Solar kiln floor insulation??? Edit… my solar kiln project

[Nebraska]

 9 inch 12 volt dc radiator fans probably for some kids rice rocket car project. Supposedly 650 cfm.  80 watts power required. 

[Nebraska]

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Made some progress yesterday afternoon going to add some metal hangers to the rafters and some blocking, then build the header for the door opening and the fan / tarp baffle header.  

[Nebraska]

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Got most of the plywood sheeting on the kiln. I am using 19"x 8 ft manufacturing waste I need about six more sheets to finish the non collector side of the roof and the top part of the far side. Had a nice sunset too. 

[Nebraska]

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Back roof sheeted and synthetic felt on. 

[Nebraska]

If things align today I will put the twin wall polycarbonate sheets on the collector that will be the outer glazing.  I am pondering door design. 

Do I want a door that opens up with a boat winch lift or something similar??

Two doors that open to the side with +\-a removable center post? 

Or a drop down door? 
I was leaning towards the first option but 
wondering what the brain trust thinks. 

[doc henderson]

My friend and tree service guy did one on the glaze side and the whole front hinges up with a cable and it works well.  I will add, this is not how I would have done it.  he had an existing building that he adapted, so the glaze wall was all he added.  He did not insulate much, and it was way hotter in there than outside.  He kept is light with a frame and plastic glaze.  Like Gene Wengert once told me as I overthought every aspect, "it is only a solar kiln" Dr. Gene Wengert.   

[doc henderson]

I texted my buddy, Sean.  He says it is two sections, and he can lift it by hand.  It is easier with two.



It hinges at the top.  He is the one who milled up the burl for me with his wide mill.  He is also the one who make the family table from Homey locust with all the great color..

[Nebraska]

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Glazing is  on and we had a very pretty sunset. Pretty good day overall. 

[Larry]

Do I want a door that opens up with a boat winch lift or something similar??
Two doors that open to the side with +\-a removable center post?

I hinged the entire roof. To lift I had a removable center post with a hand crank on it. Easy to load with a machine or by hand.

More pics in my gallery in the kiln section if your interested.

I built this in pre-historic times at my farm in north Missouri. It went with the farm when I sold out.

[Nebraska]

I thought about that design Larry but since I was doing this on a whim with pallets the front wall was taller and I just did it. I don't know what will become of this but I am really contemplating building two more smaller kilns to use for drying thicker wider  slabs. I have a friend who is a cabinet maker and has demand for custom tables and bar/counter tops.
 One kiln a little over 12ft and one maybe 9 ft  both front load with a lift up door. I have had enough requests to know I could do some drying for dollars. Seems more flexible schedule wise. Which would be good  for me right now. 

[Nebraska]

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Got the plywood attached fully with stainless steel staples and about 2/3 of the felt. Ran out of cap nails, T50 staples and daylight. 

[Nebraska]

Just charting some progress. 
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[Nebraska]

So the next step is to finish the felt and then design and install a door. I am still leaning on an upward opening door thinking that gravity would help it seal. 

Does anyone have strong opinions on door designs?  

Side opening will eventually sag and get tougher to close , but probably more easily built.  If I built a ramp style door I'm afraid it would be much heavier do to using it as a ramp when loading and unloading the kiln. Also tougher to seal. 

[doc henderson]

Hey doc.  Bostitch and prob. other makes a stapler the feeds the plastic caps along with staples.  Handy if you had much more to do.

[Nebraska]

Yeah I have the staples and caps in the basement my carpenter friend has the gun. I just didn't take the time to run over and borrow it from Rick. They do beat the hand nail variety. Actually using an 18 gauge stapler and caps by hand w/o auto feed isn't bad unless you need the other hand for hanging on.   I was also not motivated enough to drag the cords and the air compressor over there  its far enough away from power, it  was an extra step. 

[YellowHammer]

I built conventional side opening doors, leaks are not a problem with a solar kiln, I put my vents in the doors themselves.  I just beefed up the hinges and framing and built them stout but not overly heavy and gave the threshold a little ramp to align and allow them to be pushed into place if they sagged a little.

 

[Nebraska]

Thank you, so I don't have to worry too much about perfect air tight seals. I doodled out an overhead door plan yesterday. My brain was trying to remember circle and triangle geometry concepts so that the leading edge of the bottom of the door frame would clear the front as it swung. That stuff is a lot rusty. 

[YellowHammer]

No, not with a solar kiln. I had vents over the doors and vents on the doors themselves.  Since moisture is removed from the solar kiln via air flow, during a normal drying cycle the vents are open to some degree to let the moist air out.  The only issue would be sterilization, but that takes overpowering heat in a solar kiln, so it's a whole different ball game.

Typically, once I got my vents set correctly, I almost never had to fool with them, except for a change in season.  Pretty much a set it and forget it Easy Bake oven. 

[Tom K]

Thanks for the conversation guys. I'm at a similar point in my build, so it's helpful. 

I opted for a more traditional VT design adjusted slightly for length, with the double doors on the high side.

I like seeing your progress pictures.

[Nebraska]

Well I hope my heating for sterilization idea works but I won't have pictures until I get the inside lined. Lord only knows when I will get there.  It won't be solar.....

[doc henderson]

you can triangulate with a cable in line with the pivot of the hinge and the middle outside edge of the doors but above the hinge on the outer ends of the doors.  with a turnbuckle they can be adjusted over time.

[teakwood]

Just charting some progress.
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i didn't go thru the whole post, just kinda overlooked the pics, so excuse me if i missed something, but are those two tiny fans the only ones you install?? needs way more fans, more airflow means faster drying. i have four 170W fans (normal metal house fans, 50$ each) and they make alot of wind. bought 4 extra ones when i built the kiln for replacement because they are not industial quality. after 2 years of use they still sit in the storage room and the original ones are still going strong!

[Nebraska]

Yes they are 12  volt radiator fans that are rated at 650cfm. I just figured that they would handle the heat easily and I was going to play with some solar panels so suns up they come on sun down they rest. 
@tule peak timber 

I just wasn't sure where to start. 

[Nebraska]

I roughed out the interior volume to be about 650 cubic feet so the fans at peak should turn the air over 2x per minute roughly. 

[tule peak timber]

Yes they are 12  volt radiator fans that are rated at 650cfm. I just figured that they would handle the heat easily and I was going to play with some solar panels so suns up they come on sun down they rest.
@tule peak timber

I just wasn't sure where to start.

These are the fans that have been running since last fall. So far so good.