It's time to start cutting wood for the winter of 2008!
That's right...18 months is what it really takes to get seasoned wood. Freshly cut wood is about 50% water whereas perfectly seasoned wood contains 15%-20% moisture. Lower moisture content allows the wood to burn at an acceptable rate while providing plenty of heat for your home. Too little moisture will allow your wood to burn too quickly and cause greater heat loss with the flue gasses and more airborne emissions.
SIZE REALLY DOES MATTER!
Cut, stack and cover your wood to keep the rain from soaking the wood but allow air to flow through it for better drying. Wood for your Greenwood stove will not have to be split unless it is too large to roll through the furnace door. 15" dia. x 16" - 17" long un-split logs work best since they will easily fit through the W100 which is 16" high x 18" wide.
Recent laboratory tests performed for Greenwood at an independent testing lab reveal the following differences between cord wood and 4x4's of the same species and moisture content:
Cordwood 4x4's
Wood Size (1) 15" dia. x 15" lg. (10) 3.75" x 3.75" x 22" lg.
Orientation in firebox Crosswise Lengthwise
Wood Weight 53.5 lb 62.4 lb
Burn Time 4.8 hr. 2.75 hr
Efficiency 85% 63%
Total Heat Output 450,000 BTU 333,000 BTU
Even though there was more wood weight in the 4x4's loaded into the furnace they burned quicker, less efficiently and with more emissions than the cordwood. The cordwood burned nearly twice as long and yielded 30% more heat than the 4x4's.
These tests continue to reinforce what we preach at Greenwood...burn only large rounds of un-split wood as long as you can roll it, crosswise, into your firebox. You will burn longer, more efficiently and cleaner with less work on your part!
THE BEST BANG FOR YOUR WOOD DOLLAR!
What kind of wood is best to burn? Well...the free wood that fell onto your property, as long as it is properly seasoned and the right size, is usually the best bet. But other than that if you have to purchase wood or recover windfalls from the forest floor the old rule-of-thumb that the heaviest, most dense wood is the best may not necessarily be true. Heavy wood could contain up to 50% water and be quite heavy but very low in heating value. But even more importantly, the composition of the wood may not be optimum.
This fact was recently acknowledged in reports published by the US Forest Service and the DOE as follows: The heat value of wood and bark fuel depends upon the lignin, moisture and extractive contents. This language was changed to eliminate the word density from the text. Density of wood does not directly correlate with energy value as shown in the following table.
SPECIES LB/FT 3 BTU/LB
Hickory 50.53 9,354
Oregon White Oak 44.83 8,113
Sugar Maple 42.20 8,145
Big Leaf Maple 34.09 8,400
Pitch Pine 33.84 12,214
Douglas Fir 31.96 9,048
Red Alder 23.70 7,986
The heaviest wood, hickory has excellent heating value but is only slightly better than Douglas fir. A relatively light wood, Pitch pine, has one of the highest heating values measured. Hardwoods such as Oregon white oak, and maple, while relatively heavy have lower heating values than some softwoods such as Douglas fir.
The best wood for your furnace is going to be seasoned for 18 months and cut in large rounds that will easily roll through the furnace door. The heating value of that wood is another story altogether. Make certain of the species and heating value especially if you are paying for wood or expending energy to recover it from the woods.
