Solar kiln for hardwoods part deux

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Woodsplitter67

Minister of Fire
Jan 19, 2017
1,967
Woolwich nj
Does the wood take on any moisture if you get it down to single digit moisture content? As in the beech that you took to 2% , did it come back up? I'm assuming too low of mc causes wood to burn faster and affects overnight burns?

Yes the wood will take on some moisture. The cherry that I had at sub 3% and well.as the oak all took on some moisture. When you take apart the kiln you will be removing the wood from its arid environment to your local environment. we get alot of humidity here so the wood did go up.. but not alot. when I checked the splits they went from low single digits to low teens. That being said your not going to have to worry about your wood going to 20%mc.. unless your wood gets wet.. This is what you will need to look out for
Your wood in the single digits will catch quicker, it will burn hotter. It will catch quicker because is super dry. It will burn hotter because the wood has less moisture in it. Moisture in the wood cools the fire process. so if your burning wood at 3% and im burning wood at 20% I will have 17% more moisture by weight.. This is why wet wood is hard to catch and smolder. You will just need to keep an eye no the stove as it may get up to temp quicker.... as for burn time I did not notice the lenth of my overnight change.. I still got quality overnight burns..
 
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mcdougy

Minister of Fire
Apr 15, 2014
676
ontario
Yes the wood will take on some moisture. The cherry that I had at sub 3% and well.as the oak all took on some moisture. When you take apart the kiln you will be removing the wood from its arid environment to your local environment. we get alot of humidity here so the wood did go up.. but not alot. when I checked the splits they went from low single digits to low teens. That being said your not going to have to worry about your wood going to 20%mc.. unless your wood gets wet.. This is what you will need to look out for
Your wood in the single digits will catch quicker, it will burn hotter. It will catch quicker because is super dry. It will burn hotter because the wood has less moisture in it. Moisture in the wood cools the fire process. so if your burning wood at 3% and im burning wood at 20% I will have 17% more moisture by weight.. This is why wet wood is hard to catch and smolder. You will just need to keep an eye no the stove as it may get up to temp quicker.... as for burn time I did not notice the lenth of my overnight change.. I still got quality overnight burns..
So essentially , you can not leave the wood too long in the kiln in your opinion? Or "over dry" it.
 

neverbilly

Burning Hunk
Dec 27, 2015
158
Arkansas, USA
@Woodsplitter67 ... summers here are hot and sometimes unreal hot. June through September is summer hot and even through October 15. We usually have a drought period July through September and in most years, some or a lot of that exceeds 100 degrees. I am wondering if one could get two decent kiln drying sessions. Such as... June 1 through July 31 (two months) and remove the kiln and stack/deliver it elsewhere. Then another session in the same rack August 1 through September 30. Thinking being that if you could reduce moisture a decent amount in two months and do it twice/summer, you could double your output. I sell some firewood, so, this is what I am thinking of. Realize that no sellers around here sell seasoned firewood. They often say it is but it's seasoned after splitting 3-6 months, that's it. So, if I could give somebody wood that is even 25-30% MC, that's good! What do you think?
 
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Woodsplitter67

Minister of Fire
Jan 19, 2017
1,967
Woolwich nj
So essentially , you can not leave the wood too long in the kiln in your opinion? Or "over dry" it.

The way I do it is U try to hit a target MC. The first year I over dried it was my first run. I really didn't think about over seasoning . You can cut a flap and pull one out and test here and there. I shoot for like 12 to 15%MC
 

Woodsplitter67

Minister of Fire
Jan 19, 2017
1,967
Woolwich nj
@Woodsplitter67 ... summers here are hot and sometimes unreal hot. June through September is summer hot and even through October 15. We usually have a drought period July through September and in most years, some or a lot of that exceeds 100 degrees. I am wondering if one could get two decent kiln drying sessions. Such as... June 1 through July 31 (two months) and remove the kiln and stack/deliver it elsewhere. Then another session in the same rack August 1 through September 30. Thinking being that if you could reduce moisture a decent amount in two months and do it twice/summer, you could double your output. I sell some firewood, so, this is what I am thinking of. Realize that no sellers around here sell seasoned firewood. They often say it is but it's seasoned after splitting 3-6 months, that's it. So, if I could give somebody wood that is even 25-30% MC, that's good! What do you think?

