 |
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 Are in-home emission reductions as compared
to conventional stoves shown in Table 1 for catalytic and non-catalytic
certified stoves reasonable?
- 1.2 Are efficiencies shown in Table 2 for
catalytic and non-catalytic certified stoves reasonable?
- 1.3 Can catalytic technology for use in wood
stoves be fundamentally improved?
- 1.4 Is the use of manufactured fuel (densified
and wax logs) a credible emission
reduction
strategy? See Tables 1 & 2 .
- 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?
- 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?
- 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?
- 1.8 Are the emissions and efficiencies for
masonry heaters, based on in-home tests, shown in Tables 1 and 2
reasonable?
- 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?
- 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?
- 1.11 Have certified stove design and performance
improved since the first certified stoves? If so, how?
- State-of-the-art of fireplace emission control
technology.
- 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 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?
- 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?
- 2.4 What are the
distinctions between a masonry fireplace and a masonry heater?
- 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.
- 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.
- 4.1 Are the emissions and efficiencies for the
in-home use of pellet stoves shown in Tables 1 and 2 reasonable?
- 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?
- 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?
- Correspondence between in-home and laboratory emission
test results.
- 6.1 How accurately
do certification tests predict in-home performance?
- 6.2 How would you
design research testing in the laboratory to simulate in-home use?
- EPA Method 28 strengths and weaknesses.
- 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?
- 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?
- 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?
- Performance deterioration of EPA-certified wood stoves
in the field.
- 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?
- 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?
- Stress test pros and cons.
- 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?
- 10.2 Should a stress
test be made part of the certification process?
- Feasibility of developing separate emission factors for
dry and wet wood and for
softwood
and hardwood species classes.
- 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?
- 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?
- 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?
- 12.3 What would the key elements of routine
maintenance be?
-
end -
