[Greenbuilding] Wood is the #1 domestic renewable energy source in the U.S., by far

[Norbert Senf]

Hi Tim:

Yes, Washington State stoves must meet an 
emissions limit of 4.5 g/hr of particulate, 
whereas the current federal EPA limit is 7 g/hr. 
Both WA and EPA use a similar fueling and test 
cycle, and it is unavoidable that the numbers are 
dependent on the testing protocols used.
Some of the stoves are testing considerably under 
the limit. Actual "in home" numbers are a lot 
trickier to get and likely would be all over tha 
map, and you would need to take an average from a large sample of users.
Still, outdoor boilers are belching out in the range of 100 g/hr.

For masonry heaters, grams per hour is a 
non-sensical measure, since you put out high 
grams per hour for 2 hours, and then zero grams 
per hour for 22 hours. Grams per kilogram of fuel 
burned makes a lot more sense as an emissions 
measure, and is equivalent to g/hr when the burn 
rate happens to be 1 kg/hr, which is actually the 
average burn rate of the average stove in the US.

We can reliably get in the 1 g/kg range with 
masonry heater, with some of the latest 
technology from Austria doing about half that. 
Pellet stoves are in the same range.

Efficiency is not part of the EPA test protocol, 
even though all the data that would be needed is 
already collected for the emissions test. Most of 
the numbers you see are estimates. I'd venture 
70% +/- 10%. The theoretical maximum without 
going to a condensing system is around 84%. 
Additional confusion stems from European numbers, 
which are calculated to a different definition, 
and in the case of a European condensing boiler 
can be higher than 100%. Roughly, add about 9% to 
an American efficiency number for wood to convert to a European number.

If you don't transfer any heat from the connector 
pipe (as per your question), i.d. take a rough 
guess and say you are looking at 2% - 5%, 
depending on how high the burn rate is and how long the connector pipe is.

Norbert

At 03:05 AM 9/28/2013 +0000, candtcampbell at juno.com wrote:
>Norbert wrote, "Actually, you  can achieve
>virtually complete combustion with wood these
>days, and there are lots of new stoves that can
>do it." Mr. Senf, are you basically referring to 
>Washington State certified stoves? Among those 
>are there any you feel confident deliver about 
>80% of the wood's heat content to the room in which they are located?
>
>And a related question: Suppose one omits the 
>stove pipe and connects chimney pipe directly to 
>the stove. What percentage of the wood's heat 
>content would then be lost to the chimney?
>
>Tim
>
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-------------------------------------------
Norbert Senf---------- mheat(at)heatkit.com
Masonry Stove Builders
25 Brouse Rd.
RR 5, Shawville------- www.heatkit.com
Québec J0X 2Y0-------- fax:-----819.647.6082
---------------------- voice:---819.647.5092