Poindexter
ArboristSite Operative
Went to the symposium today co-sponsored by the University of Alaska at Fairbanks and the Yukon Valley chapter of the Society of American Foresters.
One thing I finally understand is the difference between expressing the moisture content of wood on a wet basis versus dry basis. I just couldn't quite really get my head around it. One speaker explained with a piece of wood that weighs five pounds right now. Its four pounds of cellulose and one pound of water. Compared to the wet weight of the wood - five pounds - the one pound of water is 20% of the weight of the wood piece, this is wet basis. Dry basis, compared to the dry four pound weight of the wood in the piece the one pound of water represents 25% of the weight of the dry wood.
All the electronic moisture meters they know of calculate on dry basis, so when I stick my probes in a split and it reads "25%" (dry basis), I now know the same piece of wood is at 20% (wet basis) and therefore seasoned enough to go in my EPA cert stove- because the stove manufacturers are looking for 16-20% moisture content wet basis.
That was cool to learn.
The whole shindig was aimed at folks new to or thinking about wood burning, so some review for me. A lot of time talking about your homes "HHI" or Home heating Index. I was thinking about all y'all down south getting hammered with cold weather this season and tried to pay attention. Really HHI boils down to how good your air seals are and how thick your insulation is. A super tight house with really thick insulation has a low HHI - takes fewer BTUs to maintain a given temperature, a leaky house with thin insulation takes more BTUs to maintain the same temperature. Intuitively obvious, but they got right down into the math. My personal HHI is about a six, moderate for Alaska, excellent for the lower 48.
I finally got a grip on HDD, or heating degree days too. If your average temp in a 24 hour period is +65dF, then you accumulated zero heating degree days that day. If the average temperature in 24 hours is zero degrees Farenheit, you accumulated 65 HDDs that day.
Thirty year trailing average for Fairbanks is 13,666 HDDs annually. We are averaging 1872HDDs in November, 2141 in December, 2260 in January and 1858 in February.
For comparison, Minneapolis in January 2013 had 1482 HDDs, for January 2014 I'm finding 1762HDDs, typical numbers for Fairbanks average October and November. I did find a HHI estimator online here: http://www.nhsaves.com/homeheating/ , but it errored on my not valid NH zipcode.
A bunch of time on firewood seasoning too. Local we get little rain but have damp earth, our two prime directives are get it off the ground and get it covered on top- with math and pictures with circles and arrows and all the rest at this one.
All in all a good day. I did win a fuel value calculator as a doorprize. I spun the wheel to $5.03/ gallon for propane. Assuming 95% propane efficiency an air dried cord of firewood in a 70% efficient wood stove is worth $700. Break even price for coal in a 50% efficient coal stove is $911/ ton. Or you could break even on natural gas at $57.40 for 1000cf. Jeeeeezz that's a lot of money. Felling my own on state land a cord runs me about $80 c/s/s/c at the house, allowing for truck fuel, saw maintenance, splitter fuel, the whole nine yards.
FWIW I last paid $3.86/ gallon for #2 heating oil, my break even price for a cord of air dried wood is $511.60, so every cord I burn is $431.60 for my time.
One thing I finally understand is the difference between expressing the moisture content of wood on a wet basis versus dry basis. I just couldn't quite really get my head around it. One speaker explained with a piece of wood that weighs five pounds right now. Its four pounds of cellulose and one pound of water. Compared to the wet weight of the wood - five pounds - the one pound of water is 20% of the weight of the wood piece, this is wet basis. Dry basis, compared to the dry four pound weight of the wood in the piece the one pound of water represents 25% of the weight of the dry wood.
All the electronic moisture meters they know of calculate on dry basis, so when I stick my probes in a split and it reads "25%" (dry basis), I now know the same piece of wood is at 20% (wet basis) and therefore seasoned enough to go in my EPA cert stove- because the stove manufacturers are looking for 16-20% moisture content wet basis.
That was cool to learn.
The whole shindig was aimed at folks new to or thinking about wood burning, so some review for me. A lot of time talking about your homes "HHI" or Home heating Index. I was thinking about all y'all down south getting hammered with cold weather this season and tried to pay attention. Really HHI boils down to how good your air seals are and how thick your insulation is. A super tight house with really thick insulation has a low HHI - takes fewer BTUs to maintain a given temperature, a leaky house with thin insulation takes more BTUs to maintain the same temperature. Intuitively obvious, but they got right down into the math. My personal HHI is about a six, moderate for Alaska, excellent for the lower 48.
I finally got a grip on HDD, or heating degree days too. If your average temp in a 24 hour period is +65dF, then you accumulated zero heating degree days that day. If the average temperature in 24 hours is zero degrees Farenheit, you accumulated 65 HDDs that day.
Thirty year trailing average for Fairbanks is 13,666 HDDs annually. We are averaging 1872HDDs in November, 2141 in December, 2260 in January and 1858 in February.
For comparison, Minneapolis in January 2013 had 1482 HDDs, for January 2014 I'm finding 1762HDDs, typical numbers for Fairbanks average October and November. I did find a HHI estimator online here: http://www.nhsaves.com/homeheating/ , but it errored on my not valid NH zipcode.
A bunch of time on firewood seasoning too. Local we get little rain but have damp earth, our two prime directives are get it off the ground and get it covered on top- with math and pictures with circles and arrows and all the rest at this one.
All in all a good day. I did win a fuel value calculator as a doorprize. I spun the wheel to $5.03/ gallon for propane. Assuming 95% propane efficiency an air dried cord of firewood in a 70% efficient wood stove is worth $700. Break even price for coal in a 50% efficient coal stove is $911/ ton. Or you could break even on natural gas at $57.40 for 1000cf. Jeeeeezz that's a lot of money. Felling my own on state land a cord runs me about $80 c/s/s/c at the house, allowing for truck fuel, saw maintenance, splitter fuel, the whole nine yards.
FWIW I last paid $3.86/ gallon for #2 heating oil, my break even price for a cord of air dried wood is $511.60, so every cord I burn is $431.60 for my time.
As I learned form your first post, that's measured on a "dry" basis, and so it's not as bad when you convert to a "wet" basis, but it was still too wet to burn effectively. 
