Solar tarping

hearth_heat

New Member
Jun 19, 2020
9
Piedmont, NC
Hi,

I'm a new wood burner with an old fireplace insert. I'm wanting to get really dry wood for burning this year.

A tree guy dropped off three loads - two bradford pear and one black maple. Both great burners but need a lot of seasoning.

I bought a used splitter and have carved up 2/3rds of the wood, and I have 8 pallets ready for stacking. I've reviewed a lot of information about round vs cross-stacking, but I'm mostly concerned about getting some of my wood ready for this fall.

I've seen a lot of very interesting information about solar kilns and I'd like to try it. Rather than building a large frame and using transparent greenhouse film, I was thinking that wouldn't be necessary because the light requirement isn't needed to dry firewood - only the heat.

And so, if I used a dark tarp in place of the clear film, wouldn't that give me the heat I'm looking for at a lesser cost, (all other things being equal?)

Thanks for the help!
 

Bad LP

Minister of Fire
Nov 28, 2014
1,147
Northern Maine
I asked the same question a while back and was told that they really liked the more clear plastic. I didn't argue the point but had been thinking that the black would get the stack really hot.

I have a well ventilated shed and had been thinking on wrapping it. In the end I did nothing.
 

peakbagger

Minister of Fire
Jul 11, 2008
5,297
Northern NH
I currently am using black plastic over a electrical conduit frame work. The conduit is set outside the stack about 2 to 3". So far it seems to be doing what it needs to. I have two 6" diameter holes on the end of the cover up on the high ends Yes It does get hot and if I block the holes it gets damp inside really quick which implies its dryng.
 

hearth_heat

New Member
Jun 19, 2020
9
Piedmont, NC
That's what I'm thinking. People typically use clear film when building greenhouses because they need the light for photosynthesis. But a wood-stack only needs the heat.

I like your idea of putting two vent holes at one end to let the moist air escape, because the key issue is venting.

In fact, I like the idea of using a tarp like a pup tent and angling one end up higher to allow the heated air to move upwards and out, (rather than just having it sit and condense when the sun goes down.)

Because if you're going to be collecting hot, moist air, you've got to have a way to vent it, (which is the problem with covering the stack completely.)

I think that covering just the top is good, but I think that venting that air out is even better.

And if you've got hot air rising, then why not use that to get a siphon going that draws cool air in from the bottom and maximizes both temp and airflow?

So that's why I'm thinking a dark tarp will work better, (and be cheaper,) for this than a clear film.
 

Woodsplitter67

Minister of Fire
Jan 19, 2017
1,251
Woolwich nj
your theory of the greenhouse operation is actually incorrect. clear plastic is used for a number of reasons.. yes to allow for photosynthesis, but your missing that the light heats the inside the greenhouse and the plastic holds the heat in.. what your saying is the light heats the plastic and the plastic heats the inside of the greenhouse which is incorrect. for your kiln to operate at its best you need to let the light in to heat the inside.
think about this.. in Florida.. what is the purpose of tinted windows.. a tinted window allows less light in keeping the interior of the car cooler.. by your thoughts.. it would actually heat the interior.. but we know it doesn't work that way..check out the 2 links in my signature
 

hearth_heat

New Member
Jun 19, 2020
9
Piedmont, NC
Okay! This is the information I'm looking for.

Now the consideration is between the dark tarp for it's cheaper cost vs the transparent film for it's better performance. (The goal simply being to get my freshly split firewood to =<20% by October.)

A friend says they'll get there just split and in a pile, but I don't want to chance it. That's why I'll stack and cover some and leave the rest in the pile, and use my moisture meter to see which works the best.
 
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Woodsplitter67

Minister of Fire
Jan 19, 2017
1,251
Woolwich nj
Okay! This is the information I'm looking for.

Now the consideration is between the dark tarp for it's cheaper cost vs the transparent film for it's better performance. (The goal simply being to get my freshly split firewood to =<20% by October.)

A friend says they'll get there just split and in a pile, but I don't want to chance it. That's why I'll stack and cover some and leave the rest in the pile, and use my moisture meter to see which works the best.
cheap 6mil cleared plastic at the big box store will run you less that 25 bucks.. 50 for a medium roll.. large tarps.are more expensive than that... why not just go with the clear get the better performance out of it and be done.. its not like your saving 300 bucks by going with the tarp..I think your over Analyzing this..
 

hearth_heat

New Member
Jun 19, 2020
9
Piedmont, NC
But I like to over-analyze!

Seriously, I'm just looking to get the best performance for the money, because if you're going to invest in something, it should provide more benefit than cost.

Also, I was looking for those links you mentioned in your profile and I couldn't find them. Could you post them?

(Oh, I see them now on my desktop. I couldn't see them on my phone.)
 
Last edited:

andym

Member
Feb 6, 2020
142
Hicksville, Ohio
I'm currently running 3 test kilns. I used a roll of pallet stretch wrap. 20 inches by 1000 feet. The roll was under 20 bucks at menards. I wrapped two pallets plus another 14ft long stack, and there's still some left. It seems to be doing the job. 5 weeks now and none has fallen off or anything. I just wrapped the pile as it was. Initially there was a lot of condensation and some naturally ended up on the logs. After a couple weeks there is not a lot of that happening. Can't wait to open it up in a couple months!

