Heat output is typically measured in terms of Btu output.
One Btu is the amount of energy required to raise one pound of water one degree Fahrenheit
Factors That Affect Btu Output:
1) The efficiency of the heating appliance burning the fuel.
2) Improperly set controls or no settings to control the combustion air required to burn the fuel.
3) All wood burning appliances Btu ratings are based on burning high quality dry wood such as birch, oak or tamarack! So if as with most people you are planning on burning White Poplar the output of would be approximately 75% of the outdoor furnace rating.
4) The potential Btu of the fuel being burned is also affected by up to 30% by the moisture content of the fuel supply being burned:
a)Heat is consumed in the evaporation of moisture, hence the more moisture in the fuel supply the less heat output (seasoned wood has 20% to 30% moisture content)
If the fuel is too dry, the heating appliance is not be able to ?capture? the heat as fast as it is being produced, so excess heat is exhausted out the chimney.
This effectively could reduce the wood burning appliance?s rated Btu output up to 50% depending on type of fuel being burned. (i.e. dry or wet white polar)
5) Any incomplete burn of fuel and particles.
(wood coals and charcoal are fuel burn them!)
Potential BTU output and costs of various fuel sources
(fuel delivered prices before any potential rebates as of 02/18/09).
|
Source |
Dry Btu |
Per |
Pounds Per |
Cost Per |
Bagging Cost |
Cost Per 1,000,000 Btu Input |
Appliance Efficiency |
Cost Per 1,000,000 Btu Output |
|
Wheat (#2 Soft) |
505,000 |
bushel |
60 |
$5.40 |
|
$10.69 |
80% |
$13.36 |
|
Wheat (Feed) |
505,000 |
bushel |
60 |
$4.80 |
|
$9.50 |
80% |
$11.88 |
|
Rye |
500,000 |
bushel |
60 |
$ |
|
$ |
80% |
$ |
|
Barley |
393,600 |
bushel |
48 |
$1.52 |
|
$3.86 |
80% |
$4.83 |
|
Oats |
264,000 |
bushel |
32 |
$1.94 |
|
$7.35 |
80% |
$9.18 |
|
Corn |
493,000 |
bushel |
56 |
$3.89 |
|
$7.89 |
80% |
$9.86 |
|
Natural Gas |
126,780 |
ccf |
$2.537 |
|
$20.01 |
92% |
$21.75 |
|
|
Natural Gas |
126,780 |
ccf |
$2.537 |
|
$20.01 |
80% |
$25.01 |
|
|
Propane |
24,300 |
liter |
$0.67 |
|
$ |
78% |
$ |
|
|
Fuel Oil #2 |
37,670 |
liter |
$0. |
|
$ |
80% |
$ |
|
|
Electricity |
3,410 |
kWh |
$0.1353 |
|
$39.677 |
95% |
$41.76 |
|
|
Charcoal |
25,000,000 |
ton |
|
|
|
75% |
|
|
|
Coal (Sub Bit) |
18,734,000 |
tonne |
2204 |
$56.25 |
|
$3.00 |
65% |
$4.62 |
|
Wood Pellets Bagged |
312000 |
bag |
40 |
$5.98 |
included |
$19.17 |
80% |
$23.96 |
|
Wood Pellets Bagged |
15,600,000 |
ton |
2000 |
$249.00 |
included |
$15.96 |
80% |
$19.95 |
|
Yellow Birch |
26,500,000 |
cord |
4142 |
|
|
|
55% |
|
|
White Birch |
21,710,000 |
cord |
3400 |
$83.33 |
|
$3.84 |
55% |
$6.98 |
|
Tamarack |
21,150,000 |
cord |
3300 |
|
|
|
55% |
|
|
White Poplar |
16,570,000 |
cord |
2370 |
$66.67 |
|
$4.02 |
55% |
$7.31 |
|
Spruce |
15,980,000 |
cord |
2314 |
$66.67 |
|
$4.17 |
55% |
$7.59 |
|
Pine White |
14,530,000 |
cord |
2272 |
|
|
|
55% |
|
cubic feet of space and containing 80 cubic feet of solid wood.