Older thread, but somebody might find this useful. I built a small kiln in my shop (8x14 w/7' ceiling) that will hold 1,000 bdft easy. I use an old window AC unit for my heat source and dehumidifier. Simply sits on a shelf inside and drips in a bucket.
The room is very well insulated, and I used OSB to finish the inside, with a couple coats of mobile home roof coating (aluminum based) as a vapor barrier. I air dry my wood on sticks down to 20% or so, then put my cabinet/millwork/furniture stuff in the kiln and take it on down to 6-8%.
When I first start up the kiln, I have to run a small (1500w) electric heater to get the room up to enough temp (about 70) to get the AC to kick in, but from them on, the scrap heat off the AC unit will raise the room temp to 125-130 range.
Once you hit about 100-110, the moisture starts coming off the wood, and hitting the cold coil of the AC (yeah, it's cold, but unless you put your hand on it, you'd never know it ! ), condenses and drips in the bucket. I can get a 5 gallon bucket per 24hrs off a full load of 20% wood at first ...hard to believe there is THAT much water still in there !
One note....you DO want an OLD dog of an AC unit with R-12 in it. If it has R-22, I found about 105 degrees, the head pressure of R-22 is so much it locks the compressor up, and kicks the motor overload out. It will cool down and start again, only to repeat over and over....R-22 would not work for me. And I know nothing about the newer freons. Get yourself a chart out of an AC repair book, and see how the pressure compares to R-12 at about 130 degrees, and you'll know what works.
