RenovationGeorge said:
Thanks Battenkiller, for a great read. Very cool.
Yeah, I could get lost in all the good data I find on the Internet. A lot of the government stuff is hard to pass along on a board such as this because the clickable links all lead to direct downloads of PDFs. I have hundreds of similar documents stored on my computer from over 10 years of online research, but they are all in PDF format. Same in this case. I can't get a direct link to that PDF, but if you follow the link below, you can get the document by clicking the link at the top of the list:
EPA Emissions PDFs
The article listed right below that one is even more fascinating. It compares emissions as a function of burn rate, showing that low burn rates are dirtier than high burn rates
by a factor of 48 in hardwood like oak. The implication is that occasional burners and other folks who are burning at very low rates "just to take the chill out" are the worst offenders, pollution wise.
There is a huge sacred cow getting toppled in that study as well. You can see by the table below that at low burn rates, wood at 25% MC makes a bit more creosote than wood at 15% MC, but that trend reverses itself at higher burn rates. In fact, oak at 5% MC forms
almost 7 times as much creosote at high burn rates as wood at 25% MC. It appears that kiln-dried hardwood is a very dirty burn indeed. Also, dense hardwoods at 25% MC produces only half the creosote that is formed by burning wood at 15% MC. Of course, I expect to here a chorus of BS being called on this info. After all, it's only scientific data, not hardcore anecdotal evidence. %-P Would it help to add that this data was gathered during in-home testing?
Further down there is an article about net efficiencies. Right from the EPA's mouth, the older stoves average 54% net efficiency, whereas both cat and non-cat stoves average only 14% higher in net efficiency at 68%. As the footnote states, net efficiency is a function of both combustion efficiency and heat transfer efficiency. It is the heat you actually get released into your home. 54% ain't so bad when folks are constantly claiming the old stoves are more like 30% efficient, and that you'll half your wood usage with the same amount of heat just by switching to an EPA stove. Well, I've been calling BS on that notion for years now. Maybe I can get a job with the EPA. ;-)