Osburn 900 Installation and Operation Manual
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4.4.6
BUILDING DIFFERENT FIRES FOR DIFFERENT NEEDS
Using the air control is not the only way to match the wood fire’s heat output to the heat demand.
Your house will need far less heat in April than in July to be kept at a comfortable temperature. If
you fill the firebox full in fall weather, you will either overheat the space or turn the wood fire
down so much that the fire will be smoky and inefficient. Here are some suggestions for building
fires to match different heat demand.
4.4.6.1
Small Fires to Take the Chill Off the House
To build a small fire that will produce a low heat output, use small pieces of firewood and load
them crisscross in the firebox. The pieces should be only 75 mm to 100 mm in diameter. After
raking the coals, you can lay two pieces parallel to each other corner to corner in the firebox and
lay two more across them in the other direction. Open the air control fully and only reduce the air
after the wood is fully flaming. This kind of fire is good for mild weather when you are around to
tend the wood fire and should provide enough heat for four hours or more. Small fires like this are
a good time to use softer wood species so there will be less chance of overheating the house.
4.4.6.2
Long Lasting Low Output Fires
Sometimes you will want to build a fire to last up to eight hours, but don’t need intense heat. In
this case use smaller pieces of hardwood and place the logs compactly in the firebox so the pieces
are packed tightly together. You will need to fire the load hot for long enough to fully char the log
surfaces before you can turn the air down. Make sure the fire is flaming brightly before leaving the
fire to burn.
4.4.6.3
High Output Fires for Cold Weather
When the heat demand is high during cold weather, you’ll need a fire that burns steadily and
brightly. This is the time to use your biggest pieces of hardwood fuel if you have it. Put the biggest
pieces at the back of the firebox and place the rest of the pieces compactly. A densely built fire like
this will produce the longest burn your wood fire is capable of.
You will need to be cautious when building fires like this because if the air is turned down too
much, the fire could smoulder. Make sure the wood is flaming brightly before leaving the fire to
burn. The wood should be positioned in a north/south fashion, that is, from the front to the back
of the firebox.
