Solar kiln....

[Tar12]

Poindexters and Woodsplitter67s results can not be denied...it works! I am about to embark upon building my own...I have enough room down the side of my drive to do 5 cord at a time...this area receives full sun all day...I would prefer to build something permanent minus the plastic...my goal is dry large splits of White Oak for those bitter winter nights...I need some input and ideas...I work for a concrete company so I can pour a pad for free

 

[Woodsplitter67]

Its a football sunday for me.. i will reply back later tonight or tomorrow...

 

[Woodsplitter67]

So.. here is my thought on this, and i am also doing this myself
I took a small amount of wood and did a test. My test wood was just inder a cord. I gave my self 1 summer to see how it goes and also how i could improve on what i was doing and also if i make a mistake its not with multiple cords.
Now i have enough experience to make some changes and improve my design and also change how i am splitting the wood as well as species of wood will go into the kiln. Five cords is alot.. i would start with 1 ....2 at the most. Also you could do more then 1 kiln run per season. I figured out that i could actually get 3 cords dry and only doing 1.5 cords at a time probably more if i wanted.

So do a little experiment see how it goes learn alot and apply it to the following year or the next kiln run

 

[Poindexter]

I m thinking about using clear corrugated roofing panels on the from the head knocker beam on the shady side up over the top and down to the floor on the sunny side. Then I can just rig shower curtains to the head knocker beam on the shady side to open and close the kiln.

I am a little bit concerned about wind, and I haven't seen clear corrugated without UV blocker in it at my local Lowes-Depot yet.

I would counsel waiting to see pics of woodsplitter67's flooring system before you pour, it sounds like he maybe pushed the envelope a little bit further than I had at first appreciated.

 

[Woodsplitter67]

Here is a pic of the wood rack i used. I wound up with more wood than could fit in the wood shed. I got the racks from home depot. They have a 2x4 bottom. I raised them up with pavers to get air under the entire rack

 

[Tar12]

I was looking at the Tuftex panels....89% light transmission with a temp range of -40-270 degree..it does have UV blocker....is it absolutely imperative that the panels not have UV blocker? If so what are the alternatives?

 

[Poindexter]

I dont know if its imperative. Physics was one of very few classes in high school where i earned an A.

UV radiation passes through clear panels like glass or clear plastic unchanged, but becomes heat when it smacks into an opaque object - like the wood inside the kiln. That heat can then be trapped by the clear panels...

Compare to visible light that passes through clear panels like glass unchanged, and then part of the color spectrum is absorbed by an opaque object and the remainder comes back out through the glass again - so you can see what color couch your neighbor has from the sidewalk.

In theory UV blockers in the membrane will limit the peak temps you can get in your kiln, your wood will take "longer" to dry, but i dont know how much longer.

In practice it might not make a measurable difference, i dont know anyone who has tried it for cord wood drying.

 

[redktmrider]

I was looking at the Tuftex panels....89% light transmission with a temp range of -40-270 degree..it does have UV blocker....is it absolutely imperative that the panels not have UV blocker? If so what are the alternatives?

I use the Tuftex panels in my kiln. I can dry white oak from 30% down to about 15% moisture in 5-6 months.

My setup is like a traditional lumber drying kiln and was a bit expensive to build, as it is sided with traditional yard barn siding, painted, etc, but my wife is sensitive to how things look in our neighborhood so I had to make it look somewhat nice.
I will get some pictures of my kiln tomorrow and post them here.

 

[Poindexter]

I wonder if that stuff @Woodsplitter67 used as a membrane has UV blockers in it? His got plenty hot in there.

I am using the cheap plastic 6mil rolls of clear from Home Depot and routinely see 140s dF in there on bright sunny summer days.

 

[Poindexter]

You know, sheet metal roofing on roof and walls might be worth a try. I remember having to use an outhouse sheathed in that stuff once. Not quite big enough to hold a full cord, but it was memorably hot in there.

 

[Tar12]

I use the Tuftex panels in my kiln. I can dry white oak from 30% down to about 15% moisture in 5-6 months.

My setup is like a traditional lumber drying kiln and was a bit expensive to build, as it is sided with traditional yard barn siding, painted, etc, but my wife is sensitive to how things look in our neighborhood so I had to make it look somewhat nice.
I will get some pictures of my kiln tomorrow and post them here.

Please do!

 

[Tar12]

You know, sheet metal roofing on roof and walls might be worth a try. I remember having to use an outhouse sheathed in that stuff once. Not quite big enough to hold a full cord, but it was memorably hot in there.

Lol...the poly port-a-jons get pretty warm..I can only imagine what the metal out house would be like!

 

[redktmrider]

So here is my kiln.
The dimensions are 15 ft long. 42 inches deep, short wall is 63 inches tall, long wall 102 inches. The whole kiln, except for the trim, is constructed of pressure treated lumber.
The base is 2x6 construction with vapor barrier and r13 insulation under 1/2 inch plywood, walls are 2x4 with r13 covered inside with tar paper.
The panels are clear Tuftex polycarbonate panels that I bought at Lowes.

The small white boards at the base of the side tuftex panels are removable, so I vent the kiln by removing the boards and opening the upper doors on the opposite side.


