Solar kilns

[StihlHead]

Ah yes, deer hunting season is leaking into my brain ahead of ski patrol season. Sublimation... not evisceration.

Of course, maybe I suffer from the sublimation as used in psychology, where it is defined by a mature type of defense mechanism where socially unacceptable impulses or idealizations are consciously transformed into socially acceptable actions or behavior, possibly resulting in a long-term conversion of the initial impulse. Whatever that means...

I have found that ice covered firewood will dry below freezing here if I move it to a dry location. That is re-wetted firewood though, and not green. And it takes exposure to air to do it so it has to be stacked really loose.

 

[StihlHead]

Could even take this one step further, and build a DIY heliostat to keep the sunlight on the kiln for longer periods of time.

Snow works great for that here when it is on the ground. Building a solar concentrator (or wood cooker) would have to be rather large, and for many the issue is reducing space. It would also have to put up who a lot of wind here in the Cascades, as well as snow loading.

 

[Augie]

It is somewhat limited in scope, did not have a control group and provided no actual data, but is still very encouraging. Much more promising than the Alaska study. I would like to see someone take a batch of green oak (both split and small diameter unsplit rounds), divide it into 2 stacks side by side and construct a solar kiln over one. Then take moisture measurements over the course of a summer. Based on this white paper, I suspect it would be beneficial for people with limited storage space to build solar kilns.

So I did have some Oak out of the kiln from the same tree. It was still reading 35+ percent MC when the Kiln oak was dry. I didn't take measurements every month, because I am out doing other things besides watching my wood dry.

I know that it works now, so I don't feel like preforming another experiment to determine exactly how well it works. LOL

I put the wood in, and it comes out in 4 months ready to burn. I have posted my sources and described my process. This isn't academic research, I do know how to write a white paper, but I dont think I should need a control group to prove my results. The internet is pessimistic by nature, no matter how much proof I provide someone will say I faked it or it isn't true.

I put exactly as much effort into "testing" as I feel was necessary to determine if it worked for me.

I have let the forum know what works for me, and Ill post whenever someone brings it up, but I don't feel it necessary to prove to the internet in general what I have found works for me.

Take it for what you believe it is worth.

C/N:Homemade Solar Kilns work for drying Oak, in Michigan, in four months, I'm too crotchety to put more effort into proving how well it works.

 

[MrWhoopee]

So I did have some Oak out of the kiln from the same tree. It was still reading 35+ percent MC when the Kiln oak was dry. I didn't take measurements every month, because I am out doing other things besides watching my wood dry.

I know that it works now, so I don't feel like preforming another experiment to determine exactly how well it works. LOL

I put the wood in, and it comes out in 4 months ready to burn. I have posted my sources and described my process. This isn't academic research, I do know how to write a white paper, but I dont think I should need a control group to prove my results. The internet is pessimistic by nature, no matter how much proof I provide someone will say I faked it or it isn't true.
I put exactly as much effort into "testing" as I feel was necessary to determine if it worked for me.

I have let the forum know what works for me, and Ill post whenever someone brings it up, but I don't feel it necessary to prove to the internet in general what I have found works for me.

Take it for what you believe it is worth.

C/N:Homemade Solar Kilns work for drying Oak, in Michigan, in four months, I'm too crotchety to put more effort into proving how well it works.

So you did have a control group. That's good enough for me. It's the final result that counts, anything in between is just to confirm the trend and validate the final result.

 

[StihlHead]

Take it for what you believe it is worth.

Yes, we are saturated with double blind studies and endless debates about what exactly is inside of a ping pong ball (or as in this case, a passive solar wood kiln). And whatever the results, they will be refuted by some non-believers or religious faction that does not believe in some particular scientific finding or phenomena, no matter how high the mountain of proof (I submit evolution as but one example). Then it has to be ground up and regulated by some authoritative government entity and looked over for any potential for taxation, licensing, further legislation, or outlawing if it is too controversial or conflicts with a majority (or in some cases, a minority) opinion, or impedes on some business monopoly or registered patents. If it is then challenged, it will spend an eternity in the court system to be dissected and analyzed, and some eventual ruling will result that will likely start the entire process all over again.

