Pseudo-kiln. does this make sense?

[flashhole]

I run a dehumidifer in my basement. The water drip has a hose fitting and I have it run to a drain. I never have to empty a catch pan. The unit reads out ambient air temp and relative humidity. Like all dehumidifiers, it circulates room air over the condenser and blows heat out the back. It occurred to me having a dehumidifer in a confined area might be a good way to dry the milled lumber. It would continuously cycle the air in the enclosed space and be self heating. It wouldn't reach kiln temperatures but it should speed up the process. Maybe a light bulb or two for some extra heat? Does this make any sense?

 

[lps8]

dehumidifier

I don't know how long it would take, but this will work to a certain extent.

I don't know about how much it will bring the humidity down, but what I did was to dry my cedar in a drying oven I use at my business for drying plastic (you get bubbles in polycarbonate if there is moisture in it when you thermoform it), then I sealed a 20x40 room with poly in my house while I was building it and ran 2 dehumidifiers to keep the moisture down while I built my exterior doors and my cabinets. I would take the moisture down to below 7% in my drying oven, then put it in the house with the dehumidifiers during the install. I have syp floors and log cabin siding, and white pine for some walls and all the ceiling. I also dried it prior to installing because I wanted a tight joint in my 1x6 flooring and walls.

I found out years ago that lumber for the lumber yard that is stored outside will have a moisture content of 15-18% even after being kiln dried. Inside my house was 6/7% and after I put up some t&g poplar, it later shrank up quite a bit. So all my interior wood was dried and maintained below 7% before I put it up.

Hope this helps.

Larry

 

[marti384]

Dehumidifiers can be expensive to run continuously. The one in my basement adds $45 to my electric bill every month in the summer. Depending on how long you need to run it, it may be cheaper to build a solar kiln. Although it probably would work eventually.

 

[Dave Boyt]

Dehumidification kilns work on a similar principle to what you described. Measuring the amount of water put out by the dehumidifier gives the kiln operator a good idea of how much moisture has been pulled out of the boards. The better the insulation, the less energy you'll use, though I doubt you'll find light bulbs capable of putting out enough heat to do much good. Ideally, you want to maintain around 135 degrees F to kill any bugs. Household dehumidifiers aren't designed to handle the liquid pulled out of the boards and will corrode. You could get by with one for occasional use. Dehumidifiers designed for kilns (like Nyle) are built out of stainless steel. You'll need some fans to circulate the air. Finally, get yourself a good moisture meter so you can keep track of what the wood is doing.

Solar kiln gets my vote. Do a search for the Virginia Tech solar kiln. Good luck!

 

[BobL]

. . . . . You'll need some fans to circulate the air. Finally, get yourself a good moisture meter so you can keep track of what the wood is doing.

Solar kiln gets my vote. Do a search for the Virginia Tech solar kiln. Good luck!

It depends on how fast you want to dry your timber but most kiln designers designers usually significantly underestimate the amount of energy needed for internal recirculation. The sorts of figures I see recommended for kilns are 1 to 1.5 W of recirculation power per cubic fit of volume. If this is not done then other devices/system controlling temp and humidity don't work efficiently. This can all become quite expensive so your lumber needs to be valuable to warrant the energy costs. Of course you can choose to do things much slower and passive but you still need some recirc otherwise the differences between your dead and active spaces can stress the wood.