# Solar Kiln



## Norm192 (Jan 22, 2014)

Anyone have some insight on fanless solar kilns? I have seen some stuff online , via VA TECH I think. I have some reclaimed sliding glass doors, 3 doors= lots of glass. Problem is I don't have power where I want to put the kiln. Any experience going fan free? Tree?

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## Mike1950 (Jan 22, 2014)

Get a little solar fan off of ebay to suck the moist air out when the sun shines. we use one in the greenhouse.

Reactions: Agree 1


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## Norm192 (Jan 22, 2014)

$$ and do they hold up? I've heard some of that solar kiln stuff was set it and forget it.


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## Mike1950 (Jan 22, 2014)

I think the one we have cost less then $50 and it has worked for 3 years. Does not move a lot of air but you would not want to.

Reactions: Agree 1


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## Norm192 (Jan 22, 2014)

I was brainstorming with a friend about using a conex box ( shipping container ). I've opened some of them up and they had to be hot enough to dry wood and kill a bug. Pretty cheap and a lot of storage. Just ugly


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## Treecycle Hardwoods (Jan 22, 2014)

Ok here is my .02...... to dry wood you need air flow or you won't be drying much and you would be creating an environment where mold could grow on your wood.

Like Mike said solar powered fans are the way to go. You need to match the solar panel output to the amount of power the fan will need. I am quite clumsy with electricity so I will save myself the embarrassment and skip the techno jargen on the electrical part.

There are hundreds of blogs, articles, and information sites about solar kilns on the web. Sorting thru them can be daunting so first(which I think is already done) is decide much wood you want/need to dry each time you load it up and focus on the info out there for the size.

You had mentioned a container and how hot it gets. What is bad about a container is it has very poor insulation. If you insulate it you remove that good quality you are after. If you insulate in inside you prevent heat radiation. If you insulate the outside you block the sun and it won't heat up. 

The solar kiln setup I am gonna use is the Appalachian trail kiln. I tried linking it but can't figure it out on my phone. For the most efficient solar kiln you need it to face south and have a glass/radiation pannel equal or greater than your latitude. So for me in WI I need to be 45* or steeper to catch as much solar energy as possible. If I went 50 -55* it would increase efficiency in the winter and decrease it in the summer. 

The deal with solar kilns is you want to let the energy in and keep it there. Ordinary glass will work but there is special glass that can be purchased that is better at this. The plans I referenced above outlines a ratio of glass surface area to chamber size so you maximize drying efficiency. Below the glass is a panel that collect and radiate energy. This is partially why containers seem good. They naturally heat up when exposed to the sun and radiate the heat inward. The radiation pannel also shields the wood from harmful UV rays. The info I pointed to earlier uses several layers of dark aluminum screen for this. 

You can get away with as little as a couple hundred bucks to build a solar kiln. Or go all out and spend 4 or 6 thousand. The better quality kiln you build the quicker turn around on drying time you will have. In some areas of the country summer is short so efficiency is key to maximize the summer sun! Another good thing to keep in mind is how well sealed your kiln is. Letting air escape will reduce your control over the process. In the beginning you want to keep the humidity high in the kiln. Having a poor or uncontrolled seal you may dry to quickly in the beginning and end up with surface checking. I can't emphasize enough that air flow is VERY important without it drying won't go very smoothly for you. Let me know if you can't find the info I referenced I could maybe scan and email my printed copy to you.

I basically regurgitated the info from the Appalachian trail article in reduced form. I would recommend reading thru it along with a few other sources that line up with your ideal size and climate.

If you need any more help just drop me a line.


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## Tclem (Jan 22, 2014)

What about have duct work from one side to the other with a fan blowing into one end which would circulate the hot air back into the other side


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## Mike1950 (Jan 22, 2014)

I would use the fan to blow air out and at the other end on the bottom have a vent to pull air in. The ideal is you move the warm moist air out and the dry air in. My uninsulated greenhouse with the door shut and window shut would get to 130 plus in the summer -easy. It is a reused costco tent frame with clear plastic on it - I have suggested using as a kiln but the little woman had her own suggestions which I shall not repeat. Be careful or your kiln will be way too hot.........


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## Treecycle Hardwoods (Jan 22, 2014)

Tclem said:


> What about have duct work from one side to the other with a fan blowing into one end which would circulate the hot air back into the other side


Some how you need to let the moisture out of the system or no drying will happen. The best way to do this is with vents that you adjust at the top and bottom on the north side of the kiln. The vents are closed or nearly closed to start the load then as time goes on you open them more.


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## Norm192 (Jan 23, 2014)

Thanks all. Probably be summertime before I get around to building one. What you said Greg agrees with most of what I've read about traditional solar kilns. I'm just weighing all the options.
I didn't think about the tent frame Mike, but if I make anything resembling a greenhouse my wife will definitely claim it!

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## Treecycle Hardwoods (Jan 23, 2014)

@Tclem here is the link to the solar kiln i had referenced above. There is other plans there as well but the specifice one above is the Third one down the list.
http://www.builditsolar.com/Projects/WoodDrying/wood_kiln.htm

I have built the 3 dehumidification kilns I am currently using each being able to hold 1200, 1000, and 300 BF respectively. The construction of a solar kiln and dehumidification kiln are pretty similar in the detail needed to seal them and insulate them. I feel that the Appalachian State University plan is the best in terms of describing the whole process and building materials for the solar kiln and many aspects overlap the dehumidification kiln. Hopefully this helps anyone who is looking to build one of these kilns.

I am here to help if anybody needs it. Good luck Gents!

Reactions: Informative 2


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## Graybeard (Jan 25, 2014)

Check out Glen Lucas video on how he uses old refrigerated truck boxes to dry down wood. He's got a lot invested in it, but then he's got a lot invested in his wood too.

Graybeard


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