With autumn dawning, it’s time to start thinking about splitting, stacking, and stoking. For folks using wood heat, especially with a wood-burning furnace, there is a lot of money to be saved (or wasted!) when selecting firewood types.
When buying firewood, the task is fairly straightforward. Denser, heavier wood will produce more heat, commonly measured in British Thermal Units, or BTUs. Hardwoods — notably oak, hickory, birch, apple, maple, and beech — will burn longer and hotter than their conifer cousins. These woods also have excellent coaling properties, which is to say, when burned they produce more coal than other woods, and these embers can stay hot through the long winter night. Some conifers may burn hotter than hardwoods, and may be easier to start, but they burn quickly, ultimately releasing fewer BTUs, requiring more logs and more attention. For example, a log of Sugar Maple will produce twice as much heat as an equally sized log of White Cedar. Save softer woods for burning at the beginning and end of winter, when heating requirements are lower. For the sake of trivia, here’s an interesting fact: One pound of any given tree species, hard or soft, will yield roughly the same amount of heat, somewhere in the neighborhood of seven thousand BTUs. The density of a given volume is the crucial factor for wood heat.
When harvesting firewood from your own property, there are additional considerations. Before you cut a stand of straight, proud trees, look at the merchantable board-foot content, that is, the volume of saleable timber! Don’t hastily drop a stately oak for firewood before calculating what it might be worth in a timber sale. There are probably better firewood candidates anyhow, like a knurled locust or a shaggy hickory that no one will want for lumber.
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Thaddeus Christian is an editor with MOTHER EARTH NEWS magazine. Right at the moment he is up to his knees in chickens, babies, and news articles. Find him on Google+.