The kiln roughly holds 1/2 cord. Inside are three cheap box fans that I run with a small generator.
With the Tuftex panels, I see internal temps about 25 to 30F higher than the ambient temp on a sunny day.

So far I have dried 1/2 cord of white oak, with the second 1/2 cord of the same in the kiln right now.
The first cord went in at about 30% water came out at 15% about 5 months later.
I tried the kiln without the fans for the first three months, but the drying was not consistent throughout the stack, so I added the fans, which made drying much more even.

 

[w00zy]

Thoughts on modifying a greenhouse kit from harbor freight?

https://www.harborfreight.com/10-ft-x-12-ft-greenhouse-with-4-vents-63353.html

I can't build a shed that size for anywhere close to that price, although any shed I built would probably be 10x as strong.

 

[Poindexter]

@w00zy , i agree the price is hard to beat.

Snow load capacity will be a problem for some.

The other thing is the floor. Woodsplitter67 got away with an open floor on his property - and i am happy for him.

I am on a flood plain, my water table is only a few feet down. I found pallets was betyer than stacking green wood on the grass. Cinder blocks under the pallets was even better, but i got my best results with cinder blocks, the pallets, then a layer of plastic to keep the ground water out, then green splits and finally top covered.

What is going to work for you is going to depend partly on your local conditions.

 

[redktmrider]

Thoughts on modifying a greenhouse kit from harbor freight?

You will need some way to move air thru the greenhouse, I seen guys on the net with similar setups use a fan at one end to pull air through it.

 

[skw]

You know, sheet metal roofing on roof and walls might be worth a try. I remember having to use an outhouse sheathed in that stuff once. Not quite big enough to hold a full cord, but it was memorably hot in there.

My father in law had a large loft in his garage in the midwest. It was a sheet metal clad pole building. He used the loft for drying lumber. It got nice and toasty in the summer, and the wood dried out. Based on that experience, a sheet metal building seems like it would work for drying firewood as well. I am not sure how well it would work *compared* to a building with a transparent panel.

If I were trying it, I would go with black (or the darkest color possible) on the roof for maximum solar gain.

 

[skw]

Here is a pic of the wood rack i used. I wound up with more wood than could fit in the wood shed. I got the racks from home depot. They have a 2x4 bottom. I raised them up with pavers to get air under the entire rackView attachment 217085

Did anyone else notice that the firewood in this picture of the wood rack is "photoshopped" in? Filling a whole rack with wood for the picture was too much work I suppose! LOL

 

[BrotherBart]

Did anyone else notice that the firewood in this picture of the wood rack is "photoshopped" in? Filling a whole rack with wood for the picture was too much work I suppose! LOL

I wish Photoshop could fill the seven of those racks that I have.

 

[Woodsplitter67]

So here is my kiln.
The dimensions are 15 ft long. 42 inches deep, short wall is 63 inches tall, long wall 102 inches. The whole kiln, except for the trim, is constructed of pressure treated lumber.
The base is 2x6 construction with vapor barrier and r13 insulation under 1/2 inch plywood, walls are 2x4 with r13 covered inside with tar paper.
The panels are clear Tuftex polycarbonate panels that I bought at Lowes.

The small white boards at the base of the side tuftex panels are removable, so I vent the kiln by removing the boards and opening the upper doors on the opposite side.
View attachment 217141 View attachment 217142

The kiln roughly holds 1/2 cord. Inside are three cheap box fans that I run with a small generator.
With the Tuftex panels, I see internal temps about 25 to 30F higher than the ambient temp on a sunny day.

So far I have dried 1/2 cord of white oak, with the second 1/2 cord of the same in the kiln right now.
The first cord went in at about 30% water came out at 15% about 5 months later.
I tried the kiln without the fans for the first three months, but the drying was not consistent throughout the stack, so I added the fans, which made drying much more even.

Looking at your kiln it truly inspiring. What a nice build.
This year my plan was to take my mig welder and weld my own custome racks and increase my drying capacity.
I may be now looking at incorporating the racks into a more permanent design.
Something to walk in holding multiple cords

 

[redktmrider]

This year my plan was to take my mig welder and weld my own custome racks and increase my drying capacity.
I may be now looking at incorporating the racks into a more permanent design.
Something to walk in holding multiple cords

I had a similar thought on wood racks myself, but haven't made any headway on it yet . I would like to make some that are a true 48 inches tall from the base as most commercial racks are much shorter.
My only concern about making the racks is paint. It would be nice to have them powder coated, but I have no idea on the cost of that. My spray paint jobs usually don't do well outside.
There is a local guy that makes firewood racks out of stainless, but I haven't priced them.

 

[Woodsplitter67]

I had a similar thought on wood racks myself, but haven't made any headway on it yet . I would like to make some that are a true 48 inches tall from the base as most commercial racks are much shorter.
My only concern about making the racks is paint. It would be nice to have them powder coated, but I have no idea on the cost of that. My spray paint jobs usually don't do well outside.
There is a local guy that makes firewood racks out of stainless, but I haven't priced them.

After fabrication i am using a good primer. Depending on the color i am mostly using a high quality tractor enamel. Getting it fron tractor supply or another store that sells it. Doing 3 coats and i dont thin it to much.i have gotten good results with it. I am using a gravity feed cup air paint gun with an air regular that plugs in to the supply line and air hose for the best air control.