This discussion made me curious about the actual amount of heat required to boil-off the water content of firewood, so I did some calculations: A BTU (British Thermal Unit) is the amount of heat required to raise 1 pound of water 1 degree Fahrenheit. Using an ambient temperature of 70 deg. F. (YMMV), it takes 142 BTU to raise a pound of water to the boiling point (at sea level) of 212 degrees. A cord of Red Oak, at 20% MC, weighs 3570 lbs. and contains 22.1 million BTU/ cord. http://chimneysweeponline.com/howood.htm The amount of water in a cord (20% of 3570 lbs.) equals 714 lbs. To vaporize that water: 714 lbs. x 142 BTU/lb.=101,388 BTU. This amounts to less than .5 percent of the total heat available. (101,388/22,100,000)x100=.458% So, yes, the amount of heat required to dry wood at 20% MC is insignificant. For that matter, the amount of heat required to dry wood at 30% MC is also an insignificant fraction of the total amount available. None of this has anything to do with the effect of the moisture content on the combustibility of the wood or creosote formation, it only describes the reduction of heat available.