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Building my first solar kiln

Started by etd66ss, June 14, 2021, 06:29:59 AM

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btulloh

No problem on the air volume. I suppose if your fill in roof is black you'll get some benefit and no need to insulate. Main thing is to get your vents and fans right so air circulation through the stack is correct. 
HM126

etd66ss

Quote from: btulloh on June 20, 2022, 10:53:43 AM
No problem on the air volume. I suppose if your fill in roof is black you'll get some benefit and no need to insulate. Main thing is to get your vents and fans right so air circulation through the stack is correct.
I intend to roof the non-glazed portions with black asphalt shingles.

Nebraska


doc henderson

Menards has poly-carb panels up to 24 feet long, if you have those.
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

etd66ss

Quote from: doc henderson on June 21, 2022, 09:02:01 PM
Menards has poly-carb panels up to 24 feet long, if you have those.
I bought 8 ft panels from Lowes yesterday, so stuck with those.
The closest Menards to my location is about 250 miles and the panels are a special order.
I'll just have to make due with what I have...


 
Not an ideal solar collector, but such is life.
I didn't want to have to buy plywood, but my sawmill is not up and running yet (waiting for some utility poles to be sawn up by another mill to use for my sawmill bed) so can't mill boards for the sheathing/siding.
This thing is costing me way more than I wanted.

etd66ss

I worked on the framing a bit more this past weekend.

Over the winter/spring, the boards I used for the decking (mainly sawn 2x8 white pine which was air dried for about 1 year) swelled and snapped many of the decking screws I used to fasten them down. So the south wall of the kiln was bowed out nearly 2" from the swelling. I had to fix that by taking out all the nails on the south wall, clamping back into place and this time I used SPAX screws on the sill plate. I trimmed the decking that was sticking out with a chainsaw as that is all that I could get in there. It looks ugly but that cut will be covered up anyways. I tried to use my sawsall but that didn't work well.



 

Since I could only buy 8ft Tuftex locally, and my design was to use 12ft, I decided to strengthen up the framing at the ridge of the roof.  Over the winter/spring, the "naked" roof rafters sagged and twisted in the weather. Some of them sagging 2". This extra framing in the roof allowed me to support the rafters better, to the point they only sag about 3/4" in the center of the roof now. This is the first time using air dried framing lumber for a roof of any kind, I should have gone with 2x6 rafters.  I followed the VA Tech plans, but my kiln is about twice the size. 2x4 rafters just are not enough if you want to keep the roof perfectly flat. Too late now, kiln should still work as long as it does not develop leaks in the roof due to a slightly concave roof. At a 50 angle, I think it should be ok in terms of rain/snow.



 


 

The north wall door opening is 8ft tall and 23-1/2ft wide. Prior to this extra framing, the door opening sagged in the middle about 1". I supported both the roof and this door opening while I framed, when I removed all the bracing after framing, the door opening now only sags about 1/4". It will sag more when I get all the siding and roofing installed, but I can live with the amount of deflection I am now seeing.



 

One negative of adding the framing is it bowed the 23-1/2ft door opening outward in the middle about 1/4". The roof rafter extra supports are pushing that part of the north wall out a bit. But, I guess I will still be able to get doors to function. I'd rather have this than the roof sagging 1"+.



 


 



Sod saw

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Is there any reason why the whole building can't be covered with a sheet of plastic or tarp to keep the rain off?  Just pull it off to the side while working on the structure.


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LT 40 hyd.          Solar Kiln.          Misc necessary toys.
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It's extremely easy to make things complicated, but very difficult to keep things simple.
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etd66ss

Quote from: Sod saw on June 27, 2022, 08:07:21 AM
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Is there any reason why the whole building can't be covered with a sheet of plastic or tarp to keep the rain off?  Just pull it off to the side while working on the structure.


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I probably should have covered it over the winter. Hope to have it done this summer so don't plan on buying any tarp.
I expected to get farther along on it last year than I did...

The non-kiln dried lumber I am using moved around a lot more than I thought it would.

etd66ss

Started on the siding:






 




I am wrapping the steel around the corners as I have no J-channel, F-channel, Z-channel etc:



 

It's annoying that this steel has a bunch of holes in it as well as tar all over it. Came off an old leaking roof.  Oh well, it was free. I'll try to use a heat gun to remove the tar, then quickly sand all the steel before priming & painting.  Lot of extra work but this saved me about $500 in plywood.

etd66ss

Metal siding and trimming out the door opening is done. Probably do the non-glazing portion of the roof next. Will have to buy plywood for that as I am all out of sawn stock and my sawmill is not up and running yet, still building the bed for it.



 


 


 


 

Even though I framed in for vents on the north wall, I ended up covering them with the metal siding to make the 23-1/2 ft span header as stiff as possible. Looks like I will be venting through the soffit.

The soffit is 12ft above grade. I'd like to use some kind of round vents that I can turn 180 degrees full open etc, via an extension tool from the ground. Anyone ever see any vents like that?

Something like this, but with a hex head in the center so I can reach up with a socket on a long tubular extension to rotate the vent.



 

Nebraska

How about big pvc ball valves hung upside down you could turn them with a forked metal piece ( street wrench)
like  you would use if they were an underground water shut off. Then you could vary the air flow if you want. Hose clamp  some screen over it to keep out the bugs...

etd66ss

Quote from: Nebraska on July 06, 2022, 09:56:47 PM
How about big pvc ball valves hung upside down you could turn them with a forked metal piece ( street wrench)
like  you would use if they were an underground water shut off. Then you could vary the air flow if you want. Hose clamp  some screen over it to keep out the bugs...
That's a good idea, thanks.

