8431 Murphy Drive 

Middleton, WI 53562 

Telephone: 608 836 4400 

Facsimile: 608 831 9279 

www.intertek-etlsemko.com 

3 November 2009 

WESTAR NSPS Meeting Regulatory Attendees 

RE: Comments Regarding the EPA NSPS for Woodstove Emissions

Dear Conference Attendees: 

The following recommendations were submitted to the HPBA Industry group earlier 

this year. 

NSPS Revision Recommendations 

Having been involved in the original NSPS negotiation and providing testing services 

since its inception, we believe we have substantial technical and practical experience 

to draw upon in offering recommendations that will improve the process. There is 

broad agreement that there are many areas of the current regulation that can be, 

and need to be, improved. In some cases the proposals are straight forward and noncontroversial. However, some of the suggested revisions will require considerable 

discussion, debate and perhaps compromise to achieve consensus. We believe that 

the re-opening of the NSPS provides an opportunity to address all of the important 

issues and concerns that have developed in over 20 years since the original NSPS was 

issued. 

As a Third-Party testing and certification agency Intertek’s interests in this process are 

primarily technical. The recommendations that follow are intended to improve the 

process of evaluation and certification of affected products in terms of accuracy, 

credibility, fairness and relevance. 

In the last few years there has been a great deal of activity in the voluntary standards 

development arena dealing with many of the relevant issues. We believe that this is 

the most appropriate and efficient forum to take on the task of updating, expanding 

and refining the technical documents involved with testing and rating bio-mass 

fueled appliances for emissions and heating performance. 

Intertek Testing Services NA, Inc. 8431 Murphy Drive, Middleton, WI 53652 
8431 Murphy Drive 

Middleton, WI 53562 

Telephone: 608 836 4400 

Facsimile: 608 831 9279 

www.intertek-etlsemko.com 

Both ASTM subcommittee E06.54 and the CSA B415 committee have active standards 

development programs that have proven to be capable of developing test methods 

that achieve a broad consensus among interested stakeholders. 

The following are general comments on those specific areas where changes will, in 

our view, greatly improve the process of assessing and certifying the performance of 

effected appliances while maintaining or improving the impact of these appliances on 

air quality. 

1. EPA Methods 5H and 5G should be withdrawn and replaced with a 

reference to ASTM E2515. 

Reason: The application of 4 different emissions collection and measurement 

methods and the inclusion of the so-called 5G to 5H adjustment factor 

produced many opportunities for variability in results and poorer 

reproducibility. This issue was thoroughly discussed and debated in the ASTM 

E06.54 subcommittee and the consensus achieved agreed that a single 

universal method was appropriate and should be applicable to all types of 

solid fuel appliances. The current EPA Methods contains restrictive 

requirements which do not allow direct application to bio-mass appliances 

other than woodstoves and pellet-burners. ASTM E2515 is a much more 

flexible method that applies to particulate emissions measurement from any 

bio-mass fueled appliance. 

2. If ASTM E2515 is adopted, any discussion of particulate emissions limits 

based on data from the current NSPS should take into account the effect 

of the “5G to 5H adjustment factor”. For example it should be recognized 

that the 4.5 grams per hour “Washington State” limit equates to 3.0 grams 

per hour as measured by EPA method 5G or ASTM E2515. 

Reason: The so-called adjustment factor has the effect of inflating the 

reported emissions by larger and larger amounts as the actual emissions rates 

decrease. This is counter to what should be expected. It should be obvious 

that as the actual particulate emissions approach zero so should the results of 

any measurement method. 

In essence the application of an adjustment factor results in converting a direct 

and accurate measurement with a small measurement uncertainty into a 

significantly different result with no sound technical justification. 

Intertek Testing Services NA, Inc. 8431 Murphy Drive, Middleton, WI 53652 
 11/3/2009 Page 3 of 8

3. Voluntary consensus standards should be adopted wherever possible. This 

would include CSA B415.1 which is currently undergoing a substantial 

revision process and will address many more types of solid fuel appliances 

than are currently covered by the EPA NSPS. In addition ASTM E2618 for 

Hydronic Heating Appliances and E2558 for fireplaces are already 

published and should be referenced to support emissions certification. 

