I work for a rather large company that produces Charcoal,firewood,chips,chunks, and fire logs. I believe I can help you with your problem. I am unsure of what temps you can reach with your heating system but I will throw some numbers out. To achieve 25% moisture in 24ton cycles in a 40hr period we input 280 degrees with 70cfs air flow. We usually dry in the neighborhood of 1000T per year and I am sure you can pull back the heat and air flow to accomplish your drying needs. Our wood sizes vary as well coming thru a KordKing but you can usually figure on 40hrs for 24T. If you are drying 5T or less at a time I used a tight insulated structure that makes reaching 140 degree ambient temp easily done with a oil or gas burner with the forced air blowing in thru the bottom of one wall. Now this is the tricky part. You need to make a curtain ran in the same direction as your stacks.Attach it to the ceiling and laying on the wood to force the air flow through the wood an not allowing it to pass over. Also you need to install two baffle gates one on either side of the building high up on the walls. Switching the open/closed sides ever 8 to 10 hrs. This should dry 5T in 72 hrs. For mine that I built I purchased an Amish built portable barn 10x12 and insulated it with fiber board. Used a oil burner from a local garage that had closed down and burned used motor oil which was happily donated by the community. Its EPA approved and efficient. I built a heat channel made of metal duck work to run 15 feet to the inlet of the building. In the summer months I can hit 170. I installed a couple of spark screens that I purchased from the local fireplace store as fire safety. I have noticed it takes us(me,wife ,kids, and any neighborhood kids who show up and are bored enough to help) about the entire cycle time to haul in saw up split and have ready for the dryer 5T for the next cycle. My company uses this exact set up with saw mill slab wood for the production of Charcoal. Works awesome brings 60T of wood down to 10% or less in 50hrs at 375degree. There is of coarse some much bigger heat and air sources but the same concept.:thumbsup: