 5H. (Data courtesy of U.S. EPA) A rigorous statistical treatment of the data shown in the graph can be found in the March 2011 issue of Hearth & Home.

4. Existing Fireplaces

As noted, the NSPS will not affect air emissions from existing fireplaces analogously to not affecting air emissions from existing wood heaters. The U.S. Census Bureau’s American Housing Survey (2011) estimated that there were 40,371,000 occupied housing units with useable fireplaces installed.  The HPBA’s Fireplace and Freestanding Stove Lifestyle, Usage and Attitude Study (2012) estimated that 50 percent of the fireplaces are wood fueled (the remaining being 36% gas and 14% electric), and that due to multiple fireplaces in some homes the average number per home is 1.2.  

Winners & Losers

At this early stage, with the complexity of 354 pages of text and with the proposed rule document requesting input and suggesting optional approaches, it is impossible to predict all possible ramifications of the proposed new NSPS rule; actually the three new proposed rules. Certainly there will be some winners and losers.

Heater Categories

Non-Catalytic Cordwood Stoves - With current technologies it may be tough for non-catalytic cordwood stoves to meet the more restrictive proposed future standards.

Catalytic Cordwood Stoves - A shift toward catalytic cordwood stoves away from non-catalytic cordwood stoves may occur because catalytic stoves will be more likely to be able to meet the more restrictive future standards.

Pellet Stoves - All pellet stoves will now be subject to the expense and delay of certification. Pellet stove technology can meet the new standards. Some models are already certified at low emission rates.

Single-Burn Rate Cordwood Stoves - Single-burn rate stoves will now be subject to the expense and delay of certification. Unlike adjustable-burn rate certified cordwood stoves, single-burn rate cordwood stoves do not have the typically high-emission, low-burn scenario. For this reason, they may be able to meet more restrictive future standards more easily. With certification status they may in the future be permitted to be installed in some jurisdictions that currently only allow EPA certified devices.

Masonry Heaters - Masonry heaters are inherently low emitting devices. With certification status they may in the future be permitted to be installed in some jurisdictions that currently only allow EPA-certified devices. The certification process for them is novel and will likely take time to develop and refine.

Furnaces - Furnaces will now be subject to the expense and delay of certification. In order of lowest emissions to highest emissions they are: Pellet << Catalytic Cordwood < Non-Catalytic Cordwood. Of course, pellet-fueled units would potentially be the most likely to easily be certified with their lower emissions. With certification status they may in the future be permitted to be installed in some jurisdictions that currently only allow EPA-certified devices.

Hydronic Heaters - Having gone through the painful process of EPA’s voluntary program, many solid low-emitting models have been developed. These models and technologies represent a step toward achieving the lower emissions thresholds listed in the proposed new NSPS. However, substantial improvement of their technology will still be needed to meet the more restrictive standards listed in the new proposed NSPS.

This corresponds to over 24 million useable wood-burning fireplaces in occupied housing units in the U.S. Even though these wood-burning fireplaces are on average used less frequently than wood heaters, still, what more needs to be said in terms of their wood smoke contribution?

One Size Doesn’t Fit All – The Same Wood Heater will Function Differently in Different Homes in Different Parts of the Country.
The chimney draft in an older three-story home at sea level in Maine during a cold Nor’easter will be much different than in a modern single-story tight home equipped with strong kitchen and bathroom fans at a mile high in Albuquerque during a mild winter day. Cold weather, a tall chimney, unimpeded air exchange with the outside, and low elevation tend to increase draft. Kitchen and bathroom fans counter draft.

The Players

Manufacturers - There is a price point at which wood heaters will not be attractive to consumers, yet low emission models will likely be more costly to design and construct. Potentially fewer units will be sold and/or at lower margins per unit; both suggest less profitability.

Attorneys - More clients, more litigation, more high-technology patents.

State, Local and Federal Regulators - More job security.

Distributors and Retailers - Undoubtedly, distributors and retailers will feel the manufacturer’s pain – less demand and lower margins.

Testing Laboratories - Difficult to call. While there will be more categories of heaters that will require testing, and most likely the testing will be more comprehensive, the new NSPS may precipitate a downturn in the industry suggesting fewer total new models will attempt to enter the marketplace and need testing. It is less likely that there will be new small laboratories because of the “admission price” of ISO accreditation. Business will be lost if R&D work will not be allowed to be conducted.

The Consumer - The big loser will be the consumer. His or her tax dollar is paying for the government’s role in the process. New heaters will cost more. The air he or she breathes will not be dramatically better.

