Wood Heat: Choosing the Best Firewood for Your Wood-Burning Furnace

| 10/3/2013 12:00:00 AM

Tags: firewood, wood-burning furnace, Thaddeus Christian, hardwood, wood heat,

The Best Part of Winter!

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.

Photo By Fotolia

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 .

10/11/2013 9:10:17 PM

I've been burning various species for 12 yrs now in a wood stove. To reply to RobertE, most species have the heartwood burning longer/better the the sapwood (sourwood I've found to be an exception). When I season the wood, sapwood usually becomes softer and the heartwood harder. The best wood I've ever burned for heat is pecan, but that's a rare find. I currently burn dead dogwood that comes close to it, it's better than the oak and hickory available. I have lots of the dead dogwood because of the chanker that has been steadily killing trees. It's sad, but a great source of firewood.

10/11/2013 12:42:18 PM

One thing about burning soft woods, don't, unless it is for kindling. The amount of creosote soft woods create will cause a chimney fire much faster than hard woods. Oh, in contrast to the first sentence, you should have thought about splitting this year's firewood last year so it has proper time to dry enough to produce more heat more efficiently, and cut down on creosote.

10/11/2013 11:47:18 AM

A question for Thaddeus or others, a tree truck has heartwood on the inside and sapwood around it just inside the trunk. It is my belief that the heartwood will turn into longer lasting coals (for grilling or heating) than the sapwood. I am thinking about oak but the same would apply to other species of tree. I haven't seen anything that confirms or rejects this. Anyone have any thoughts on this?

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