Solar kiln for hardwoods part deux

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.

jaoneill

Feeling the Heat
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?
Single layer of 4 mil over rounded top, corners tacked with stapler to hold in place while I wrapped the sides. Shrink wrap overlapped about by half, so effectively double. One 10x50 roll and a little bit of poly; roll was about $40, one 18"X1000' roll of shrink-wrap and a little bit. I think the 4 roll case of shrink wrap was about $50, and the dispenser $25 +/-. One pic shows the first few individually wrapped this, second one the start of last year's 2-4 pallets in one kilns

IMG_1033.jpg IMG_0910.JPG
 

jaoneill

Feeling the Heat
An interesting update: we brought another three skids into the woodshed the other day, one of which turned out to be somewhat problematic. This one contains primarily smooth bark hickory, especially near the top of the stacks. I thought the splits seemed a bit heavy but hickory is heavy relative to sugar maple or beech so it didn't concern me, then I found the boiler struggling to keep up with the demand for heat. Still didn't quite connect the dots until I threw in some maple this morning and the boiler immediately shot up to the shutdown point, then maintained temp with the outside temp at -10f.
So, this particular hickory tree, for whatever reason, even with its splits being at or near the top of the stack in the "kiln", only dried down to 18%-20%, as opposed to the maple at the bottom of the same skid that is at 10%-12%; go figure. In the two years that I have used this process I have never seen this type of discrepancy.
 

Woodsplitter67

Minister of Fire
Jan 19, 2017
1,967
Woolwich nj
I am really interested in your simple setup for red oak. Do you think if I set this up in the spring I can get the red oak to less than 20% by fall?

Yes.. I think you'll be ok.. You will need to split your wood soon and stack it and top cover untill early june.. zip check the kiln at the end of August and see where your at.. you may need to go into September..
 
  • Like
Reactions: jaoneill

jaoneill

Feeling the Heat
I am really interested in your simple setup for red oak. Do you think if I set this up in the spring I can get the red oak to less than 20% by fall?
I agree with woodsplitter's comment that you should be ok. This is my second year with the kiln project and as I said above, the first time this has happened that I am aware of. This is an ongoing learning process and slightly different for each of us as location, wood, and appliance type are all contributing factors to the experience. I have learned that my gasification boiler does best with maple or beech. Due to how they burn and coal up the fire will keep the "nozzles" nicely covered with coals, maximizing the combustion of all of the gases. Hickory and elm will be reduced to ashes without falling down the sloping floor of the upper chamber to cover the nozzles, often forming a hard "crust" that will prevent splits from "falling" into the burn zone and often block the nozzles completely. This is all magnified if the splits are over 15% and gets worse as moisture level goes up. My ideal burn seems to be achieved with, in order of efficiency, sugar maple, beech, and cherry (all of which I have virtually an endless supply of) under 15% moisture. Not to say that I don't or won't burn other species, but these three are definitely the easiest to burn and hold a good fire with.
 

MR. GLO

Member
Jan 26, 2021
136
Massachusetts
Im thinking its going to be about 14 to 18%.
I did a kiln 2 years ago and left it in there to long.. i started in at this time and opened the kiln in october my oak was like 8% and the cherry was at 2%.... wayyyyyy to dry.. 60 days will be plenty...
Nice setup. The problem with buying kiln dry wood in my area is the larger logs when split and tested have a much different reading and failed at 26 percent. Did you have any large logs over 18 percent?
 

Woodsplitter67

Minister of Fire
Jan 19, 2017
1,967
Woolwich nj
Nice setup. The problem with buying kiln dry wood in my area is the larger logs when split and tested have a much different reading and failed at 26 percent. Did you have any large logs over 18 percent?

I am not drying logs. I dry my splits that go into my stove. The larger being 5x5 inches to the smaller stuff 1.5x1.5 all lengths to 18 inches. All of my stuff was 18%MC or less
 
  • Like
Reactions: MR. GLO

MoDoug

Minister of Fire
Feb 3, 2018
583
NE Missouri
This will be my kiln, it's exactly like my other wood stacks, except it's oriented N/S and in a location that will receive full sun from about noon till sundown. I did build a taller 2x4 into the ends and allowed space in the middle for more, these will support my horizontal boards that my clear plastic will drape over. It's 24' long, and will hold about 2.4 cords. It's almost all red oak on the visible side, with white oak, maple, ash, black oak and hickory on the other.
1615523274512.jpeg
 

