Im only burning wood for 3 years now but when I first started I questioned everything. I neither have the time or desire to cut or stack wood myself as my time is more valuable. Ive found very little scientific research supporting an optimum 20 % moisture content or that dryer is better. I did find the following :
http://www.fs.fed.us/pnw/pubs/pnw_rn450.pdf which supports my non stacking as just as effective as stacking for drying wood. I have also found numerous studies that support a 3 month drying time in most areas as being sufficient. So in the interest of time and money, I dont stack but I do buy my firewood in March of each year and cover the pile with a tarp. Works for me:msp_thumbup:
From the U.S. Forest Service study (which is a study of drying wood using a solar kiln) which you referenced above:
"Unsplit paper birch cut to 16- to 18-inch lengths will not air dry to 20 percent moisture content in a single season. Any system that would accelerate drying to permit burning of dry wood the same year it is cut would be useful."
The clear implication being that 20% is the target number for suitable burning, if you can achieve close to that MC in 3 months, so much the better. The study also states:
"High moisture content in firewood results in less effective burning of the wood and in a loss of energy in evaporating the water during burning. A cord of paper birch (Betula papyrifera Marsh.) firewood with 15 percent moisture (dry weight basis) would be expected to use an energy amount equal to 470,000 British thermal units (Btu) during burning to evaporate this moisture. An equivalent cord of paper birch that had a moisture content of 80 percent would be expected to use 2.5 million Btu (Ince 1979). The dry cord will produce more than a 12-percent increase in usable heat."
No need to clarify that.
Regarding stacking, the study goes on to state:
"Each stack was about 18 inches wide, 8 feet long, and 5.5 feet high and contained approximately one-half cord. In two of the piles, individual pieces were oriented north-south and conventionally stacked. In the third pile, alternate tiers of pieces were oriented east-west to provide for better air circulation."
This clearly describes a single row of stacked wood (which the diagram also shows). Though they frequently use the word "pile", the pile they descibed was stacked. I did not find any reference to a pile, in the sense of a heap of wood with no organization or alignment of the individual pieces.
Again, this study was comparing drying stacks of green paper birch using a simple solar kiln as compared to air drying the same type of stack. They did not compare loose piles to organized stacks. I do NOT maintain that one dries better than the other. I do maintain that I can stack more wood in a given footprint than can be loosely piled in the same, which is frequently the reason for stacking.
Referencing scientific studies is only helpful if they studied and supported the methods you espouse.
I do not wish to convince you that your methods are wrong. If they work for you, that's all that counts.
However, if you wish to convince others.....