Late Season / Winter Solar Kilns

[Woodsplitter67]

i built my son a greenhouse this past September.. its not heated during the day and the temps in there show that you can dry the wood in a kiln over the winter. your observation is right that the heating inside is shorter than in the summer. i beleave that doing a kiln in winter will work and dry wood but just not as fast as in the spring, summer,early fall. the otherday it was in the upper 30s outside with a 15 to 20mph wind inside the greenhouse it was 82 and the RH was 5%

 

[Woodsplitter67]

also i dont pre season my wood.. my wood that goes in the kiln is still green. i let it sit for 3 months prior to doing the kiln. this will let out an abundance of moisture from the wood. doing this will keep alot of condensation out of the kiln and aid in seasoning. when i do the kiln my wood is still in the 30s ... just not the upper 30s..

 

[Coalescent]

also i dont pre season my wood.. my wood that goes in the kiln is still green. i let it sit for 3 months prior to doing the kiln. this will let out an abundance of moisture from the wood. doing this will keep alot of condensation out of the kiln and aid in seasoning. when i do the kiln my wood is still in the 30s ... just not the upper 30s..

Hello @Jan Pijpelink and @Woodsplitter67 ,

I am sorry I misrepresented you guys in my last post. Serves me right for trying to multitask and write a post at the same time as trying to attend to something else that needed doing.

My goal was to convey that I put my wood into the kilns wet and green, more so than what I understood you to have done. I didn't mean to suggest that you had truly seasoned your wood first, only that you'd left it out for a while.

I also want to make it clear to anyone else reading this thread that I think leaving the wood out for a bit is a better idea. I did what I did only because I was out of time and was determined to avoid buying firewood from someone else.

My family and I benefited enormously from the projects you've shared with this community... I have almost 5 cords of sub-20% wood to burn thanks to your shared designs! My purpose with this thread was to share my experience and provide a little more data and one more voice saying "Hey, I tried this too, and it really works... even in wet, cold central NH in the Fall!"

I wanted to strike-through my previous post and add these comments there, but I seem to have lost my ability to edit my posts.

 

[SpaceBus]

That's awesome, I wouldn't have thought it possible. I'd like to build a permanent kiln with some leftover windows and sliding door panels if even just to kill all the bugs.

 

[Jan Pijpelink]

Hello @Jan Pijpelink and @Woodsplitter67 ,

I am sorry I misrepresented you guys in my last post. Serves me right for trying to multitask and write a post at the same time as trying to attend to something else that needed doing.

My goal was to convey that I put my wood into the kilns wet and green, more so than what I understood you to have done. I didn't mean to suggest that you had truly seasoned your wood first, only that you'd left it out for a while.

I also want to make it clear to anyone else reading this thread that I think leaving the wood out for a bit is a better idea. I did what I did only because I was out of time and was determined to avoid buying firewood from someone else.

My family and I benefited enormously from the projects you've shared with this community... I have almost 5 cords of sub-20% wood to burn thanks to your shared designs! My purpose with this thread was to share my experience and provide a little more data and one more voice saying "Hey, I tried this too, and it really works... even in wet, cold central NH in the Fall!"

I wanted to strike-through my previous post and add these comments there, but I seem to have lost my ability to edit my posts.

Thanks. I got my tricks from @Woodsplitter67 and @Poindexter. They taught me a lot. Anyway, what works for me is this:
1- Cut, split and stack wood in the first 3 months of the year.
2- Let it expose to sun and wind for 3+ months.
3- Then wrap the kiln around the stack with a few breathing holes at the top of the kiln.
4- Leave it there till Oct/Nov.
5- It will be below 15%.

Note: All depends on location, position to sun and wind, and local weather conditions.

 

[Poindexter]

What I do with mine is keep the internal kiln temperature under +95dF until the water is out all of the sap tubules. That bit of moisture can be done in two weeks or so of dry weather - the water molecules can wick themselves to the ends of the splits via capillary action just running up and down the tubules that are vertical in the standing tree trunk. Maybe longer for really knotty stuff or burls down by the stump end of the donor log, but pretty much two weeks.

