United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S7-90/019 Jan. 1991
EPA Project Summary
Field Performance of Advanced
Technology Woodstoves in
Glens Falls, NY, 1988-89
Stockton G. Barnett
Participate emissions trends were
evaluated for three models of catalytic
and two models of non-catalytic
woodstoves under "in-home" burning
conditions during the 1988-89 heating
season in Glens Falls, NY. The results
(averaging 9.4 g/h and 9.4 g/kg) showed
about a 55% reduction in emissions
compared to conventional woodstoves
and demonstrate that the emissions per-
formance of new woodstove technolo-
gies has improved compared to that of
stoves in earlier field studies. Emissions
for the non-catalytic stoves were about
50-55% and for the best performing
catalytic stove about 80% lower than
conventional woodstoves. Two of the
catalytic stove models displayed el-
evated emissions; in one case, a signifi-
cant degradation trend developed; and
in the other, emissions were elevated
throughout the test period. Leaky by-
pass systemsappearto be a major cause,
a> well as catalyst deterioration result-
ing from lack of flame shielding and
inadequate air/fuel mixing. Field emis-
sions, exceed laboratory certification
values on average by 2.5 times, but this
ratio varies considerably among the
stove models. Causes of these discrep-
ancies include quality control problems
with tolerances in production stoves,
emissions deterioration over time, and
inadequacies in stove design introduced
asthe result of attempts to design stoves
to pass a certification test which utilizes
conditions different from those en-
countered in the field.
This Project Summary was developed
by ERA'S Air and Energy Engineering
Research Laboratory, Research Triangle
Park, NC, to announce key findings of
the research project that is fully docu-
mented In a separate report of the same
title (see Project Report ordering Infor-
mation at back).
Introduction
This report summarizes results from par-
ticulate emissions tests cpnducted on five
woodstove models in homes in Glens Falls,
NY, during the 1988-89 wood-burning sea-
son. With the introduction of the catalytic
combustor for use in woodstoves by Corn-
ing Glass Works in 1980, the production of
clean-burning woodstoves appeared fea-
sible. Research and regulatory activity aimed
at producing low-emissions appliances in-
creased rapidly for both catalytic and non-
catalytic designs. Since woodstove devel-
opment and evaluation activities were
generally conducted under laboratory con-
ditions, the effectiveness of laboratory-
certified clean-burning technologies under
real-world in-home conditions was unknown.
More recent research efforts have been
directed toward evaluating in-home perfor-
mance.
Findings of the 1988-89 study include:
• The overall average particulate emis-
sions from the new technology
• woodstoves was 9.4 g/h (9.4 g/kg). This
represents a 55-60% reduction in emis-
sions compared to the 21.3 g/h rate for
Printed on Recycled Paper
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conventional stoves measured in earlier
field studios, and demonstrates that cur-
rent technology is capable of significantly
reducing particulate emissions from
woodstoves.
> The overall average burn rate was 1.09
dry kg/h, average wood moisture was
27% dry basis (21% wet basis), and
average draft was -0.074 in. water col-
umn (249 Pa). Average stack oxygen
was 15.4%, and net thermal efficiencies
ranged from about 48 (Country Comfort
CC150)to 67% (Country Flame BBF-6).
1 The woodstove model with the lowest
emissions, the catalytic Country Flame
BBF-6, had average emissions of 4.6 g/h
(4.1 g/kg), approaching the 1990 EPA
certification limit of 4.0 g/h (Figure 1).
These emissions are about 80% lower
than those of conventional woodstoves.
> The emissions of the other four stove
models appear statistically to constitute a
single population, about twice as high as
the Country Flame's.
• The two brands of non-catalytic stoves,
the Regency R3/R9 and the Country
Comfort CC150, averaged 9.3 g/h (8.2 g/
kg) and 11.3 g/h (11.2 g/kg), respectively.
These values are about 50% lower than
those for conventional stoves, and are
higher than the 7.5 g/h 1990 EPA certifi-
cation limit for these stoves.
