A cord is a stack of wood 4 feet high, 4 feet wide and 8 feet long. Allowing for air pockets, a cord is approximately 85 cubic feet of wood.
On average, a pound of wood produces 8,600 BTUs of heat, regardless of species. So dense heavy woods deliver more heat per cord. Consider this fact when comparing prices for different kinds of wood.
It takes about 1,000 BTUs to evaporate each pound of moisture in a log. That is why dry wood produces less creosote and 10-30% more useable heat for your home.
A good time to cut or buy green wood is in late winter or early spring. To dry it as quickly as possible, cut it to length and stack it so that air can circulate through the pile. Also, shelter the stack from the weather and hold it for 18 months before using.
If you cut your trees in the spring or summer, let them lie "unlimbed" until the leaves wither. The withering process draws moisture from the wood. Then, cut the wood to the longest length that will fit in the firebox. The longer the stick, the longer the fire will hold.
The amount of heat extracted from a cord of wood varies with the species. The U.S. Forest Products Laboratory compiled the following figures, showing weights and energy content for various species of wood. These figures assume seasoned wood with 20% moisture content.
|Wood Species||Cord Weight (lbs)||Energy Content (million BTUs/cord)|