Once the free water is out of tubules all that is left is the bound water inside the individual cells, mostly bound up in the cellulose we want to burn later. This is your fiber saturation point. Water out of the sap tubes, but otherwise green wet wood. Typically your meter will show you right about 30% MC give or take for most species, IIRC 28-32% MC covers 85% of wood species' FSP or fiber saturation point.

Without a meter, if your stack is still standing tall and not shifting around, you are still above FSP. Once your split starts drying below FSP, that is the tubes are empty and you are getting bound water out from inside individual cells, that is when your stacks start moving around because now with water coming out of the cells, the cells will change size and shape so the split will start changing size and shape.

Locally I just make sure i have everything stacked by Saint Patricks Day, March 17th. I just load em up and close them up. Consistently for me my stacks are well below FSP before the weather is hot enough to get my kilns hot enough to worry.

The concern for me is if the kiln gets too hot while there is still water in the sap tubules the ends of the tubes might shrink closed and trap water in there. I came up with 95dF from a scientific article about drying lumber that I linked to in my second kiln thread.

The edit button goes away a few hours after a post is first posted. I dunno how many hours.

 

[Woodsplitter67]

Hello @Jan Pijpelink and @Woodsplitter67 ,

I am sorry I misrepresented you guys in my last post. Serves me right for trying to multitask and write a post at the same time as trying to attend to something else that needed doing.

My goal was to convey that I put my wood into the kilns wet and green, more so than what I understood you to have done. I didn't mean to suggest that you had truly seasoned your wood first, only that you'd left it out for a while.

I also want to make it clear to anyone else reading this thread that I think leaving the wood out for a bit is a better idea. I did what I did only because I was out of time and was determined to avoid buying firewood from someone else.

My family and I benefited enormously from the projects you've shared with this community... I have almost 5 cords of sub-20% wood to burn thanks to your shared designs! My purpose with this thread was to share my experience and provide a little more data and one more voice saying "Hey, I tried this too, and it really works... even in wet, cold central NH in the Fall!"

I wanted to strike-through my previous post and add these comments there, but I seem to have lost my ability to edit my posts.

i want you to know that i am not upset in any way.. thank you for the correction. o just wanted to make sure that people know that my wood is still pretty green when i do the kiln.. its just not freshly cut and put in the kiln. im happy that this is working out for youand your sitting on 5 cords ready to bur with such a late start.. there have been many posts so fart of my woods wet.. now what..

 

[jaoneill]

Update on my experience this fall. Wood was blocked up in March/April, split, stacked on pallets and wrapped in groups of 4. Four groups with 1/2 cord on each pallet, 8 cord total, in full sun dawn til dusk. Moisture was averaging mid-twenties when split. First group was split and wrapped in early August, uncovered and put in the shed mid October at 12%-15%. Last group had only been wrapped for about 5 weeks when we also had 65mph winds that completely shredded all of the plastic. All were below 20% but the the final group, and they were down in the 20% neighborhood So I called it a day and moved all but a few pallets into the shed last weekend, and top covered those few until I have more room inside. To my way of thinking it was, all in all, a resounding success!

 

[Chas0218]

Anyone dabble with the clear poly carbonate panels? I would imagine it would have the same effect. I was thinking of building a solar kiln to dry rough sawn boards. The solar kilns I have seen are all painted black interiors with clear panels on the southern exposure side. Wouldn't this same concept work but for firewood? I'm just kind of thinking out loud but wouldn't mind input from you guys. I mean nothing venture nothing gained.

 

[Woodsplitter67]

Anyone dabble with the clear poly carbonate panels? I would imagine it would have the same effect. I was thinking of building a solar kiln to dry rough sawn boards. The solar kilns I have seen are all painted black interiors with clear panels on the southern exposure side. Wouldn't this same concept work but for firewood? I'm just kind of thinking out loud but wouldn't mind input from you guys. I mean nothing venture nothing gained.

i just built a polly carb greenhouse for my son.. basically your building a greenhouse and putting wood in it. the pollycarb works great and it really gets warm in there.. u can use polly for what you want to do.. i did mine in the 8mm panels

 

[Woodsplitter67]