The bottom line is that the interior air temp must be higher than outside. As long as some airflow occurs this will dry wood. Clear plastic will work more quickly by providing higher temps.
 

hearth_heat

New Member
Jun 19, 2020
9
Piedmont, NC
But I like to over-analyze!

Seriously, I'm just looking to get the best performance for the money, because if you're going to invest in something, it should provide more benefit than cost.

Also, I was looking for those links you mentioned in your profile and I couldn't find them. Could you post them
I'm currently running 3 test kilns. I used a roll of pallet stretch wrap. 20 inches by 1000 feet. The roll was under 20 bucks at menards. I wrapped two pallets plus another 14ft long stack, and there's still some left. It seems to be doing the job. 5 weeks now and none has fallen off or anything. I just wrapped the pile as it was. Initially there was a lot of condensation and some naturally ended up on the logs. After a couple weeks there is not a lot of that happening. Can't wait to open it up in a couple months!

The bottom line is that the interior air temp must be higher than outside. As long as some airflow occurs this will dry wood. Clear plastic will work more quickly by providing higher temps.
And how have you covered the top?
 

Poindexter

Minister of Fire
Jun 28, 2014
2,177
Fairbanks, Alaska
The main thing to get your wood dry by October is going to be get it split, get it stacked off the ground (I like pallets up on cinder blocks for the money), and get it top covered. Once it is split, stacked and top covered it will start drying.

Play with it at your local place. Black tarp, blue tarp, clear plastic, try some different stuff. One eye opener for me (at my house) was putting a layer of plastic on the top of the pallet before I stacked wood on top of the plastic on top of the pallet, then top covered like the rest of my stacks that year. You can't really start playing with it until you have it at least split and a place to stack it.

The thing about clear plastic is it lets UV light through. UV passes through clear things like the earth's atmosphere unchanged, but when it hits an opaque thing like your forehead or a barn it turns into heat - infrared radiation. Using clear plastic lets UV from the sun through the clear membrane so it heats the wood directly. A black sheet of plastic will get plenty hot, and the air trapped under it will warm up, and that will cause the wood in there to eventually warm up to, but under clear plastic the wood gets zapped directly by the incoming sunbeams.
 
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Woodsplitter67

Minister of Fire
Jan 19, 2017
1,251
Woolwich nj
The main thing to get your wood dry by October is going to be get it split, get it stacked off the ground (I like pallets up on cinder blocks for the money), and get it top covered. Once it is split, stacked and top covered it will start drying.

Play with it at your local place. Black tarp, blue tarp, clear plastic, try some different stuff. One eye opener for me (at my house) was putting a layer of plastic on the top of the pallet before I stacked wood on top of the plastic on top of the pallet, then top covered like the rest of my stacks that year. You can't really start playing with it until you have it at least split and a place to stack it.

The thing about clear plastic is it lets UV light through. UV passes through clear things like the earth's atmosphere unchanged, but when it hits an opaque thing like your forehead or a barn it turns into heat - infrared radiation. Using clear plastic lets UV from the sun through the clear membrane so it heats the wood directly. A black sheet of plastic will get plenty hot, and the air trapped under it will warm up, and that will cause the wood in there to eventually warm up to, but under clear plastic the wood gets zapped directly by the incoming sunbeams.
A word from the master...well spoken
 

brenndatomu

Minister of Fire
Aug 21, 2013
4,998
NE Ohio
but I'm mostly concerned about getting some of my wood ready for this fall.
Better get on it...you are already pushing it time wise, even with a kiln...
 

Woodsplitter67

Minister of Fire
Jan 19, 2017
1,251
Woolwich nj
Better get on it...you are already pushing it time wise, even with a kiln...
Hes in NC so there is time.. as long as he's CSS and wrapped by the 4th of July he'll have wood sub 20%Mc... that is IF the kiln runs correctly. If I was counting on that wood for this year.. I'd do the proven kiln and maybe a test version with a smaller amount of wood..
 
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brenndatomu

Minister of Fire
Aug 21, 2013
4,998
NE Ohio
as long as he's CSS and wrapped by the 4th of July he'll have wood sub 20%Mc
Well, if things go like they go for me when I start a project like this, that's still not much cushion! ;lol
 

hearth_heat

New Member
Jun 19, 2020
9
Piedmont, NC
I used the plastic wrap. It wasn't the easiest to make the top shed water, but I got it accomplished. I don't know if it was the cheapest method, but I didn't have to fold anything or fasten it down.
I like the idea of using stretch wrap around the stack. That takes a couple of minutes and you're done. The wood is going to vent upwards, and if I suspend a tarp over the top like a tent, I can get the thermal chimney effect while keeping the top dry.

