I made that recommendation a little tongue in cheek to point out that
there are a lot of junkers out there, the beautiful Vermont Castings
stoves notwithstanding. If you know what you are doing, you can burn a
lot of the old stoves fairly cleanly - a good indicator is the absence
of flue deposits.
The issue with wood burning is smoldering, or non-flaming combustion. A
given stove/fuel system exhibits a "critical burn rate", at which point
the fire switches over from one mode of combustion to the other. The
problem is that the emissions rate, particularly for the nastier
polycyclic aromatics, can be 2 or more orders of magnitude higher in
smoldering mode than in flaming mode - you can burn 100 or more clean
stoves with the same environmental impact in terms of airborne
carcinogens (quite similar to cigarette smoke, actually) as a single
"stinkpot" stove/operator system.
Basically what the EPA stoves have accomplished is to reduce the
critical burn rate - you can turn the stove down a lot more before it
burns dirty. This can be a particular problem with newer, efficient
housing, where the average heat demand can be quite low for long
stretches of time - a large pre-EPA Vermont Castings stove simply has a
very hard time targeting a 1 or 2 or 3 Kw output (of course, you could
always add some storage, as you need to do with solar - a renewable that
is very closely related to wood. Water is one way to do it, as long as
you don't have too much heat exchanger directly cooling the fire -
better to insulate the firebox and use the hot products of combustion
instead). If you're heating a big drafty farmhouse, on the other hand, a
pre-EPA stove often works just fine and the pipes can stay quite clean
if the operator knows what he/she is doing. For Mr & Mrs Average, the
EPA stove gives them a much wider margin for error.
My retrofit expertise doesn't extend into the airtight stove realm,
unfortunately. A good site to check is www.hearth.com. Heating domestic
hot water with wood should be utilized a lot more widely - as you know,
Marc, it is quite easy to do. According to Energy Probe, a Toronto think
tank, a single electric hot water heater in Ontario (which is 60%
nuclear) generates 200,000 lethal doses of plutonium annually. Anyone
care to venture an environmental impact comparison?
Best.........Norbert
-----------------------------------------
Norbert Senf--------------------email:---mheat@mha-net.org
Masonry Stove Builders-------------------mheat@hookup.net
RR 5, Shawville-----------------website: http://mha-net.org/msb
Quebec J0X 2Y0------------------fax:-----819.647.6082
--------------------------------voice:---819.647.5092
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