Edit:

Ok, the large PVC ball valves are crazy expensive.

YellowHammer

I have rectangular vents in my solar kiln, I open and close them with a stick.  Once they are right, they pretty much never have to be moved again, until the seasons change.  
YellowHammerisms:

Take steps to save steps.

If it won't roll, its not a log; it's still a tree.  Sawmills cut logs, not trees.

Kiln drying wood: When the cookies are burned, they're burned, and you can't fix them.

Sawing is fun for the first couple million boards.

Be smarter than the sawdust

etd66ss

Do I need to spray foam at all between the metal siding and the framing before I install fiberglass insulation or is that overkill?

doc henderson

I think you have to be careful not to trap the fiberglass between two "vapor barriers".  so, a vapor barrier on the inside and leave the fiber glass on the outside so it can breathe and not trap moisture.  
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

etd66ss

I am almost ready to install the glazing. Do I need to use the 1" bubble washers between the screws and the plastic? Lowes didn't have those, and I didn't order any as the instructions made it seem like they were optional.

etd66ss

Was off all last week, made some decent progress on the kiln:



 


 


 


 


Crusarius

I am a little late to this party. I usually watch for these builds to show up much closer.

For the roof glazing why not just overlap it like you would with shingles? 

etd66ss

Quote from: Crusarius on July 10, 2022, 08:09:43 PM
I am a little late to this party. I usually watch for these builds to show up much closer.

For the roof glazing why not just overlap it like you would with shingles?
I mulled that over, as well as butting them with H-channel. Decided to just go with 8ft of glazing. After I read the instructions for the twinwall, they don't recommend silicone for sealing due to movement via thermal expansion. I figured I would use the twinwall as per the instructions. I don't want to risk leaks. The kiln will dry about 1000 bd-ft less than the original design.

Another reason was the 24 ft long structure seemed unstable to me. Putting the plywood on the roof stiffened things quite a bit. I think it would have been too flimsy with a full glazed roof. I scaled up the VA tech design but still used 2x4 rafters and studs. I probably should have used 2x6's, at least for the rafters anyways.

Brad_bb

Is this the twin wall stuff you were talking about?  If so, when it says 49.5 inches, is that the vertical, and then the width is 99"?


 
Anything someone can design, I can sure figure out how to fix!
If I say it\\\\\\\'s going to take so long, multiply that by at least 3!

doc henderson

depends.   :) the width is across the channels and length is along the channel.  they are usually oriented top to bottom.
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

Brad_bb

Well I'm interested to see how the panels are installed.  I read the instructions:
https://www.greenhousemegastore.com/content/files/pdf/Multi_Install.pdf

I understand the point fastening, but am not clear about joining panels together, and how the panels join at the sides and bottoms of kiln so water doesn't get in.

@etd66ss are you using the 8mm twin wall panels?https://www.greenhousemegastore.com/coverings/plastic-sheets/polycarbonate-sheets/easy-ship-2-ft-wide-twinwall-polycarbonate?returnurl=%2fcoverings%2fplastic-sheets%2fpolycarbonate-sheets%2f
Anything someone can design, I can sure figure out how to fix!
If I say it\\\\\\\'s going to take so long, multiply that by at least 3!

etd66ss

Quote from: Brad_bb on July 17, 2022, 08:34:27 AM
Is this the twin wall stuff you were talking about?  If so, when it says 49.5 inches, is that the vertical, and then the width is 99"?



I bought the 6mm twinwall Polygal Tuftex from Lowes, it measures exactly 48 x 96. Which is kind of a pain, because I framed the roof 24" on centers. When using the H-profile to join, it ads 1/2". So I need to trim every panel along its length in order for the rafters to work out at the center of each H-profile. I didn't want to buy the glazing first because I wanted to see how the kiln build went before I spent that much money, but I should have. I would have framed the rafters differently so I didn't have to trim each peice.

etd66ss

Quote from: Brad_bb on July 17, 2022, 02:08:00 PM
Well I'm interested to see how the panels are installed.  I read the instructions:
https://www.greenhousemegastore.com/content/files/pdf/Multi_Install.pdf

I understand the point fastening, but am not clear about joining panels together, and how the panels join at the sides and bottoms of kiln so water doesn't get in.

@etd66ss are you using the 8mm twin wall panels?https://www.greenhousemegastore.com/coverings/plastic-sheets/polycarbonate-sheets/easy-ship-2-ft-wide-twinwall-polycarbonate?returnurl=%2fcoverings%2fplastic-sheets%2fpolycarbonate-sheets%2f
From everything I have read, you do not join at the ends, only sides, and the sides run down the roof, not across. If you need 16ft lengths for the roof for example, that's what you need to order. I decided against 12ft because it was $3000 for the glazing 12ft long due to shipping being outrageous. The 8ft long was $560 for 6 pieces at a local Lowes to get me my 24ft wide kiln glazing. I had to change my design on the fly but I wasn't going to spend $3000.

etd66ss

Cleaned all the roofing tar off the second hand steel, scuffed it up and cleaned with acetone. Filled all the old holes with pop rivets and got two coats of KILZ primer on the steel.






 


 


 

I don't think I want to paint the whole thing black.
   

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