I think your way south of me. You could start a kiln May first through October. You could do 2 kiln runs.. me personally I don't like to move wood if I dont have to.. so I would do a. large kiln. you could easily do it with 3.. 32ft racks and do over 4 cords in 1 shot. Iv sold some of my wood at a super premium price.. I sold 2 cords for 800 and they came and picked it up.. If I were you I would only sell premium wood You could get it down to the teens in that time.. Separate your self form the others that sell sup par wood
 
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ClintonH

Burning Hunk
Jan 4, 2014
118
NW OH
I think your way south of me. You could start a kiln May first through October. You could do 2 kiln runs.. me personally I don't like to move wood if I dont have to.. so I would do a. large kiln. you could easily do it with 3.. 32ft racks and do over 4 cords in 1 shot. Iv sold some of my wood at a super premium price.. I sold 2 cords for 800 and they came and picked it up.. If I were you I would only sell premium wood You could get it down to the teens in that time.. Separate your self form the others that sell sup par wood

Depending on the design, could 2 stationary stacks be dried in your 2 runs: just move/rebuild the kiln around the 2nd stack when it was ready to be dried?
 

Woodsplitter67

Minister of Fire
Jan 19, 2017
1,967
Woolwich nj
Depending on the design, could 2 stationary stacks be dried in your 2 runs: just move/rebuild the kiln around the 2nd stack when it was ready to be dried?

Are u trying to do a kiln around a single stack.. what is the lenth and with of what you want to do
 

showrguy

Minister of Fire
Aug 2, 2015
520
Marysville, Pa.
Woodsplitter, would you say there is a limit to how big you can make one of these kilns ?
I’m in the woods, so I can’t have full sun all day long, but have several hours a day..
I think all summers worth of heat cycles should get me there..
I was gonna do 4-6 cords in one wrap, unless you tell me not to . .
 

Woodsplitter67

Minister of Fire
Jan 19, 2017
1,967
Woolwich nj
Woodsplitter, would you say there is a limit to how big you can make one of these kilns ?
I’m in the woods, so I can’t have full sun all day long, but have several hours a day..
I think all summers worth of heat cycles should get me there..
I was gonna do 4-6 cords in one wrap, unless you tell me not to . .

I dont think there is a limit. I think the limit is when you run out of clear plastic. If your not in full sun all day I would give your self alot of time. I would to a test kiln the first year and see how hot you can get it. Id set your kiln up in early to mid June and let it go through October... Id put it in the sunniest spot that I could fined..
 

showrguy

Minister of Fire
Aug 2, 2015
520
Marysville, Pa.
I dont think there is a limit. I think the limit is when you run out of clear plastic. If your not in full sun all day I would give your self alot of time. I would to a test kiln the first year and see how hot you can get it. Id set your kiln up in early to mid June and let it go through October... Id put it in the sunniest spot that I could fined..
Welp, I sort of did a test 2 years ago..
I had a load of hickory on my dump trailor parked in my driveway, covered it with clear plastic for a few weeks, was seeing 135 deg. pretty much every sunny day... oh, it had a vent cut in it..
I have heavy plastic that came off of a 20-24 x 36 greenhouse thats in nice shape
 

Woodsplitter67

Minister of Fire
Jan 19, 2017
1,967
Woolwich nj
Welp, I sort of did a test 2 years ago..
I had a load of hickory on my dump trailor parked in my driveway, covered it with clear plastic for a few weeks, was seeing 135 deg. pretty much every sunny day... oh, it had a vent cut in it..
I have heavy plastic that came off of a 20-24 x 36 greenhouse thats in nice shape
ok.. if you can get it that warm and have no moisture build up.. thats great.. go for it.. Check your MC every once in a while..
 