• Two of the three catalytic stove models
did not perform up to expectations in
most homes tested. In four out of five
homes, the Blaze King Royal Heir expe-
rienced a significant trend in perfor-
mance degradation which began after 1
month of stove operation. The Oregon
Woodstove displayed generally elevated
emissions performance throughout the
test period.
Conclusions "
Examination of the stoves during and
after the emissions testing period revealed
the failure of a small number of identifiable
components as the cause of emissions
degradation, and identified areas of poten-
tial premature component failure.
1. Blaze King Royal Heir 2200 (catalytic):
Warping of some bypass support ar-
eas developed, causing leaks around
the catalyst. Partial catalyst failure
probably occurred in some stoves, in-
duced, at least in part, by lack of flame
impingement shielding and high inter-
nal catalyst temperatures.
Z.Oregon Woodstove (catalytic): By-
passes generally fitted loosely, caus-
ing leaks around the catalyst. Bypass
control mechanisms would not close
the bypass consistently.
3. Regency R3/R9 (non-catalytic): Some
baffles oxidized and/or warped.
4. Country Comfort CC150 (non-cata-
lytic): Oxidation and warping of bypass
sypBPjtjireasjoccurred.____
In general, several aspects of stove de-
sign should be followed to ensure a long-
lasting, clean-burning woodstove:
•\.Catalytic Stoves: Bypasses and by-
pass supports must be of sufficiently
heavy construction to resist warping
I
I
14-
13-
12-
11-
10-
9 -
8-
7 -
6 -
5-
4 -
3-
2-
1 -
0
12.5
11.4
9.8
4.6
9.2
~7
,-,=,-.<... . ,..~-. „ ». 1 " " T ,~
Country F. Blaze K. Oregon Regency
Stove Brand
11.4
V7
CC150
CC W/O Bobst
FJguro 1. Average emissions for all test runs by stove brand.
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and oxidation. The catalyst should be
flame-protected and large enough to
minimize internal peak temperatures.
Air and fuel must be thoroughly mixed
toproduceevencatalysttemperatures,
and the stove should be tuned as rich
as possible to reduce peak catalyst
temperatures.
2. Non-catalytic stoves: Baffles and other
internal parts must be able to resist the
oxidation, warping, and crumbling
caused by high temperatures. If it is
necessary to use a bypass, the guide-
lines for catalytic stoves apply.
In-home performance of four of the five
stove brands did not agree closely with the
certification emissions values, exceeding
those values by up to four times as much.
On the other hand, the EPA-weighted certi-
fication emissions values and the results for
the in-home tests on the remaining stove
brand, the Country Flame BBF-6, were
nearly identical.
In-home burning conditions produce
stack gases that are about twice as diluted
as those produced by the Douglas fir cribs
used in the certification tests. In-home
drafts are almost twice as high as those
experienced in the certification process.
These differences appear to have a nega-
tive impact on new stove designs since
such designs are developed to produce low
emissions underthe certification conditions.
A computer emissions model was devel-
oped for the non-catalytic stoves. Emis-
sions tend to be lowest when average burn
rate is high, stack draft is high, and wood
moisture is low.
A relatively high average net thermal ef-
ficiency of 67% was attained by the Country
Flame BBF-6 stoves. Efficiencies of about
50-55% (similar to those of conventional
stoves) were common with most non-
catalytic stoves, primarily as the result of
relatively high levels of excess air and high
stack temperatures.
Conclusions cannot be drawn at this time
regarding the comparative performance of
the two catalyst brands used in the study
(Corning and Panasonic). Sample size is
small and performance from stove to stove
is too varied.
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S. Bamettis with OMNI Environmental Services, Inc., Beaverton, OR 97005.
Robert C, McCrtllls is the EPA Project Officer (see below).
The complete report, consists of two volumes entitled "Field Performance of Advanced
Technology Woodstoves in Glens Falls, NY, 1988-89:"
"Volume l"(OrderNo. PB 91-125 641/AS; Cost:$17.00, subject to change)
"Volume II. Technical Appendices" (Order No. PB 91-125 658/AS; Cost:
$31.00, subject to change)
Both volumes of this report will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental
Research Information
Cincinnati, OH 45268
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EPA/600/S7-90/019
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