A Fundamental Flaw

In the discussions leading up to the first NSPS during the late 1980s, it was widely recognized that polycylic organic matter (POM) was the group of chemicals that represented the most serious health threat from residential wood combustion. Measurement (and reduction) of POM compounds is consistent with the NSPS mandate of regulating “sources that cause air pollution which may reasonably be anticipated to endanger public health or welfare.” POM compounds are difficult and expensive to measure hence it was decided that particulate measurements would serve as a surrogate to POM measurements because, unlike POM, particles are easy and inexpensive to measure.

This is an imperfect pragmatic solution as POM compounds are partitioned between the particulate phase and vapor (gas) phase, i.e., some are in particles and some are vapors. While many of the same processes that destroy particles in wood smoke also destroy vapors it is not a tight one-to-one relationship, as anyone knows who has tried to compare carbon monoxide (a gas) emissions from wood heaters with particulate emissions. Even when in the same phase, different chemical compounds can be expected to be affected differently than other chemical compounds in terms of destruction and removal from wood-burning emissions.

Additionally, as more emission information has become available in recent years, it has become clear that a number of other vapor (gas) phase hazardous organic compounds in wood smoke are bad actors. Notably, when the emission factor of formaldehyde (a gas) from wood heaters is compared to toxicological thresholds, it is arguably more significant than particles and probably even POM in its impact to human health from wood smoke.

Bottom line: While certainly fine particles are injurious to human health, the NSPS has missed its true purpose in measuring them. Particulate measurement seem to have taken on a life of its own and most have forgotten why we are doing it.

Examples of the Range of Factors That Make Air Emissions from the In-Home Use of Wood Heaters Variable and Different Than Fixed Laboratory Tests

  • Wood moisture
  • Burn rates
  • The species of tree used for fuel (notably hardwood vs. softwood species)
  • Wood fuel piece size and shape
  • Cordwood versus dimensional lumber
  • Kindling practices and wood addition patterns
  • Chimney draft (chimney height, chimney condition, geometry of chimney, chimney connectors, chimney cap, home exhaust fans, e.g., kitchen, bathroom and clothes drier, air infiltration/tightness of home, and creosote accumulation)
  • The stove’s condition (new versus various levels of wear)
  • Wind gusts creating pressure pulses
  • Elevation as it effects available oxygen for combustion
  • Barometric pressure as it affects draft (home elevation and meteorological conditions)
  • Outdoor and indoor temperatures as they affect draft
  • Hot versus cold starts

A Fact to Ponder: In March of 2013, the emission rates of all 951 certified cordwood stoves listed by the EPA to that date were reviewed. The mean (average) was 3.77 g/h, the standard deviation around the mean was 1.70 g/h, and the median was 3.60 g/h. The fact that this analysis included higher-emitting models (Phase 1 units, very early Oregon-certified grandfathered units, and the earliest Phase 2 models) along with the more current and lower-emitting Phase 2 models suggests that even the 3.77 g/h mean and 3.60g/h median are a bit high. Additionally, certified pellet stoves are routinely certified at levels below 2g/h and even 1g/h. So why is the EPA considering new 4.5g/h, 2.5g/h or 1.3 g/h

Thoughts from the Testing Labs

What does the brain trust of hearth appliance testing think of the proposed new wood heater NSPS’s?

There are three notable senior professionals in the hearth-testing arena. Each manages an EPA-accredited wood heater laboratory and, together, they have an impressive combined experience of 74 years testing heaters. We asked all three the same two, straight-forward questions.

John Steinert ­– President,

Dirigo Laboratories, 10 years experience

Q. In terms of pragmatic laboratory testing, what are the key problems (or improvements) with the new proposed wood heater standards?

Having read the proposed rule from EPA on the NSPS, we have found a number of areas of concern that would affect the laboratories and their ability to test. Here are some of our concerns in no particular order.

  • Many of the recommendations submitted by Brookhaven laboratories would be onerous to the Laboratories resulting in dramatic cost increases for no benefit. Because we have not seen any of the supporting data produced by Brookhaven, we cannot effectively review any of their findings. We have serious concerns with the data produced and the seemingly overreliance on this data to implement policy.
  • The development of a cordwood test method should be pursued, but it is not necessary to perform both cordwood and crib testing on every single stove. Manufacturers should be able to choose between the two. It should be emphasized that emission limits from cordwood testing would not be on par with that of crib testing and new limits would have to be set.
  • Proposing that the heat output capacity of a category 4 (high burn) for hydronic heaters be within 10 percent of manufacturers rated heat output capacity throughout the category 4 and within five percent of the total series is not possible.
  • The cost of requiring ISO 17205 accreditation for current EPA laboratories would result in the loss of all the remaining small laboratories in the United States. These costs are prohibitive and would only result in the exact opposite of what EPA has been trying to encourage for many years now. The smaller laboratories specialize in emissions testing exclusively and losing them would be a tremendous loss to all concerned.