Woodsplitter67

Minister of Fire
Jan 19, 2017
1,967
Woolwich nj
This will be my kiln, it's exactly like my other wood stacks, except it's oriented N/S and in a location that will receive full sun from about noon till sundown. I did build a taller 2x4 into the ends and allowed space in the middle for more, these will support my horizontal boards that my clear plastic will drape over. It's 24' long, and will hold about 2.4 cords. It's almost all red oak on the visible side, with white oak, maple, ash, black oak and hickory on the other.
View attachment 276244

that looks good.. just as a heads up.. you can go 3 or 4 splits wide if you want.. when are u going to wrap it.. your going to top cover this untill your ready to wrap.. correct
 

Rob_Red

Feeling the Heat
Feb 2, 2021
292
Southern New England
This will be my kiln, it's exactly like my other wood stacks, except it's oriented N/S and in a location that will receive full sun from about noon till sundown. I did build a taller 2x4 into the ends and allowed space in the middle for more, these will support my horizontal boards that my clear plastic will drape over. It's 24' long, and will hold about 2.4 cords. It's almost all red oak on the visible side, with white oak, maple, ash, black oak and hickory on the other.
View attachment 276244
looks great I'm going to start on mine this weekend. Do you plan to burn that wood this coming season?
 

MoDoug

Minister of Fire
Feb 3, 2018
583
NE Missouri
@Woodsplitter67 Good to know about going 3 or 4 splits wide, the plan is for this to get me through next season, after that I'll be good to go for about 5 years without kilning. My plan on this went slightly awry when I didn't collect as much dead wood as planned, the dead red oak is anywhere from 23 - 28% MC. So I ended up loading the back side with all green wood. I'm sure the seasoning times will vary. I wish the green wood was on the west side, but it isn't. If the red oak reaches 18+- MC, I may unwrap it, and rewrap just the green wood. I plan on wrapping it about June 1st, I'll check the MC and monitor it during the summer. It'll work out.

And yes, I will top cover soon, maybe even today.

@Rob_Red , yes, this will be for next season. Let us know how it goes for you.
 

MoDoug

Minister of Fire
Feb 3, 2018
583
NE Missouri
I got the top cover done. I had some leftover 6 mil plastic sheeting from a vapor barrier job, it's not what I want long term, but it will work for now. It's coming off in June anyway.

1615613149215.jpeg
 

JohnWW

Member
Jul 8, 2019
61
63119
Experimental kiln. Pallet slats on all corners to make a void to build up heat. From the pic it looks like there are gaps but the pallet wrap is continuous apart from a gap at the bottom. Interestingly the wrap withstood substantial and sustained winds for a couple of days and it was the tar paper roof that got trashed by the wind. The wrap flexed like a spiderweb and accidentally I have wind activated venting. Will rebuild with better roof substrate. Wrap is HD 15”.
 

Attachments

  • 1FBDB588-E770-48D7-B4FB-9CC74FA7EA21.jpeg
    1FBDB588-E770-48D7-B4FB-9CC74FA7EA21.jpeg
    317.9 KB · Views: 89

Woodsplitter67

Minister of Fire
Jan 19, 2017
1,967
Woolwich nj
Experimental kiln. Pallet slats on all corners to make a void to build up heat. From the pic it looks like there are gaps but the pallet wrap is continuous apart from a gap at the bottom. Interestingly the wrap withstood substantial and sustained winds for a couple of days and it was the tar paper roof that got trashed by the wind. The wrap flexed like a spiderweb and accidentally I have wind activated venting. Will rebuild with better roof substrate. Wrap is HD 15”.

keep the top clear and.make sure you vent it right away. it's a little early to start the kiln.. how long ago was it split
 
  • Like
Reactions: JohnWW

JohnWW

Member
Jul 8, 2019
61
63119
keep the top clear and.make sure you vent it right away. it's a little early to start the kiln.. how long ago was it split
Thanks. Split last week but 5 ft logs stored of ground for 2 summers. Half rounds and rounds mostly. Mostly wanting to see how the thin wrap would hold up. I have other stacks of splits that I will wrap too when I have my technique down.
 

Woodsplitter67

Minister of Fire
Jan 19, 2017
1,967
Woolwich nj
Thanks. Split last week but 5 ft logs stored of ground for 2 summers. Half rounds and rounds mostly. Mostly wanting to see how the thin wrap would hold up. I have other stacks of splits that I will wrap too when I have my technique down.

I'd wait on wrapping the wood untill early June. That wood is wet and needs to dry some prior to you starting the kiln.. if you wrap I now you'll have trouble drying it out..you'll know it's ready when the stack starts to shift
 
  • Like
Reactions: mcdougy