[Greenbuilding] firewood moisture content - a question for Norbert perhaps

Frank Tettemer frank at livingsol.com
Sat Dec 17 11:16:17 PST 2011


Hi all,

Just checking in on this discussion as well. This is great stuff, and 
right to my heart.

I agree with Corwyn's comments, and can verify that if stuck with having 
to burn wet wood, splitting it finer than usual, and burning it hot will 
result in good heating and lower opportunities for creosote 
accumulation.  I consider wet wood as anything moister than 15%, (here 
in a moderately moist climate zone).  To achieve 15% or less, I dry the 
wood, in full sun, in single or double rows at the most, under scrap 
roofing steel, or other water-shedding materials for a two year period 
before burning.  This usually dries the wood to about 17% to 20% 
moisture. In Autumn, before the rainy season, I bring the wood into my 
wood shed for the reduction of it's last 5% of moisture.

As this may seem to create more work, I've had to really evaluate that. 
What I've found is, that if you get your wood piles going, with two 
years worth of wood, then you will have no problems if you're overtaken 
by calamity, i/e., back injuries, sickness, broken bones, etc.  What I 
learned from the old-timers in our area is that getting ahead, two 
year's worth, is like money in the bank. Over two year's passage of 
time, the price of wood will go up. So right off the bat, you are 
investing in your fairly-immediate future, and saving money.

The other advantages of very dry wood are that the house receives more 
BTU's per cord of wood. This results in less wood to bring in, and fewer 
ashes to take out.  Also, there will be less wood burnt each year, thus 
saving more money.  As well, it is much easier to kindle dry wood, so 
using dry wood makes life a lot easier.  The stove controls are more 
responsive, the cookstove oven comes up to temperature easier, and even 
an older model stove handles like a good sports car.

Thank you, Norbert, for once again offering my friend and neighbour's 
website link, at woodheat.org. John Gulland has had roving workshops 
through out Central Ontario, including a "burn trailer", with two 
different actively-firing woodstoves on the trailer, to see various burn 
cycles, and the affects of different makes and designs of wood stoves.  
His presentations are called "Burn It Smart".  Even older, 
stuck-in-their-ways woodburners, who already know Everything about 
burning wood, come away with greater understanding, going home to split 
their wood a bit finer, and burn their fires hotter, but for a shorter 
length of time.

John Gulland is responsible, collaboratively with a few others, for the 
excellent technical writing of Ontario's stove and instalation 
requirements.  His work, and the resulting codes, have saved countless 
homes from burning down.

I also recommend his newer addition:
http://www.woodheat.org/woodpile/
This is a discussion group, and there is enough questions and answers in 
it, to fill a book, coming from all sorts of novice and experienced wood 
burners.

Cheers,

Frank Tettemer
Living Sol ~ Building and Design
www.livingsol.com
613 756 3884


At 10:43 PM 17/12/2011, Norbert Senf wrote:
Interesting discussion, I haven't had a chance to check the list as 
regularly these days.
Something really interesting that I only learned recently is that tar 
(creosote) is only formed by smoldering combustion, which is without 
flames. On the other hand, soot is only formed by flaming combustion.
You can have both types of combustion happening at the same time, in 
different parts of the firebox.

Dry wood burns faster (hotter) and small wood burns faster (hotter). If 
you restrict the air supply, wood will burn slower (cooler), and can go 
from flaming to smoldering. Wood with 25% moisture can burn clean, if it 
burns fast enough. You can burn cleanly with even an old-tech stove by 
burning with the air supply wide open. The problem is with matching the 
heat output of the stove to the requirement of the house.

A good way to tell is if your chimney stays clean, like Corwyn's. 
Burning wet wood, he might still be able to keep it clean if he is able 
to burn the wood hot enough by using smaller pieces, burning with the 
air wide open, etc.

Nothing beats dry wood (20%), it just makes the job so much easier. You 
pretty much need to have a woodshed, and get your wood in there a year 
ahead of time.

Probably the best resource on the web on how to burn a stove is John 
Gulland's woodheat.org website:
http://woodheat.org/

Best ...... Norbert

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