Woodsplitter67

Minister of Fire
Jan 19, 2017
1,967
Woolwich nj
What do you mean by no moisture build up exactly? Should the plastic be mostly dry inside? Or what signs should you look for?

You may have some moisture inside on the plastic the first couple days. after that.. the inside of the kiln should not really have any moisture on the inside. If moisture persist then you may need to vent more.
 

andym

Feeling the Heat
Feb 6, 2020
434
Hicksville, Ohio
You may have some moisture inside on the plastic the first couple days. after that.. the inside of the kiln should not really have any moisture on the inside. If moisture persist then you may need to vent more.
That makes sense. I tried kiln drying some sugar maple this summer. I didn't have enough vents (according to the above), and made a few other errors. The upper part of the stack was bone dry. I didn't test too many pieces from down lower but sine were still too wet. I won't need it this year anyway so it was good lessons learned. I will try another this summer.
 

Woodsplitter67

Minister of Fire
Jan 19, 2017
1,967
Woolwich nj
That makes sense. I tried kiln drying some sugar maple this summer. I didn't have enough vents (according to the above), and made a few other errors. The upper part of the stack was bone dry. I didn't test too many pieces from down lower but sine were still too wet. I won't need it this year anyway so it was good lessons learned. I will try another this summer.

this is why I like to try things.. its a learning experience.. My first kiln was only a cord.. and I baked the wood to like 2%.. from there its been 2+ cords and a target MC.. I now have the experience to do a full yeas worth in 1 run if I wanted.. Ill probably never do it.. but if something happens and I need to dry wood in 1 summer I can
 
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Poindexter

Minister of Fire
Jun 28, 2014
2,382
Fairbanks, Alaska
I am drying 8 cords at a time up here. I did overshoot/ overkiln one year and it sucked, it was all the wood I had to burn.

I _think_ I could do two kiln loads annually. I get about 22 hours of daylight at summer solstice, the sun rises over the horizon at something like 5 degrees east of north and then dips back below the horizon at something like 10 degrees west of north 22 hours later. Then two hours of "civil twilight" and Mr. Sun pops back above the horizon line again.

If I had four cords up in the kilns on Saint Patrick's Day and had them down to FSP on May 1 (easy) they would likely be around 13-15% on solstice, but I would have to take them out of the kilns, stack them somewhere else off the ground and covered on top and bring in another 4 green cords and have them stacked mui pronto.

The sticking point is having the solstice time load of green wood delivered timely so I can get it in the kilns. Up here every day counts trying to get two loads through. If my vendor isn't taking my calls I am probably screwed.

I have filled a kiln after solstice and gotten under 20% MC before freeze up, but it was a lot of fussing. And no way do I want to handle four cords of wood an extra time every year. I typically have green splits dropped in my driveway in Mar-Apr-May, handle them once to get them into the kilns, then in heating season bring them to the garage by sled about a face cord ( four sled loads) at a time, and then bring them from the garage to the stove with a canvas tote in my bunny slippers and bathrobe.

For handling split cordwood by hand I think the annual limit for a middle aged man in good health with a good metabolic rate is about 10-15 cords per year. More than that, you are going to need some kind of basket system and a forklift or telehandler. And a dump bed on your truck.

No way could I kiln eight cords in the spring, sell those, bring in eight more green cords, get them dry enough to burn good before freeze up, and then run wood in my stove over the winter while refilling the kilns with green wood to sell next summer, without equipment. I could afford the whisky and motrin required to do that by hand, but I wouldn't be sober enough long enough to keep my day job.
 

Woodsplitter67

Minister of Fire
Jan 19, 2017
1,967
Woolwich nj
I am drying 8 cords at a time up here. I did overshoot/ overkiln one year and it sucked, it was all the wood I had to burn.

I _think_ I could do two kiln loads annually. I get about 22 hours of daylight at summer solstice, the sun rises over the horizon at something like 5 degrees east of north and then dips back below the horizon at something like 10 degrees west of north 22 hours later. Then two hours of "civil twilight" and Mr. Sun pops back above the horizon line again.

