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

Reuben Deumling 9watts at gmail.com
Mon Dec 12 21:33:20 PST 2011


On Mon, Dec 12, 2011 at 8:19 PM, Sacie Lambertson <
sacie.lambertson at gmail.com> wrote:

> What is the stove you or Reuben use

 Mine is a Morso 2B from the mid-eighties. I was familiar with the larger
and less finicky version of this, the 1BO most of my life. I was not at
first taken by this smaller fellow, though I've come to think it is the
perfect stove--I love it. The firebox is much smaller than on the 1BO, the
vent much more determinative of a happy or unhappy fire. The 1BO is a
Clydesdale; this one's a racehorse.

> and what is the space you heat that allows just one or so burns a day?

My house is by most US measures small. 660 sq ft.


> I am presuming good insulation.
>
I have now completed a very careful insulation job on this 1894 shack: the
walls are 2x4 and have cellulose in them. Under the floor are R-30
fiberglass batts, and in the attic I laid two perpendicular layers of
fiberglass batts. Not sure about the R-value up there. The trouble are the
perimeter transitions where I am unable to get insulation where the rafters
meet the top plate. This is not the final word on insulating this house and
will be augmented one day. Corwyn's house specs are my holy grail.

>
> And what is it you do to create a very hot fire from the beginning--would
> appreciate the specific times involved in each step when you describe your
> process.  Starting from coals of the night before....or from scratch...
>
I do everything to do with wood heating exactly opposite from what I
learned as a kid, not because I'm rebelling but because what we used to do
makes no sense (to me today).

I now build what some people call a top-down-fire: two or three full size
pieces of oak; then some fir kindling, then three bundles of scrunched
newspaper. I use a lot of newspaper. I light it and close the door with the
vent all the way open. There are no coals to utilize, ever.
After about fifteen minutes I add a small piece of wood. Vent still open
all the way. After twenty to thirty minutes the flue gas thermometer's
temperature has climbed to 600F, my objective. I then close the vent a bit,
adding to the fire, raking the partially burned pieces of oak to the front
and adjusting the vent such that I can maintain the 600F indefinitely. It
takes poking, but after about 1-1/2 to 2-1/2 hrs I let the fire go out
because the house has come up to temperature.

This morning, for instance, it was 25F outside and 59F in my home office.
After my 2-1/2 hr morning fire the office was at 66F. When it is cold (by
our mild standards: 32HDD today, out of an annual 4,300 or so) I will make
another fire for about an hour or so in the evening to top things off, get
the indoor temperature back to ~66F.
The reason there are no coals is that my fires are discrete events. The
evening fire may be over by 7:30pm and I won't make a morning fire for 12
hours. This is the only and I've come to think trivial downside to this
method: no coals to help get the morning fire started.

I burn 1-1/2 cords of white oak per winter, and even with the insulation
the heating season still lasts from Oct. 15 to ~May 15. Last winter the
total number of hours our stove had a fire in it was 460, or 2.5 hrs/day on
average.
Although I love to heat with wood, I have planned to add Larsen trusses to
our shack and another 7-8" of cellulose. But I first have to learn to make
windows with wide/deep jambs. With that I hope to get our annual firewood
consumption down to about 1/4 of a cord (number completely made up).

I performed this same heating regimen for three winters before we had
insulation in the walls or under the floor, and it was tough going. Our
present circumstances are positively luxurious. The average morning indoor
low temperature in January used to be 54F before insulation. Now it is
59.5F. Now, even with the East wind blowing (a Portland wintertime
phenomenon which is no fun) we can achieve pretty much any desired indoor
temperature in a predictable fashion.

As for creosote, before I took down my brick chimney and replaced it with a
Metalbestos flue, and got my dry supply of firewood all dialed in, we had
some buildup in the stove pipe. I cleaned it every few hundred hours of
heating. But with the dry firewood (I think it has been ~17% moisture) I've
not seen any reason to clean it for the past year. There's about 3/8" of
ash on the stove pipe walls but that's it. With dry wood and hot fires that
come up to temperature quickly, there is no visible smoke coming out of my
chimney after 15-20 minutes. And the smoke that comes out in the first few
minutes is white. My neighbors who were none to pleased with our first
efforts at burning wood seem fine with it. I'm not even sure they notice
when we have a fire. And we live cheek by jowl here. Our lot is 33' wide.
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