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eddiemac
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Solar Kiln

Well, I've finally begun work on a solar lumber drying kiln using the Virginia Tech plan.  I feel pretty silly using lumberyard wood, but want to get it up as soon as possible, not spend ages messing around with oak in the hot sun.  I envy you guys who live near (or in) softwood forests.  The best we have around here is red cedar and I'd feel guilty using it for framing lumber (although I've cut it for people using it that way; walnut too).  Here are my beginning photos.  More to come:

Dewchie
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Looking good Eddiemac! I see your sitting on posts buried into the ground. Do you have clay soil, sand etc? Looks like cedar? Thaks for the pics

Cheers!

Steve

eddiemac
eddiemac's picture

Hi Dewchie.  We have clay soil that hits a hardpan around 30 inches.  That's where I stopped digging.  Those posts are recycled creosoted electric poles.  It rained on everything last night but I got the roof panels on today, just in time for a massive thunderstorm that brought tornadoes to Oklahoma, Kansas, and Missouri. 

Dewchie
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Eddiemac, It, sad to here about the tornado's on the news. Hope all is well. Our prayers go out to those affected.

I also have clay with hardpan the same distance down. However I have to dig down 48" and install bigfoot sonotubes to prevent heaving from the winters we get. Wish I could get some helical post would be easier. Looking forward to see more pics.

Cheers!

 

Bill
Bill's picture

Good going Eddie glad to see some one has got a lot further than  me I'm still in the going to do it one day after many yrs. thinking about it. Maybe your project will inspire me . TY for posting.

Bill

eddiemac
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I suggest mild weather, maybe in the fall when it gets cooler.  I've been baking out there.  I wanted to coat the inside walls black before I put on the roof, but rainy weather intervened.  I'm dreading the inside work with the roof on.  Oh well, onward.

 

r.garrison1
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When you are working on the inside, maybe set up a sprinkler on the roof, to keep things cooler?

smithbr
smithbr's picture

Eddie

You might have to work on the interior at night.

Funny, I'll be out in the back again building ours today.  Seem to have chosen another week of rain for vacation.  Oh well, less temptation to go messing around in the canoe.   I'll have to go find that posting on how to attach pictures.

What are you using for the rear door - I've got a donated 9x7 insulated garage door that I'll use 3/4s of.  Of course, that's caused some changes to th Virginia Tech plan, but that's okay.  Our front is 5'x10' of glass, all one sheet - we got the big picture window thermopane apart without incident - but nearly!  Man, that joint is tough.

We're debating setting a door into the end, but I think opening the garage door will be reasonable.  Might compromise with a plug door, not a hinged one.

Had bought a bag of 6" insulation in the shed, for the floor.  Got home yesterday, the bag was out in the field behind the shed.  Looks like a bruin decided it must be edible.   Took three or four bites, and one swipe down the edge of the bag - probably what launched it into the field.  That'll be one strange pile of dung for some tracker to figure out!  the whole bag smells like burnt sugar, no wonder bear was interested.  Hope the smell subsides, wouldn't want him opening up the kiln for a look-see.

Blair

eddiemac
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Thanks for the good suggestions guys.  It looks like we're going to have three days of mild weather, so I guess I'll get the inside of the kiln coated black tomorrow.  I did the interior sheathing and the ridge cap today.  Will post pics soon.  I am following the Virginia Tech plan almost verbatim, so the north doors swing from both sides and meet in the middle  -  a 12" 4" opening.  I haven't built the doors yet.  We've never seen any bears around here, though black bears can be found in southern Missouri I think.

Dewchie, 18 inches is as far as we need to go here to get below the frost line, and with the milder winters we've been having, it may soon be 12".

r.garrison1
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I had some gate posts set; where I am in Eastern Oregon (Wallowas), it's about 3' for the frost line. They had a post pounder; I didn't get to see it in operation, but apparently, it drives an 8' diameter post whereever you want. Here, there is a lot of broken granite in the soil (loose stuff, no clay). The guy told me that they could either drive through or push the rocks out of the way when they drove the posts. Sure would beat digging down through the stuff.