I like it. Thanks!
 

andym

Member
Feb 6, 2020
142
Hicksville, Ohio
Just a word of caution though: wrapping something in multiple layers can be a dizzying experience!! It does help hold the stack together as well. Final results are a few months away, but I've read of other guys on this forum that have done it this way.
 

brenndatomu

Minister of Fire
Aug 21, 2013
4,998
NE Ohio
if I suspend a tarp over the top like a tent, I can get the thermal chimney effect while keeping the top dry.
Someone with direct experience can verify...but I think too much ventilation is counter productive with these kilns...
 

hearth_heat

New Member
Jun 19, 2020
9
Piedmont, NC
Here is a very nice article using just wood stacks and pallet wrap. Until the very end of the article, I didn't understand how the wrap would let the stack breathe, but they inserted logs underneath the wraps as "louvers," (which I thought was pretty clever.) Now, the entire stack is wrapped, including the top, and it can vent the moisture easily while keeping the top covered.

(They even have stats!)

 
Last edited:

brenndatomu

Minister of Fire
Aug 21, 2013
4,998
NE Ohio
Here is a very nice article using just wood stacks and pallet wrap. Until the very end of the article, I didn't understand how the wrap would let the stack breathe, but they inserted logs underneath the wraps as "louvers," (which I thought was pretty clever.) Now, the entire stack is wrapped, including the top, and it can vent the moisture easily while keeping the top covered.

(They even have stats!)

Dunno about the kiln aspect, I didn't read on past the beginning where they are very obviously amateur level firewood stackers...never seen anyone try to crib the corners/ends of a firewood stack with rounds before. To me, it makes the rest of the info suspect.
There are a bunch of threads here on hearth where people documented their kiln results...some of them quite in depth and well done...I would tend to want to follows in the steps of someone has already graduated from the school of hard knocks, and not someone who is still finding their way. (like I said, I only read the first part of that article, personally, I have better things to do then read a self appointed social media "expert")
 
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neverbilly

Member
Dec 27, 2015
118
Louisiana, USA
The main thing to get your wood dry by October is going to be get it split, get it stacked off the ground (I like pallets up on cinder blocks for the money), and get it top covered. Once it is split, stacked and top covered it will start drying.

Play with it at your local place. Black tarp, blue tarp, clear plastic, try some different stuff. One eye opener for me (at my house) was putting a layer of plastic on the top of the pallet before I stacked wood on top of the plastic on top of the pallet, then top covered like the rest of my stacks that year. You can't really start playing with it until you have it at least split and a place to stack it.

The thing about clear plastic is it lets UV light through. UV passes through clear things like the earth's atmosphere unchanged, but when it hits an opaque thing like your forehead or a barn it turns into heat - infrared radiation. Using clear plastic lets UV from the sun through the clear membrane so it heats the wood directly. A black sheet of plastic will get plenty hot, and the air trapped under it will warm up, and that will cause the wood in there to eventually warm up to, but under clear plastic the wood gets zapped directly by the incoming sunbeams.
Why do you put pallets on cinder blocks? Why not just on top the pallets? I suppose more circulation underneath.
 

Poindexter

Minister of Fire
Jun 28, 2014
2,177
Fairbanks, Alaska
Why do you put pallets on cinder blocks? Why not just on top the pallets? I suppose more circulation underneath.
Local to me it works best. When we get rain, it rains hard and long. I fiddled with pallets and tarps for years before I built my kilns, my best results (at my house) was cinderblocks, pallets on them, then a plastic sheet covering the pallet, then stack the wood, then top cover.

I built my kilns to stand on the already established cinder blocks.

Part of it is splash zone. Wood close to the ground gets splashed on by subsequent rain drops hitting the puddles and the wood struggles to get dry. Plus it gets dirt on the wood that has to be carried into the house and takes up space in the firebox, and then get carried back out of the house in the ash bucket. No thanks.

The other, I think local to me, is when the sun comes back out and hits the water saturated dirt, a lot of that "ground water" gets re-evaporated into the air. I can see it sometimes if we have a hard rain over night and then bright sun first thing in the morning. It looks like fog rising out of the ground, no stuff.

Bottom line, it works for me at this address.
 

hearth_heat

New Member
Jun 19, 2020
9
Piedmont, NC
Local to me it works best. When we get rain, it rains hard and long. I fiddled with pallets and tarps for years before I built my kilns, my best results (at my house) was cinderblocks, pallets on them, then a plastic sheet covering the pallet, then stack the wood, then top cover.
But you're up in Alaska, right? With an extremely short summer and tons of ground water at that time. Pallets on cinder-blocks with plastic beneath the wood is essential for you.
 

hearth_heat

New Member
Jun 19, 2020
9
Piedmont, NC
Dunno about the kiln aspect, I didn't read on past the beginning where they are very obviously amateur level firewood stackers...never seen anyone try to crib the corners/ends of a firewood stack with rounds before. To me, it makes the rest of the info suspect.
There are a bunch of threads here on hearth where people documented their kiln results...some of them quite in depth and well done...I would tend to want to follows in the steps of someone has already graduated from the school of hard knocks, and not someone who is still finding their way. (like I said, I only read the first part of that article, personally, I have better things to do then read a self appointed social media "expert")
If you'd read a bit further and you'd see he's got thermal and air-flow readings from sensors he put in that stack. VERY convincing.