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Stovers:
Being in John's neighborhood,
and knowing of many valuable contributions that John Crouch has made to
"stoves", I visited John in Sacramento on the 17th. John's title is
Director of Public Affairs for the Hearth, Patio, and Barbecue Association - the
main trade association for North American wood stove businesses. I believe that
John's activities include a lot on emissions regulations established by the US
EPA. Although John's office is in California, the main HPBA office is near
Washington DC.
John suggested we meet at a
Sacramento stoves company called "The Solar Syndicate" - a store with a name
that doesn't capture their main business of stoves. There were dozens on
display - with many operating. John knew these stoves intimately and
especially on the changes each manufacturer had made to meet or improve upon the
US EPA standards. Apparently these stove manufacturers have mostly gone
away from their former approach of using catalytic converters - and now have
more clever means of introducing secondary air (many holes in 2, 3, or 4 tubes
along the upper stove ceiling).
The EPA standard is 7.5 gms per
hour (4.1 for stoves with catalytic converters) - with US manufacturers
achieving a better number - some down around 2. The numbers Tami gave in
Seattle were in units of gms per kg of fuel and I failed to record Tami's
numbers for the stoves she tested. John gave me a 1993 report done for the
Oregon Department of Energy showing results for many different stove and
(manufactured) fuel combinations. I haven't absorbed all that data
yet, but the EPA -approved stoves were about 10 times better on particulates and
3 times better on CO. Here are some summary numbers just for cord wood in
units of g/kg, g/hr, g/m3, g/Net MJ. Note the weight of CO was much
greater than the weight of particulates.
Particulates
Conventional uncertified wood
stove - 36.25, 40.07, 1.843, 3.57
EPA-Phase 2
Certified
3.73, 5.21, .244,
.35
Masonry
fireplace 25.7,
61.6,.125, >12.85
Zero-Clearance
Fireplace
19.36, 44.85, 0.077, >9.2
CO
Conventional uncertified wood
stove - 180.96, 200.03, 9.391, 17.84
EPA-Phase 2
Certified 56.36,
78.9, 3.698, 5.31
Masonry
fireplace 119.2, 285.5, 0.573, >59.58
Zero-Clearance
Fireplace
100.89, 233.7, 0.403, >47.92
The combustion efficiencies were
81.8, 94.8, 83.6, and 86.9 % respectively (with heat transfer efficiencies of
about 60% - for space heating - for the first 2 and about 10% for the latter
two).
The main body of the report was
then for many different manufactured fuels (artificial logs) - and they
were generally better than cord wood.
I mention all this
for several reasons: First, for Tami to compare her results for
the Rocket stove (presumably possible on all four bases)
Second, to see if anyone else
has simple cook stove numbers to report - so we can start developing a larger
data base.
Three, to point out the types of
data we collect will need more discussion. I am not sure which of the four
measures is best for our purposes.
Four, to call attention to the
store of knowledge that exists with the commercial stove manufacturers
(many in Europe) and the commercial certified testing laboratories - and with
John himself.
Five, to ask John and others who
are aware of this store of knowledge to amend this brief report.
John says that the manufacturers have spent a lot
of time tweaking their designs to pass the EPA tests. There are mandatory
loading protocols, with the harder ones to meet being those with low
loadings. The test protocol calls for a 15 foot chimney - which we will
rarely have - and the results for a stove with a different chimney height after
real-world installation can be very different. Also, there are EPA rules
for the separation (1.5 inches(?)) of the wood pieces from each other - that are
also apt to diminish the results when the fires are stoked by typical
homeowners.
At one time there were 6 labs doing these tests -
but the number is now down to three. In the early days of developing a
methodology, all 6 labs tested the same stoves - and they slowly developed skill
in getting similar results. Apparently the European standards are not as
well developed and so the North American standards are accepted in
Europe.
It was surprise to learn that
John lived in Colorado for many years. John thinks there is some hope for
getting some pro bono support from his industry - although most of the test data
is considered confidential. I could only glance at one test report for a
stove company now out of business.
John and Tami: any comments? (and
thanks to both for getting me started on the emissions measurements learning
curve).
Ron
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