Wed, 16 Mar 2005

A Classic fire

We heat our house with a Classic outdoor wood stove. It keeps the bark, bugs, dirt, and ashes outside, while providing us with a renewable source of heat. We fill it once a day, even in the coldest weather (-30F). About every two months it needs to be emptied of ashes. I let it burn down, stir it, burn down, stir, etc. Takes about a day for the fire to die down if you give it no fuel. Today was one of those days.

There's a bit of a trick to feeding the furnace. First, you need to be careful not to throw a log so it covers the air intake hole. If you do that, all that happens is you get hot wood; no air, no combustion. Second, you also need to not cover the ashes with the flat part of the wood. When you're refilling the furnace, it typically has coals buried in the ashes. A good stir will bring them up, but if you bury them underneath the wood, you'll just put them out and the fire won't catch. To keep a fire going, you need to make sure that the air circulates around the wood. I make sure that the bottom layer is laid pointy end down, so that the coals will heat up the exposed face of the wood.

The same applies to starting a furnace emptied of ash. I start with a pair of logs split at right angles. I put them with the flats down so that the remaining split face faces the other, about 3" apart. Bridging those two goes a thinly split strip of wood cut in half. It's cut in half because otherwise it's too long and hangs over the edges of the pair of logs. If it hangs over the edges, they'll shift when you put more wood in. Into the space between the logs, I put some cardboard curled up. If you leave the cardboard flat, it doesn't have enough fuel and it can fall flat, which prevents air from getting to it. On top of the cardboard I laid a bit of Christmas tree saved for firestarting purposes. On top of that I placed several dead coals I found in the ashes I had cleaned out. They have a fair bit of heat left in them and they're quite combustible. And into and around the cardboard I placed strips of birch bark I pulled off some of the logs.

Can you tell I was a boy scout when I was young? Needless to say, with all that preparation, the furnace fire lit with one match.

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