These are just a few of our concerns but we look forward to working with all stakeholders involved to achieve a final rule that we all can live with.

Q. After working with many hearth appliances, how do you think the proposed NSPS will affect the quality/performance/complexion of future wood heaters?

The current and proposed standards give a false sense of how cleanly currently-regulated wood heaters actually perform under laboratory conditions versus in the field. The tightening of emissions standards should always be pursued as technologies improve, but there is a disconnect between laboratory results and performance in the field.

Laboratory results will always be limited in their ability to mimic field performance even if cordwood testing is adopted. The end user will always be the wild card when it comes to performance in the field. These issues have always and will continue to be a problem where there is no easy answer. 

The ability of the NSPS to affect the performance of wood heaters will be limited and will vary between appliances. The addition of previously unregulated appliances such as hydronic heaters and wood-fired furnaces will undoubtedly result in cleaner emissions under real world circumstances. In this area, the NSPS will have the greatest effect. Appliances that have been subject to regulation since the first NSPS will probably not have as large an impact as most would hope.

Rick Curkeet, PE

Intertek Testing Services – Chief Engineer
Building and Hearth Products, 35 years experience

Q. In terms of pragmatic laboratory testing, what are the key problems (or improvements) with the new proposed wood heater standards?

Curkeet: The new NSPS proposal is a huge disappointment. The document borders on being incomprehensible and is full of unsupported claims, contradictions and many just plain bad ideas. It’s over 350 pages long, but I think it would take twice that many pages just to explain all the things that are wrong with it. But, trying to focus on just the test method and laboratory issues, I will try to provide some examples. So far we have identified over 20 specific areas where the proposal is off track. Some of the most obvious are as follows:

  • Failure to simply specify the new ASTM Test Methods as published. EPA proposes to modify ASTM E2780 for wood-burning stoves in several ways. These include much tighter restrictions on the test fuel-load including moisture content of 22.5 ± 1 percent, load weight of 7.0 lbs ± 1 percent, and coal bed weight of 22 ± 1 percent of the test load weight. These much tighter limits would make conducting a compliant test much more difficult and much more expensive.

    Presumably EPA thinks these specifications would reduce the very large variability that is inherent in wood-burning emissions. However, there is no evidence that this is true and the specifications would make the laboratory test even less representative of real world operation than is already the case with a lumber crib fuel-load.

  • EPA has proposed their own test procedures for hydronic heating equipment rather than simply specifying ASTM E2618-13. The EPA procedures have not been vetted through a consensus process. There are many technical deficiencies in the EPA procedures that I will not try to detail here.

    One glaring issue, though, is that regular hydronic heaters would be tested using an oak 4 x 4 lumber crib fuel while the same appliance, if connected to a partial heat storage system, would be tested with cordwood. Since it’s quite likely that manufacturers can design units that would comply with the Step 1 stand-alone hydronic heater requirements and also benefit from connection to heat storage, this provision could create a design and R&D nightmare for manufacturers. They would have to test with lumber cribs for one application and cordwood for another. There is no certainty that this could be done without design modifications.

  • EPA seems to say that they want to stop applying the so-called Method 5G to Method 5H conversion equation which all experts agree was not correct from the beginning. However, the actual proposal does just the opposite and would require the application of the conversion formula.
  • EPA included an indication of their intent to specify ASTM E2779-10 for testing of pellet appliances; however, the proposed rule contains no reference to the ASTM pellet fuel appliance test method. If they do reference it in the final rule, would they also require that the 5G to 5H adjustment equation from method 28 be used? It seems to us that it would be blatantly unfair to apply this so-called correction (which always increases the final emissions rate) to one product type and not others.
  • EPA proposes that some appliances be required to be tested with both lumber cribs and cordwood. The manufacturer could apparently choose which to base their certification on, but both would be reported to EPA. Presumably, these results would be available to the public and state regulators.

    This would obviously at least double the cost of testing. It would impose a huge burden on the test labs as they would need space and conditioning facilities to manage two stocks of test fuel. It would also almost certainly result in some state or local regulators imposing requirements for compliance with the “other” fuel, e.g. “we don’t care if the appliance passed with cordwood, in our state we require it to pass with cribs,” or vice versa.