Anyone dabble with the clear poly carbonate panels? I would imagine it would have the same effect. I was thinking of building a solar kiln to dry rough sawn boards. The solar kilns I have seen are all painted black interiors with clear panels on the southern exposure side. Wouldn't this same concept work but for firewood? I'm just kind of thinking out loud but wouldn't mind input from you guys. I mean nothing venture nothing gained.

post 51 has a pick of the temp in the greenhouse with the RH also

 

[Chas0218]

i just built a polly carb greenhouse for my son.. basically your building a greenhouse and putting wood in it. the pollycarb works great and it really gets warm in there.. u can use polly for what you want to do.. i did mine in the 8mm panels

Good to know Maybe I'll just build a greenhouse. My wife has talked about it for a while we just haven't dove in. I'd like to build it big enough to drive a tractor with forks in and pick up a stack then put in a new one. You've really got me thinking about a hoophouse style greenhouse. We have a spot at the bottom of our hill in the valley that gets sun 1st and last of the day.

 

[peakbagger]

HomeDepot in my area stocks the UV resistant polycarbonate panels. I have been tempted to do a hybrid kiln one of these days with polycarbonate on the sunny side and then regular plastic film on the shady sides. I have to be careful that whatever I build is not a "permanent structure" as our local tax assessor will slap a value on it. I already put roofing over my stacks that is supported by two by fours screwed into the ends of firewood with three "rafters" running from the front to back of the stack so expect I could argue that as long as its on pallets and the supports are off the actual stacked firewood I should be okay. My guess is polycarbonate on the roof with some low pitch with a sheet to two of polycarbonate on the front with a slight overhang from the roof over the vertical walls and an adjustable gap between the top of the wall and the roof. Years ago I saw thermal temp dampers that didn't require power to vent greenhouses but the ones I find on the web look too big.

The trade off for polycarbonate sheets is they add infiltration compared to continuous wrap of plastic.

 

[weatherguy]

Good to know Maybe I'll just build a greenhouse. My wife has talked about it for a while we just haven't dove in. I'd like to build it big enough to drive a tractor with forks in and pick up a stack then put in a new one. You've really got me thinking about a hoophouse style greenhouse. We have a spot at the bottom of our hill in the valley that gets sun 1st and last of the day.

I bet a hoop style greenhouse would work great, I'd like to build one that could withstand winter snow and less moving of wood.

 

[Vikestand]

Dude I am jealous of your view!

 

[spudman99]

Slightly off topic but related. I just built this wood rack with polycarbonate roof. Used pallets and 2x4's. With a bit of blocking on the base to make a pallet slightly wider than the double stacks, this could be modified to secure poly on all sides. HD sells the panels at $11 for an 8' length that is 24" wide. Could probably make a full greenhouse for under $75 out the door.

 

[Woodsplitter67]

Slightly off topic but related. I just built this wood rack with polycarbonate roof. Used pallets and 2x4's. With a bit of blocking on the base to make a pallet slightly wider than the double stacks, this could be modified to secure poly on all sides. HD sells the panels at $11 for an 8' length that is 24" wide. Could probably make a full greenhouse for under $75 out the door.

View attachment 253391 View attachment 253392 View attachment 253393

what your using is not whats to be used for a greenhouse... a greenhouse pollycarb is a 2 wall polly sheet. what you have is different material

 

[spudman99]

what your using is not whats to be used for a greenhouse... a greenhouse pollycarb is a 2 wall polly sheet. what you have is different material

You are correct and thanks. What I used was a polycarbonate plastic panel from Lowes.

 

[SpaceBus]

You are correct and thanks. What I used was a polycarbonate plastic panel from Lowes.

View attachment 253472

How well do you think it will handle the snow?

 

[Woodsplitter67]

How well do you think it will handle the snow?

i found the polly carb panels to be quite ridged.. but this is for a thicker panel.. so the 2mm is not as ridged as an 8mm both are double wall..

 

[spudman99]

How well do you think it will handle the snow?

Dunno yet. I have the panels on a 5% slope with a 2x4 cross beam. In full sun I'm hoping the snow pack will melt it off quicker. I have the wood stacked tight to the top so the cross beams should not sag with snow weight. Panels are cut in half so it takes 2 panels for a full 8' crib. Haven't had any decent snow around here yet.