If I had four cords up in the kilns on Saint Patrick's Day and had them down to FSP on May 1 (easy) they would likely be around 13-15% on solstice, but I would have to take them out of the kilns, stack them somewhere else off the ground and covered on top and bring in another 4 green cords and have them stacked mui pronto.

The sticking point is having the solstice time load of green wood delivered timely so I can get it in the kilns. Up here every day counts trying to get two loads through. If my vendor isn't taking my calls I am probably screwed.

I have filled a kiln after solstice and gotten under 20% MC before freeze up, but it was a lot of fussing. And no way do I want to handle four cords of wood an extra time every year. I typically have green splits dropped in my driveway in Mar-Apr-May, handle them once to get them into the kilns, then in heating season bring them to the garage by sled about a face cord ( four sled loads) at a time, and then bring them from the garage to the stove with a canvas tote in my bunny slippers and bathrobe.

For handling split cordwood by hand I think the annual limit for a middle aged man in good health with a good metabolic rate is about 10-15 cords per year. More than that, you are going to need some kind of basket system and a forklift or telehandler. And a dump bed on your truck.

No way could I kiln eight cords in the spring, sell those, bring in eight more green cords, get them dry enough to burn good before freeze up, and then run wood in my stove over the winter while refilling the kilns with green wood to sell next summer, without equipment. I could afford the whisky and motrin required to do that by hand, but I wouldn't be sober enough long enough to keep my day job.

always a good read..
 

Adabiviak

Feeling the Heat
Dec 7, 2008
362
Sierra Nevadas, California
What happens if the wood is too dry? I mean, it burns hotter, but wouldn't that translate to needing less wood to maintain operating temperature, plus the burn would be much cleaner?
 

Woodsplitter67

Minister of Fire
Jan 19, 2017
1,967
Woolwich nj
What happens if the wood is too dry? I mean, it burns hotter, but wouldn't that translate to needing less wood to maintain operating temperature, plus the burn would be much cleaner?

I dont monitor my emissions..
 

mcdougy

Minister of Fire
Apr 15, 2014
676
ontario
I am drying 8 cords at a time up here. I did overshoot/ overkiln one year and it sucked, it was all the wood I had to burn.

I _think_ I could do two kiln loads annually. I get about 22 hours of daylight at summer solstice, the sun rises over the horizon at something like 5 degrees east of north and then dips back below the horizon at something like 10 degrees west of north 22 hours later. Then two hours of "civil twilight" and Mr. Sun pops back above the horizon line again.

If I had four cords up in the kilns on Saint Patrick's Day and had them down to FSP on May 1 (easy) they would likely be around 13-15% on solstice, but I would have to take them out of the kilns, stack them somewhere else off the ground and covered on top and bring in another 4 green cords and have them stacked mui pronto.

The sticking point is having the solstice time load of green wood delivered timely so I can get it in the kilns. Up here every day counts trying to get two loads through. If my vendor isn't taking my calls I am probably screwed.

I have filled a kiln after solstice and gotten under 20% MC before freeze up, but it was a lot of fussing. And no way do I want to handle four cords of wood an extra time every year. I typically have green splits dropped in my driveway in Mar-Apr-May, handle them once to get them into the kilns, then in heating season bring them to the garage by sled about a face cord ( four sled loads) at a time, and then bring them from the garage to the stove with a canvas tote in my bunny slippers and bathrobe.

For handling split cordwood by hand I think the annual limit for a middle aged man in good health with a good metabolic rate is about 10-15 cords per year. More than that, you are going to need some kind of basket system and a forklift or telehandler. And a dump bed on your truck.

No way could I kiln eight cords in the spring, sell those, bring in eight more green cords, get them dry enough to burn good before freeze up, and then run wood in my stove over the winter while refilling the kilns with green wood to sell next summer, without equipment. I could afford the whisky and motrin required to do that by hand, but I wouldn't be sober enough long enough to keep my day job.