  • EPA has chosen to simply ignore the issue of emissions test variability, which is known to be comparable to the proposed compliance limits. That is, an appliance that might have a true average emissions rate (the average value that would result from a significant number of replicate test series) of ±4 g/hr could produce a result anywhere from less than 1 g/hr to over 8 g/hr in any single test series.

    EPA assumed that the emissions test would be repeatable within about ±1 g/hr back in 1986. We now have a substantial database from the EPA-required proficiency test program that shows this assumption was wildly optimistic and that the actual variability is in the range of 3 to 5 g/hr. This fact means that even with a very good low emissions design, passing the test at the limits proposed will be substantially a matter of chance, not sound science.

    EPA has even proposed a modification to the Proficiency Test Program that would require that labs produce results within 10 percent of the test unit’s certified value or have to run an additional two-test series. EPA apparently thinks it has the power to reduce variability by fiat – a ridiculous notion. Perhaps EPA thinks that laboratories should be able to produce a targeted result – within 10 percent of the certified value – by careful manipulation of the test process.

If this is the case, then the concept of objective independent testing to determine compliance is turned on its head. The result of a test series is whatever it is. We cannot ethically, morally or objectively run tests in a manner that attempts to produce a predetermined result.

Intertek Testing Lab.

Q. After working with many hearth appliances, how do you think the proposed NSPS will affect the quality/performance/complexion of future wood heaters?

If the proposal stands, I’m afraid I don’t see any long-term future for the wood heating appliance industry. The Step 2 limits proposed are probably unattainable with hand-fired cordwood appliances – at least at a price that the vast majority of people could afford. There is no reliable data that indicates these extremely low levels can be met. I believe, whether EPA knows it or not, that they are in the process of setting the date for the demise of the wood-burning appliance industry. That date will be early 2020.

I would note here that the so-called EPA-Certified Stove Database contains data that is subject to the same large variability discussed earlier. This means that in any sample, some results will be near the high end and some will be near the low end of the distribution. Of course, EPA would only see the low results in their certification program.

When only a single result is considered there is always a chance that it simply represents a result from the low end of the range of possible results. Thus, the very few certified wood stoves with very low emissions ratings might well just represent those few lucky cases where chance favored the manufacturer. We cannot know unless we test the same product several times and see what the actual range of results looks like. But to my knowledge no one has done this.

But we do have the results of 25 years of EPA proficiency testing to inform us, and the news is not good. Random variability is larger than the proposed emission limits. It will not be possible to determine compliance with any reasonable certainty under these conditions.

Unfortunately, I don’t think the EPA approach will help the environment at all. Most people who seriously heat with wood are rural, relatively low-income folks who heat with wood because it’s cheap and readily available to them and allows a substantial cost savings versus electricity, oil or propane. Not many people heat with wood these days if they have natural gas available.

I cannot imagine that many people who currently rely on an older wood stove, furnace or boiler would spring for a new EPA low-emissions appliance that may cost several thousand dollars. Getting people to change out old wood stoves for EPA-certified stoves took substantial subsidies from government and industry. So I think the new rules, if adopted, will essentially make an old, dirty wood stove a more valuable commodity.

Last fall I personally bought a new wood stove and took my 25-year-old stove to the local recycling center. I did not even get it out of my truck before three different people approached me to ask if they could have it. I was tempted to start an impromptu auction. If I were young enough and looking to start my own business, I think refurbishing and selling used wood stoves would be a lucrative choice.

My guess would be that the only products that survive long-term might be pellet stoves, outdoor hydronic heaters and perhaps a few very expensive wood stoves. Pellet stoves should be easiest to design to meet lower limits. But we have seen very few that would meet the proposed Step 2 limit (1.3 g/hr) and we have no information on variability for pellet stove emissions tests.

Outdoor hydronic units typically have a market in rural applications with very high heat loads where the savings achievable vs. oil or propane can produce a reasonable payback even on a $15,000– $20,000 investment. Even at that, the proposed Step 2 limit of 0.06 lbs/MM Btu is unlikely to be achievable.

The data cited by EPA to justify this is either from tests known to be flawed or European tests that are very dissimilar to the U.S. tests and measure only a fraction of the particulates that we measure. High-end wood stoves will probably still sell to the wealthy as mainly decorative design elements. Of course, wealthy folks would probably not use them much so the low-emissions technology wouldn’t be much of a factor.

The original NSPS along with lower natural gas prices and demand effectively reduced the number of wood-burning appliance manufactures by about 75 percent over just a few years. The new proposal could easily knock out a similar chunk of the remaining industry.

It seems clear that the EPA and state air quality regulators have no idea just how clean a wood stove at 4.5 g/hr or a hydronic heater at 0.32 lbs/Million Btu really is. When operating at these levels there is virtually no visible smoke or even noticeable odor. If we accept EPA’s contention that the 4.5 g/hr and 0.32 lb/MMBtu limits represent a 90 percent reduction in emissions from unregulated products (I think it’s even greater), then EPA’s Step 2 proposals would represent a 97 percent and 98 percent reduction. It is very hard to imagine that such a small additional reduction – even if it is attainable and could be reproduced in the field – could possible justify the tremendous costs and loss of businesses and jobs that are sure to result.

My greatest disappointment is that EPA and state regulators seem to be intent on killing off the one form of renewable, carbon neutral, heating energy that has succeeded with little or no government subsidies or support and is economically viable on its own, while pouring billions of taxpayer dollars into wind, solar and ethanol – much of it now down the proverbial rat hole. Millions of homeowners have been able to substantially reduce their fossil fuel consumption while saving money by using safe and clean modern wood-burning appliances. It would be a real disservice to consumers, manufacturers, retailers and the environment to destroy this industry.

We and many others will be filing extensive comments in an effort to bring EPA around to a reasonable and workable regulation. If we fail, it won’t be pretty.

Ben Myren – President,

Myren Consulting, 29 years experience

Before answering the two questions, I think we need to first ask ourselves what the primary goal of these proposed new rules is. Is it to have a test method that has wonderful reproducibility in terms of lab test results? Or is it to have a test method that results in stoves that perform well in the field? 

The two issues are not necessarily related. Having spent a lot of time during the past several years trying to educate folks about the reality of what happens in a test lab when an appliance is being tested, I had great hopes that we (industry, government and others) would be able to sit down and negotiate a new rule based upon science and fact. Sad to say, my efforts and the efforts of others who felt the same way were to no avail.

Q. In terms of pragmatic laboratory testing, what are the key problems (or improvements) with the new proposed wood heater standards?

The only real key improvement in the NSPS is the proposed change from a crib fuel- to a cordwood fuel-based test method. Many (most? all?) of these proposed changes/test requirements are based upon a “wish list” from an alternative universe where additional requirements are cost-free and need not be based upon the reality or the science of testing and manufacturing appliances that burn wood. 

Industry and the labs also have their own alternative universes where, more often than not, poor quality work is left unchallenged and there are no substantial repercussions for it. All of us need to refocus on what I feel has to be the primary goal of these regulations - the products have to work in the field – and work to develop a test method that results in products that do just that!   

One example should suffice to illustrate my point about cost. The proposed rules limit the particulate matter (PM) sampling test method to EPA M5G-3/ASTM E2515, which requires the use of dual sampling trains with 47mm filter sets that have two filters per set. Filter set changes are to be required every hour.

With the increased fuel loading density for cordwood, a medium low burn for a small cat stove (UFV = 2.9 ft3) can last 13-plus hours. That translates into at least 28 filter sets and probes that have to be desiccated (dried), tared, assembled and leak checked prior to the start of the test, 28 filter sets that have to be sequenced on and off at the appropriate times during a test, and then 28 filter sets that have to be leak checked, disassembled, the probes and filters weighed to a constant weight and then cleaned after a test. 

Plus you need to have the equipment and space to be able to do this on a production basis, and someone to keep track of and process all of the paperwork. Compare that to what we do now with EPA M5G-1 where we use one filter set with two filters for an entire test, clean it, reload it and use it the next day.           

Q. After working with many hearth appliances, how do you think the proposed NSPS will affect the quality/performance/complexion of future wood heaters?

There is an ASTM cordwood test method in the works, but it still needs a lot of work and is at least a couple of years from final publication. What EPA might do with it after it’s published is anybody’s guess. Having said that, I think the change to a cordwood-based test method should improve the field performance of wood stoves because stoves will now be tested with real world fuel. Whether it will be possible to meet the proposed final emission standard of 1.3 g/hr without adding a lot of complexity, e.g., automatic controls, hybrid technologies, etc., remains to be seen. 

But no matter what the design configuration(s) used for compliance are, quality considerations will be of utmost importance simply to ensure the stoves work as intended. It’s one thing to produce an R&D prototype that will pass a lab test. It’s another thing to produce that same stove on a day-to-day assembly line basis. Quality will be job 1. However, one thing is certain – the cost of new appliances will have to go up.

About the Author

Dr. James Houck is an independent consultant specializing in product development, litigation support, environmental impact analysis, energy conservation, and strategic marketing. He is an adjunct faculty member at the University of Portland responsible for teaching air pollution. He is a research associate with Dirigo Laboratories and a staff writer for Hearth & Home. He can be reached via email.

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