Go split your rounds... or better yet, put your chainsaw in a new movie as we are simply dying of boredom out here in the real world.

 

[NortheastAl]

Augie, I'm sure you don't want to redo something you are quite sure works well. I have confidence in your use of the kiln, and that it worked. I also happen to trust Cornell, seeing they are in NY, and must have done the test in NY. Going to give it a try in the spring because of the need for space. Adding almost 4 more cord of wood is going to be a problem. Too many steep places on the property, and I don't want to waste what precious little flatland we have.

Thanks for keeping this in the forefront. For those of us with smaller lots this may be the only answer to having truly dry firewood.

 

[Augie]

So I am guessing that if I tent up a cord or two this fall once the leaves drop I will have enough sunlight to heat and season a cord by the time the leaves begin to grow next spring, Likely 6 months away, we shall see

 

[PapaDave]

 

[jebatty]

Solar kilns, any device in fact, that provides heat and air movement will dry wood at least to the equilibrium moisture level of the surrounding air. All involve time, and the thicker the splits, the longer it will take. And most involve energy input with fans, heaters, dehumidifiers, etc., which are costly.

I have a simple solar dry kiln which I built to dry lumber, mostly pine but also some birch, oak and ash. All of my lumber was 1 - 2" rough cut. It's not easy to achieve even drying through the board, and I would think it would be much harder to obtain even drying through a firewood split. There needs to be lots of air space between the boards or splits to carry away the moisture. A 2" x ___ might end up with 6% MC near the ends and pockets of +30% at different points in the board. For lumber purposes it worked best to sticker and air dry in a covered space with air circulation after the kiln drying to achieve an evenly dried board suitable for finish lumber purposes.

During a hot, windy and dry period during the summer stickered kiln lumber dried no faster than stickered air dried, and the stickered air dried was more evenly dry. But in a wet, cool, and calm environment, the kiln out-performed the air drying. Both, with sufficient time, produced equivalent quality of drying.

Since I burn splits generally up to about 8" in thickness, and of course thinner splits, I really can't imagine trying to sticker and kiln dry splits of varying thickness. The thin splits will be more dry, the thick splits will be less dry. I think it can work and can speed drying, but for me the handling, cost of fans, cost of building and maintaining the kiln, etc., all are outweighed by air drying and letting nature do the work without the additional cost.

 

[Craig S.]

Could even take this one step further, and build a DIY heliostat to keep the sunlight on the kiln for longer periods of time.

Here's one ... watch the videos, for $299 it could certainly be used to concentrate sunlight on a woodpile, or woodshed.
(broken link removed to http://wikoda.com/the-sunflower/)

 

[Augie]

If you want to season oak in 3months try this. It has been working for me

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[bodhran]

If you want to season oak in 3months try this. It has been working for me

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How long do you think it would take to dry balsam fir and spruce?

 

[jaoneill]

One of my brothers built a fairly large (20'x40'x12'H) woodshed that also houses his outdoor boiler. It is sided and roofed with metal but a substantial part of it is clear polycarbonate. It has a foot or so of intake at the base of the perimeter and plenty of roof ventilation. Average daytime temps inside through the summer are well in excess of 100 degrees. His wood goes in green in April/May and is down to 15% by September.
I try to get my woodshed filled by early July with wood that has been partially seasoned (25% or so). Although I don't have the advantage of solar, I have an old 1/4 hp, slow speed furnace blower that uses a negligible amount of electricity but creates a constant strong breeze (of warm summer air) through the wood during the daylight hours. I resplit a few pieces of hard maple yesterday and found the moisture at 15%-18%, cherry was all below 15%. I generally put the blower away when the weather cools off in late September. Should be in good shape by heating season this year.

 

[Babaganoosh]

I'm not sure how that first report by the forestry place got that it peaked at 9 degrees hotter because I have wood in just shrink wrap and I've gotten temperature readings as high as 160.

 

[turn_n_burn]

I'm a firm believer in dark colored surfaces to absorb radiant heat. A black car gets hotter inside than a white one.