What species of wood are you drying? What were the consequences of having overkilned wood. Im guessing short burn times? How much shorter?
Maybe you could consider coaching a youth sports team and convince them that carrying wood from one pile to another is essential to their overall training? Lead by example and once you make 3 trips back and forth fake an injury, then start sipping on your whiskey??? I think it would work :)
 

Eric Minnis

New Member
Dec 25, 2020
34
NC
Seems like the IBC totes would be a very simple candidate for a solar kiln with the greenhouse plastic. I got 10 of those bulk storage mesh ventilated firewood bags to try this year and I may try to rig up a simple kiln with those. They are on pallets on dry ground. I bet the plastic wrap method would work once I figured out the vent size.
 

Poindexter

Minister of Fire
Jun 28, 2014
2,382
Fairbanks, Alaska
What species of wood are you drying? What were the consequences of having overkilned wood. Im guessing short burn times? How much shorter?
Maybe you could consider coaching a youth sports team and convince them that carrying wood from one pile to another is essential to their overall training? Lead by example and once you make 3 trips back and forth fake an injury, then start sipping on your whiskey??? I think it would work :)


Spruce. White spruce and black spruce. Too dry it goes hot and fast. Too hot and too fast. I coach my church's youth BBQ team, much more my speed.
 
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jaoneill

Feeling the Heat
Update on this years kiln process. With the price of poly I looked for a less costly alternative and bought a case of 18" shrinkwrap and a roller/dispenser. I wrapped the pallets individually with a "cap" of 4 mil poly and shrink wrapped sides. I only needed just over a 50' roll of 10' poly and one roll and a bit of shrink-wrap to cap twenty two pallets with +/- 1/2 cord of 2' splits on each one. As I have indicated previously, my primary goals are well seasoned (15% or less) wood and minimal handling. With each pallet a stand alone kiln the splits are dried and covered until needed. I shift 5-6 wrapped pallets into the woodshed adjacent to the boiler room and take the plastic off as wood is needed. I only handle the wood twice; from splitter to pallet and from pallet to boiler. This year's wood is hickory, sugar maple and beech that had been down, in log length for about a year. Was mostly wrapped from mid July to mid August with a few later pallets done around the beginning of Sept. Moisture content on what I have been burning ranges from 8%-14% depending on species and location (top or bottom) in pallet stack. The later wrapped units are 17%-19%, still not too bad but I may not need them this year.
Pic is after the first couple of days of processing.
 

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neverbilly

Burning Hunk
Dec 27, 2015
158
Arkansas, USA
Update on this years kiln process. With the price of poly I looked for a less costly alternative and bought a case of 18" shrinkwrap and a roller/dispenser. I wrapped the pallets individually with a "cap" of 4 mil poly and shrink wrapped sides. I only needed just over a 50' roll of 10' poly and one roll and a bit of shrink-wrap to cap twenty two pallets with +/- 1/2 cord of 2' splits on each one. As I have indicated previously, my primary goals are well seasoned (15% or less) wood and minimal handling. With each pallet a stand alone kiln the splits are dried and covered until needed. I shift 5-6 wrapped pallets into the woodshed adjacent to the boiler room and take the plastic off as wood is needed. I only handle the wood twice; from splitter to pallet and from pallet to boiler. This year's wood is hickory, sugar maple and beech that had been down, in log length for about a year. Was mostly wrapped from mid July to mid August with a few later pallets done around the beginning of Sept. Moisture content on what I have been burning ranges from 8%-14% depending on species and location (top or bottom) in pallet stack. The later wrapped units are 17%-19%, still not too bad but I may not need them this year.
Pic is after the first couple of days of processing.

Do you know your plastic costs for those 22 pallets? That is 11 cords, a lot! I am curious how you do your wrapping. Is your wood stacked flat on top or rounded top? You put the 4mil poly on the top? How? You just wrap round and round the bottom with the shrink wrap? Wrap just one layer thick? Is all of this enclosed or is there any venting?
 
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