Your involvement with the processing of your firewood determines just how much money you save. The more you do, the more you save. Buying firewood that is cut and split may offer little savings over conventional heating, however cutting your own wood can lead to significant savings. Befriending a local tree trimming service can provide a free source of tree trunks, even to an urban or suburban wood burner. The home heating veterans at Woodheat.org write that the best firewood is the one that is closest to you. Different species do offer different burn characteristics, however.
"Softwood" and "hardwood" generally refer to conifers and deciduous trees respectively. When you start cutting and splitting them, however, you find that not all conifers are soft and not all deciduous trees are hard. The light softwoods such as fir, spruce, white pine, white cedar and western red cedar offer low heat per cord---between 15 and 17.5 million BTUs. In their favor, they light easily, burn quickly and leave little ash. They're a good choice for early season fires and to mix with dense hardwoods in the coldest part of the season.
Low density deciduous trees offer little to the wood burner. If plentiful while dense hardwoods are scarce they may prove your best option, but will require more frequent reloading of the firebox than other choices. Aspen, box elder, basswood, poplar, butternut and cottonwood make up this group, offering the lowest output of all, between 12.5 and 17 million BTUs per cord.
Eastern red cedar, southern yellow pine, and short leaf pine are dense softwoods that offer 19 to 20 million BTUs per cord. They burn hot and fast and leave little ash. Damper control is critical with these woods, as is curing. Seasoned for six months to a year, they make good firewood, but will lead to creosote build up in the flue if burned green.
Soft maples, elm, cherry (and other fruit woods), sweet gum, birch and ash are hardwoods that offer more energy than most other choices and can be obtained in volume from tree services. These are trees that are commonly used in landscaping, and large urban-grown trees have no commercial value as lumber. Many tree services have to pay to dump the trunks of trees they remove. If you have easy access for their trucks, most will gladly supply you with all you can handle. These trees offer between 18 and 24 million BTUs per cord.
Very Dense Hardwoods
Red oak, white oak, hickory, beech, black locust and osage orange are the heavy hitters. This is the group you want, if they're native to your area and can be obtained easily. If you're buying firewood, these will command a premium price, but return the investment with better performance. They will deliver between 24 and 31 million BTUs per cord. These species need to be seasoned for close to a year (if not more) for peak performance.
- Photo Credit firewood image by Nikolay Lapitsky from Fotolia.com
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