Dehumidifier Kiln Chamber Size

A discussion of constructing the drying box to fit the dehumidifier capacity and the intended lumber dimensions and quantity to be dried. October 26, 2011

Question
I purchased a DH Kiln (it will dry up to 4000 BF per charge) and now I'm ready to build a chamber. I am not sure around what would be the right size. I want to dry 16' 6" and 12' 6" boards. Will two foot baffles work on each side when drying the 12' 6" lumber? Will electric bill be the same with both charges? No sawmills are using dry kilns in this area. Can I expect to get business from them or their customers? If anyone has any feedback on the best size chamber to build that would be great.

Forum Responses
(Sawing and Drying Forum)
From Gene Wengert, forum technical advisor:
What is the hp of the compressor? This is the key. Nyle sells the plans for a kiln that have been tested and refined over the years. Purchase their plans, once we know the hp.

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From the original questioner:
The unit is the Nyle L200 and I have the plans. The chamber dimensions changes with different length lumber. I only run my sawmill business part time. First I was going to build a chamber to hold only 2000BF, now I'm thinking about building a chamber to hold 2500 or 3000 BF at 16' length for future growth.

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From contributor T:
I can't help you with the kiln plans, but glad you’re looking at future expansion. We all get into the budget pinching and sometimes forget our growth plan. I think you’re being wise to build an expanded size now than tear out and expand later.

Seems to be something with the extra/dead air space from my readings in the past but should override the crying of wish I built it bigger. Somebody here should be able to help you with the extra/empty space. An idea of maybe building moisture resistant foam/insulated filler boxes that would be light weight to move but sealed full of dead air that replaces air volume not needing drying?

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From Gene Wengert, forum technical advisor:
I assume you have and will have a lot of 16' logs. Certainly 12' is more common for many hardwoods and sometimes 8' is standard where pulpwood is big. Can your customers haul 16' lumber? Can you handle long lumber before and after drying? If not, then a 12' chamber might be better.

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From contributor F:
I have the WM DH4000 and I made the chamber 11' by 17'. I can put 8'6" boards end to end that way. I built it directly from the Nyle plans, cutting no corners. It is well insulated, $2000 in insulation alone. I wish I had put in a third fan, maybe in the future.

I sometimes get business from other mills, but don't expect to get rich with the kiln. I use customers’ wood as a means to pay the electric bill to dry my wood. I have started it up with as little as $200 of customers wood in it, I finish filling it with my own wood and let them pay for the electric. The last load was a load of oak that took 36 hours to get from 23 degrees up to 90 degrees. The bill for that load should be in the $200 range. I had 1136 bf of customers’ wood in it, paying me $340 with a profit of $140. However, I dried almost 2000 bf of my oak with it which is now sold for $4000.

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From contributor A:
I have a Nyle L200 and my kiln inside is 18' 6" long and 11' wide with a ten foot ceiling. My fans hang in a two foot drop from the ceiling and there is a carpet flap that drops to seal the top of the piles. The ends do not get sealed if they are short. I double stack a lot of 8' material in there. It will dry just fine and I do lots of pine and oak. I cannot tell what it uses in electric as it is on the same meter as the office and the planer shed with the Logosol. My slab has two inches of foam under it and the walls are six inches thick. The next chamber I build will be of ICF blocks by Nudura and the slab floor will be insulated from the footing.

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From contributor O:
I have a Nyle L200 setup in a refer container; two carts, one 20' and one 16'. I can get a little over 4000' if the lengths are right. Build the kiln bigger rather than smaller, especially if you're going to dry hardwoods. Used refrigerated containers run about $2500 - $3000, and most are all stainless and aluminum inside. They are extremely tight, have great doors, and need no other insulation. They are also very easy to move if that ever comes up (I've moved mine twice). If there aren't kilns in your area, I think you'll pick up some business for sure. I dry lumber for several other small mills.