Reason: It is clear that all types of bio-mass fueled appliances will increasingly 

be targeted for regulation to achieve ambient air quality requirements. The 

use of existing consensus standards provides the quickest and most credible 

approach to providing a fair and reliable basis for determining product 

compliance. In addition, consensus standards are required to undergo regular 

review and revision cycles which result in continuous improvement and 

refinement of the methods. The fact that the EPA NSPS has not been reviewed 

or revised for over 20 years in spite of many significant issues and short 

comings should be reason enough to adopt voluntary consensus standards. 

The US federal government has a clear policy directive (OMB Circular A119) 

stating that government regulatory agencies must use voluntary consensus 

standards when such standards are available and meet the regulatory need. 

We believe that the ASTM and CSA standards developed in this area meet the 

criteria for use in regulatory programs. 

 

4. Replace direct EPA product certification with independent third-party 

certification per ISO/IEC Guide 65. 

Reason: The existing NSPS process for certification has lacked an effective 

follow-up and auditing system. The Random Compliance Audit provisions 

included in the NSPS have never been exercised. The Selective Enforcement 

Audit process has only been used in extreme circumstances. 

We contend that third-party certification provides a substantially more robust 

and reliable approach to assuring on-going compliance of production units 

than the procedures and requirements contained in the current NSPS. 

Third-party certification is already in place for the affected products under the 

requirements of appliance safety standards and building codes. This process 

provides a high level of assurance that certified production units conform to 

the certified design represented by the sample tested. This process includes 

regular unannounced inspections of the production facilities to verify that 

certified units continue to be manufactured to the documented design 

Intertek Testing Services NA, Inc. 8431 Murphy Drive, Middleton, WI 53562
 11/3/2009 Page 4 of 8

specifications. The addition of an emissions and efficiency certification under 

this process would only require the additional testing necessary to determine 

compliance. Thus, this approach adds very little cost to the product while 

substantially increasing the reliability and credibility of the performance 

certification. 

5. Reformulate all emission requirements for heating appliances in units of 

emissions mass per unit of heat output. In addition, include a requirement 

for product certifications to include measured heat output and efficiency. 

Reason: Solid fuel heating appliances can and should be evaluated for heating 

efficiency. The failure of the EPA NSPS to include a measured efficiency has 

provided no incentive for appliance designers to work on improving heating 

efficiency. It should be recognized that greater efficiency translates directly to 

less fuel consumed to satisfy a given heat demand. This results in both lower 

emissions and lower consumption of fuel resources. 

Stating emissions limits in terms of mass per unit of heat output (e.g. g/MJ or 

lbs/million Btu) provides for an equitable basis for regulation of all types of 

heating appliances from small room heaters to large furnaces or boilers. 

Including efficiency and heat output information on product labels will 

provide consumers with relevant and easily understood information upon 

which to base a more informed purchasing decision. 

6. Specify CSA B415.1’s efficiency test procedure to determine direct heating 

appliance efficiency and heat output. Use ASTM E2618 to determine 

delivered heat output and efficiency for Outdoor Hydronic Heaters. 

Reason: CSA B415.1 has a stack loss test method that produces reliable and 

accurate test results. Revisions are in progress that with improve and simplify 

its application and broaden its applicability to more appliance types. The new 

version of B415.1 will also include procedures for determining the delivered 

heating efficiency of forced air furnaces. ASTM E2618 provides an appropriate 

and accurate method to measure the output and heating efficiency of ODHH 

appliances. 

Reliable and accurate efficiency methods are necessary to support the US BioMass heating appliance tax incentive program. 

Intertek Testing Services NA, Inc. 8431 Murphy Drive, Middleton, WI 53562
 11/3/2009 Page 5 of 8

7. Eliminate the requirement for woodstoves and pellet burners to operate at 

under 1 kg/hr burn rate and replace the EPA NSPS categories with burn 

rates specified in terms of percentage of maximum burn rate. 

