IBC tote solar kiln

[Wisco Shepherd]

All right guys just got done constructing my kiln and wanted to give a little breakdown of how things are looking at the start. Big thanks to @Woodsplitter67 for a bit of guidance on the build.

So I first started out making a angled frame to hold the top plastic. I decided to do this as opposed to mounting up wood because I wanted to ensure that as the wood settled it wouldn't create any puddling and wanted to get myself the best chance of success. Frame is very basic I'm lucky enough to have a second hand lumber store near me so each Kiln cost about four dollars in lumber.

when ordering the poly I made a mistake and did not get enough to cover all four sides and roof so I ended up covering the roof and two sides that get the most sun and plastic wrapping the other two sides.

Venting was achieved at each side of the kiln and is adjustable based on temperatures.

Here's the finished product when all said and done.

I took two separate temperature readings today with an ambient temperature of 69°, the top of the Kiln was measuring around 125° to 130° and about halfway down was measuring right around 105. Most of the wood in this Kiln is Oak in two totes and Maple in one so I'm planning on leaving it for at least 60 days potentially 70-90 for the oak as it was pretty wet when I cut it in May and only had two months to dry out prior to the kiln. I will update in this thread my results.

 

[EatenByLimestone]

Excellent idea! Out of curiosity, do you think you’ll pull much moisture from the soil? I wonder if setting it on another pallet to lift it a few inches higher up would help drying.


I like the idea of not having to touch it until you’re ready to burn!

 

[Wisco Shepherd]

Excellent idea! Out of curiosity, do you think you’ll pull much moisture from the soil? I wonder if setting it on another pallet to lift it a few inches higher up would help drying.


I like the idea of not having to touch it until you’re ready to burn!

It may pull a tiny bit but the bottom of these totes is solid metal no venting other than a small opening towards the front where the spigot comes out. Elevating off the ground would have been a good idea but totes were full before I built the kilns.

 

[EatenByLimestone]

Oh, with the solid bottom it shouldn’t be an issue!

 

[peakbagger]

Looks slick to me. I might try to locate the vent hole to the highest spot possible but I expect once you get past the initial couple of weeks drivign off the surface water, that it will not make a difference. If there is not enough air flow, its not that hard to cut a few holes down low along the sides, preferably on the shady side.

 

[Wisco Shepherd]

Looks slick to me. I might try to locate the vent hole to the highest spot possible but I expect once you get past the initial couple of weeks drivign off the surface water, that it will not make a difference. If there is not enough air flow, its not that hard to cut a few holes down low along the sides, preferably on the shady side.

Yeah I'll be checking early and often its a breezy spot up on a hill and I've got holes on both sides.

 

[Wisco Shepherd]

Grabbed a reasonably large chunk from the top a few days ago. Starting point was nearly 40 and I am down to 31 now 1 month in. Temps still in the 120 range when fully cranking and the array of totes faces south. I am thinking of adding some venting low on the kilns to get more air in but I may just stay the course. We have not had a lot of warm temps and this oak was sopping wet when it went in so it may not fully get there.

 

[Wisco Shepherd]

60 days in, took some measurements very happy with the progress on the elm which measured out around 16% and box elder fell all the way to 9% so that tote is getting unwrapped. The oak tote is still around 29%.

 

[bigealta]

This guys tote solar kiln do Not work. Wonder what the difference is?
He tested it against an uncovered tote.
Well it was just a 1 month test so maybe not enough time?
Actually maybe it did work, he got a 5% difference in 1 month. That seems ok to me?

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[bigealta]

I like how these guys do their totes.

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[Wisco Shepherd]

This guys tote solar kiln do Not work. Wonder what the difference is?
He tested it against an uncovered tote.
Well it was just a 1 month test so maybe not enough time?
Actually maybe it did work, he got a 5% difference in 1 month. That seems ok to me?

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Lots of variables, next time (if there is a next time now that I am getting ahead) I would elevate the totes off the ground some, increase intake venting from the lower part of the kiln, and spread them out further for more sun. But all in all they were a very small investment and seemed to help.

 

[bigealta]

i'm definitely keeping a close eye on these and other solar kilns as i'll have a gap year next season if i don't come up with a couple cords of fast drying wood pretty soon. after that i've got 4 cords of dead standing oak c/s/s last month. So should be good for after next season.

 

[Wisco Shepherd]

Tested a few more pieces today seems like almost everything in the top 1/3 of the totes is nice and dry around 15% but the lower stuff is still pretty wet with some pieces in the 30s Makes sense as most of the heat hangs out there. Maybe increased Venting down low or raising the totes off the ground.

I'll take what's dry this year and leave the rest for next year.

 

[Woodsplitter67]

Good job, thanks for posting your results and idea

 

[Woody Stover]

Tested a few more pieces today seems like almost everything in the top 1/3 of the totes is nice and dry around 15% but the lower stuff is still pretty wet with some pieces in the 30s Makes sense as most of the heat hangs out there. Maybe increased Venting down low or raising the totes off the ground.

But does more venting drop the temp inside? I haven't followed the kiln threads closely, but that question has probably been answered in some of them, and a lot of experimentation with the variables has probably been done.

 

[Wisco Shepherd]

But does more venting drop the temp inside? I haven't followed the kiln threads closely, but that question has probably been answered in some of them, and a lot of experimentation with the variables has probably been done.

It does, but some venting down low is needed to create the natural convection. My lower venting was quite small. My gut tells me that its just hard to get the lower half warm with this design.

 

[Woodsplitter67]

It does, but some venting down low is needed to create the natural convection. My lower venting was quite small. My gut tells me that its just hard to get the lower half warm with this design.

Your vents were a little on the larger side. Iv literally gotten my kiln up to 140 degrees. Smaller vents build up more heat. The hotter the air the more moisture you will strip from the wood. The hotter the top, enables you to build more heat at the bottom. Keeping the kiln up off the ground helps the process.

its not about how much air you can vent. The name of the game is to get the air as hot as possible because the hotter the air the drier it gets and will pull the moisture out. Lets just say for example its 90 degrees out and its 70% dewpoint. The same air in your kiln won't be 70%when its heated up to 140 degrees that air will be more like 10% dewpoint... robbing your wood of all its moisture..

Smaller vents and hotter kilns actually dry the wood faster

 

[Wisco Shepherd]

Your vents were a little on the larger side. Iv literally gotten my kiln up to 140 degrees. Smaller vents build up more heat. The hotter the air the more moisture you will strip from the wood. The hotter the top, enables you to build more heat at the bottom. Keeping the kiln up off the ground helps the process.

its not about how much air you can vent. The name of the game is to get the air as hot as possible because the hotter the air the drier it gets and will pull the moisture out. Lets just say for example its 90 degrees out and its 70% dewpoint. The same air in your kiln won't be 70%when its heated up to 140 degrees that air will be more like 10% dewpoint... robbing your wood of all its moisture..

Smaller vents and hotter kilns actually dry the wood faster

I did notice this and closed my vents down after letting some of the initial surface moisture out. Saw temps consistently in the 130s (I have a temp tracker that lived in there all summer) at the top of the kiln. I just don't think I had those same temps down low and the MC in my test splits seems to support that.