# Theory: Dehumidifier + green wood = good wood



## Zuki (Mar 28, 2007)

I was thinking. Could a dehumidifier be used to lower the moisture content in wood.

My theory:
- Built a small rectangular frame (large enough to put in a home dehumidifier)
- Cover the frame in plastic leaving a flap on each end to give access to the interior
- Put the dehumidifier in one end
- Stack the wood in through the other end 
- Lower the flaps
- Turn on the dehumidifier
- Wait

I'm guessing that this would be a more aggressive way of removing moisture, however if it ran for an hour or two every day for a week . . . one should be left with usable wood.

What do you think?


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## DanYo (Jun 30, 2007)

yep … it would work


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## Russel (Aug 13, 2007)

Interesting idea. I might be concerned about the wood drying evenly. Would the wood closest to the dehumidifier be drier than that furthest away?


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## Zuki (Mar 28, 2007)

Rotating, flipping and restacking the wood could also be incorporated into the equation.

Of course the wood would be stickered (?) . . . separated by small strips.


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## PaulfromVictor (Mar 29, 2009)

I think that just a little warmth and good air circulation would work better than making the air drier. I have never actually dried wood, but I have worked with plenty of air dried wood. People that are good at it have it down to a science. I don't recall ever reading about a dehumidifier being included as part of the equation.


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## Timbo (Aug 21, 2008)

You probably want to investigate to what humidity level the dehumidifier cycles, it may not be low enough.


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## Zuki (Mar 28, 2007)

Good point Tim. Our lowest setting was 45%, however there is an override that will allow it to run much lower.


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## Rasta (Dec 22, 2008)

I read an article about a home built kiln like this possibly Wood magazine? Try theirr website.


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## bsherman (Sep 28, 2008)

Are dehumidifiers expensive to run? (Like air conditioners?) If so I wonder how cost effective that would be


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## GFYS (Nov 23, 2008)

Not only would work…does work. Daren has a plan for a small dehumidifying kiln on the Woodworkers Forum
http://www.woodworkingtalk.com/f23/small-wood-drying-kiln-plans-dry-your-own-lumber-3103/index2/
He is also a member of LJ


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## alby (Dec 31, 2009)

zuki

Yes a dehumidifier does work but you have to be carefull.

- The ends of the wood should be sealed with a oil base paint or something that prevents moisture from excaping.
- You should have the wood stickered, and it should be waited down.
- You have to keep air, fan 24/7, on it so the wood will dry at an even rate. 
- If the moisture is drawn off too quickly, you can "case harden" the wood. You won't know that until you shove it through a saw. Then it's too late.
- 45% air moisture will problablely bring the wood down to 8 - 10 %
- Try a small amount first.

Alby


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## bill1352 (Nov 8, 2009)

Not sure if Dan with the ebay link is the same guy but there is an ad on ebay for plans to build a home kiln. $25. gives a phone number to talk to the guy if you buy the plans.


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## snowdog (Jul 1, 2007)

I have not had a lot of luck drying wood so far but I have not really did a deep dive on the science of drying wood. But what I have seen is that slow is good fast is bad <laugh> not a lot of new news there . 
One of my first errors was using a latex paint to seal the ends, yes that did not work. Oil paint keeps the wood sealed so it drys slower (less checking and splits)


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## Julian (Sep 30, 2008)

Dan's link is not to ebay, it's to another forum that talks about the plans for sale by Daren. They are great plans and Daren is a real stand up guy.


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## snowdog (Jul 1, 2007)

I have not had a lot of luck drying wood so far but I have not really did a deep dive on the science of drying wood. But what I have seen is that slow is good fast is bad <laugh> not a lot of new news there . 
One of my first errors was using a latex paint to seal the ends, yes that did not work. Oil paint keeps the wood sealed so it drys slower (less checking and splits)


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## Daren (Sep 16, 2007)

Zuki your theory is sound and so far the advice you have been given here is good. I will throw this link out to maybe help you, it's a calculator for EMC (equilibrium moisture content) of wood at a given air temperature and rh (relative humidity) http://www.csgnetwork.com/emctablecalc.html Like you said you will want to go lower than 45% on your unit. Good luck.


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## dustmaker (Dec 17, 2008)

I have made and use a dehumidifier kiln. I have used it twice and it took about 6 weeks to go from 13% to 7% moisture. I haven't tried green wood in it yet. I have been taking air dried and drying even more. I have a heat source of a 500 watt halogen light and a fan that circulates the air continuiously. It does work but the caution that a home dehumidfier will be affected by the acids from walnut and oak. My dehumidifier is a marine dehumidifier. Research the web from different sights then go for it.


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## rusticandy (Sep 26, 2008)

go to the woodweb and there arel ots of posts- they generally discourage using home dehumidifers as they are underpowered and they burn out. A solar kiln is much more effective if you are trying to go on the cheap.


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## Zuki (Mar 28, 2007)

Ok. Consensus is that the theory checks out.

I'll go check out those sites and do a bit of reading.

I'm looking at doing some construction grade spruce. 2×12s

And of course I will blog it here.

Thanks folks.


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