Reason: The requirement for wood stoves to operate at under 1 kg/hr burn 

rate should be dropped in favor of the minimum being a percentage of the 

maximum. This requirement has been unnecessarily design restrictive. Not all 

wood stoves are used to heat a single room of a typical single family home. 

This requirement has eliminated larger woodstoves which might have 

reasonable applications in heating larger open spaces such as workshops, 

larger homes with open floor plans, ski chalets, etc. Only 2% of the 733 

woodstoves certified by EPA had maximum rated outputs over 60,000 Btu/hr. 

Experience has shown that it is very difficult to design a woodstove that has a 

turn down ratio of more than about 4 to 1 that will operate cleanly and 

satisfactorily throughout its operating range. Of all the EPA certified stoves 

only 9% have a turn down ratio of 5 to 1 or more (many are pellet burners). 

The average is 3.2 to 1 (i.e. minimum burn rate is 31% of the maximum). 

The result has been virtually no availability of new clean burning woodstoves 

to replace larger old technology stoves being used where larger heat demands 

are a real concern. 

The CSA B415.1 burn rates of: <35%, 35 - <53%, 53 - <76% and 100% should 

be considered. 

8. Eliminate “Gram per Hour Caps”. 

Reason: A gram per hour emissions cap serves to limit the output rate of 

affected appliances which actually burn very cleanly. This is a particular issue 

for furnaces and hydronic systems which are generally used to provide whole 

building heating requiring larger heat output capacities. For example, a cap of 

18 grams/hour limits the output of an appliance that would meet a 0.2 g/MJ 

(0.46 lb/MMBTU) limit operating at 80% efficiency to a burn rate of 5.7 

kg/hour and a maximum output of 86,000 BTU/hr. Further, it should be 

understood that properly sized heating appliances operate at or near their 

maximum output 2% or less of the heating season. Thus, even though the 

hourly emissions rates may seem high, the environmental impact is actually 

very small. Most all affected appliances will operate in the lower 1⁄2 of their 

range for over 80% of the heating season where the typical gram per hour 

caps would not be exceeded by any compliant appliance. 

Intertek Testing Services NA, Inc. 8431 Murphy Drive, Middleton, WI 53562
 11/3/2009 Page 6 of 8

Caps also affect heat storage systems which are designed to burn large wood 

loads very fast and store the heat for use over long periods. These appliances 

can burn extremely cleanly with very low emissions per unit of delivered heat, 

but may exceed the “cap” during the infrequent burn cycles. 

Where heating applications require larger heat demands, caps could result in 

users being forced to buy fossil fueled appliances rather than using renewable 

bio-mass fueled equipment. Alternatively users might buy multiple smaller 

units to meet a larger heating demand application to work around the cap 

issue. 

9. Test all heating appliances with the fuel that they are intended to burn. 

Reason: While we understand the trepidation many might feel regarding the 

cribs versus cordwood issue, this may well be the most important single issue 

facing the industry in the NSPS revision process. We now have perhaps the 

only opportunity there will be for the foreseeable future to debate and resolve 

this question. 

The primary argument to retain the EPA Method 28 Douglas fir crib fueling 

protocol centers on two issues. 

a. Cribs are necessary to achieve reproducible and repeatable test results. 

b. The existing database upon which we must rely to determine “best 

demonstrated technology” was generated using cribs. Thus, any new 

regulation limits will require future testing be done with cribs. 

The first argument is demonstrably wrong. An increasingly robust data base of 

tests using real world cordwood fuel in multiple replicate tests of multiple 

appliances has shown variability that is no greater than that achieved with 

cribs. In fact, the available data from the EPA NSPS accredited laboratory 

round robin tests with cribs showed very poor repeatability and 

reproducibility. 

While the second argument may appear convincing, the fundamental 

assumption inherent in the NSPS was that appliances tested using cribs would 

perform similarly when operated in the real world with cordwood. In fact, 

many designers have gone the extra mile and tested their appliances with 

cordwood just to make sure that they would not perform poorly. However, no 

one has been required to do this and there are quite a few EPA certified units 

Intertek Testing Services NA, Inc. 8431 Murphy Drive, Middleton, WI 53562
 11/3/2009 Page 7 of 8

that do not do nearly as well in the real world as their certification would 

indicate. In any case, the limits that apply are used in ambient air quality 

modeling and assessments and there is no reason to believe that the levels that 

have been achieved when burning cribs could not be achievable when burning 

cordwood. If this is not the case, then one must question whether the entire 

concept of the EPA NSPS is based on a false assumption. That is, a clean 

burning appliance in the lab should be a clean burning appliance in the field. 

There is no question that whatever test procedure is mandated, manufacturers will 

soon produce products that will comply. It will not matter to many of them whether 

or not these new designs perform in the field as well as they do in the lab, and that is 

the real issue. All the evidence available indicates that substantial differences in both 

emissions and heating efficiency are likely depending on whether cribs of cordwood 

fuel is used. There is nothing that indicates real world use will be likely to result in 

better performance than in the lab. In fact, field performance may be little improved 

if products are tested with a very different fuel than they will be used with. 

It is often necessary to sacrifice some element of realism in designing repeatable and 

reliable laboratory tests. It is, however, not desirable to do so. And it is most 

certainly counter productive to do so when it is not necessary. 

I have heard additional arguments in favor of the crib fuel load from its proponents 

that boil down to these: 

a. Cordwood loading cannot be well enough defined to prevent 

manipulations that could result in obtaining better performance than 

the appliance is really capable of. 

b. Cordwood loading is too random to provide consistent or reproducible 

results. 

c. Crib fueling only produces variable results because the control of density 

and moisture content is not tight enough. 

No one has explained exactly how one manipulates a fuel load that is too random to 

be reproduced to get unrealistically good results. In fact, the only manipulation I can 

imagine one might do to achieve this would be to select cordwood pieces of very 

uniform size and length and carefully stack them with very specific spaces between 

pieces – i.e. make them into a crib. In effect, a requirement to use cribs simply forces 

everyone to use the same fuel manipulation scheme rather than requiring designs to 

be robust enough to burn cleanly and efficiently with fuel loads that represent real 

world variability. 

Intertek Testing Services NA, Inc. 8431 Murphy Drive, Middleton, WI 53562
 11/3/2009 Page 8 of 8

Intertek Testing Services NA, Inc. 8431 Murphy Drive, Middleton, WI 53562

Even tighter control of density and moisture content might serve to improve 

repeatability, but at the cost of even greater deviation from real world operation. 

There are two clear trends that have emerged from the hard data that has been 

produced in this area. One is that cribs provide no improvement in repeatability over 

cordwood. The second is that cribs are not predictive of cordwood emissions or 

efficiency performance. Given these facts, retaining a crib based test method will 

likely suffer from ongoing credibility problems as it is obvious to everyone that 

consumers will not operate these appliances with carefully constructed lumber cribs. 

I offer the following question regarding the fueling issue: 

Which appliance design represents a superior technology: one that burns consistently 

cleanly only when operated with an exactingly designed and controlled fuel load, or 

one that burns consistently cleanly with random and inconsistent fuel loads? 

We believe the answer is obvious and would further point out that we have seen 

many examples of appliances that consistently burn very cleanly using cordwood fuel. 

It is reasonable to assume that of the currently available certified woodstoves a 

substantial proportion would pass the emissions requirement if tested with 

cordwood. It is also likely that a significant proportion would not. Under the current 

system there is no way for regulators or consumers to determine which ones are 

which and this is the heart of the issue. 

10.Consider Revision of the “5-Minute Start-Up” requirement for manually 

controlled appliances. 

Reason: It is well known that start-up with a fresh fuel load can be critical in 

obtaining good combustion performance. The 5-minute limit seems arbitrary and 

over-rides reasonable manufacturer’s operating instructions. 

Many of the so-called “outliers” in EPA woodstove test programs are simply the result 

of failure to operate at a high burn setting for long enough to establish and sustain 

secondary combustion. 

Real world performance would benefit from more specific instructions to the user on 

how to assure good start-ups when reloading. Laboratory testing should include 

following such instructions provided they are clear and reasonable 

INTERTEK 

Rick Curkeet, PE 

Chief Engineer – Hearth Products