Dewchie
Dewchie's picture

The problem with just post in clay and alot of water saturation, when frost sets in it can heave a post up a foot. This has happened to me when I sunk a 4x4 in 40" in two years it lifted at least a foot and I can't bang it back down. Though if I would have put a cross member at the bottom it would have helped. I used a bigfoot and 8" sonotubes filled with concrete in clay and never had a problem (except the digging). I was looking at helical posts which is a good way except I like doing things myself and I can't seem to find where I could get some. 

eddiemac
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Here's some more pics:

I'm using four 8" duct fans for ventilation.  The doors, vent covers, exterior paint, and a little bit of siding are all that's left to do of the building.  Then I'll have to run an electric line, paint some old tin black for a collector plate, and hang a black tarp for a baffle.

Bill
Bill's picture

Eddie it's LOOKING real Good !!!

Bill

Dewchie
Dewchie's picture

Nice pics,Where do you get the fans Eddiemac?

Steve

eddiemac
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Thanks Bill, Dewchie.  The fans were an ebay purchase, Aero Flo 420 CFMs Inline Duct Air Booster Fan @ $34 each. 

Dewchie
Dewchie's picture

Thanks Eddiemac, one day I would like to build one also so this thread will come in very handy.

Cheers!

Steve

Bill
Bill's picture

TY for the tip that's a very good price for toughs fans, are you going to control them with a thermostat ? Next pic. we see will be the lumber drying smiley.

Bill

eddiemac
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I haven't decided how to control the fans (which will be turned off at night).  I may start with just an on/off switch in my shop and remember to turn them on in the morning and off at night.  If that proves to be troublesome, I'll look for other solutions  -   haven't really got it all thought out yet.  The fans are supposed to be good to 266 degrees.  The next pic is liable to be of a completed north side with doors and bottom vents.  Be patient   -   I'm going to dig a shallow trench from my shop to the kiln (for electricity) with a mattock, may take me awhile.

smithbr
smithbr's picture

Hi folks

Has anyone considered using solar power for circulation fans and venting?  It would seem a natural match, since if the sun is out we've got heat production.  I'm interested if anyone has done this, if not I'll look at it.

 

Blair

Post Oakie
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Solar is running at about $4 per watt.  That's about $3k per horsepower (750 watts).   The system also needs an inverter.  You could string a lot of wire and buy a lot of electricity for that.  It might be practical in some remote locations, though.

smithbr
smithbr's picture

Yes, if I were powering 115VAC fans.  What I had in mind were recycled 12VDC computer fans, a couple of battery charging panels, and a surplus battery.  Rather than putting the fans at the peak of the building, where the heat is worst, I'd put them at the bottom of the side panels for venting, and at the base of the thermal column for air heating.

I've got to put in an AC run to the sheds anyway, but I thought I'd try the solar idea out because I've got the panels, the DC fans, and the battery.  All I need are a couple of thermostats and maybe some form of solar cell to switch it off at night to preserve the battery.  I might try running the fans directly from the cells, if the current output is close enough to the fan maximum; that way, they'll turn if the sun is generating, and not if not, which is pretty much what I want anyway.  I'm sure I've got lots to learn here, but trying things is fun too.  Even if I need to do some AC assist, if there's benefit from using the castoff 12V stuff I may still use it.

I may also try using some of the temperature-driven greenhouse vent arms to open louvers for venting, but that's problematic as depending on the MC, I may want to retain as much heat as possible at times.

Thanks

Blair

eddiemac
eddiemac's picture

smithbr, check out:  http://www.solarkilninfo.com

Post Oakie
Post Oakie's picture

Great find.  Thanks for posting the link.  A solar kiln has been on my "short list" for years!

citrafarm
citrafarm's picture

The best solution for controlling the fans is a cheap on / off timer like you use in your house for controlling lights while on vacation, can buy at any hardware or Wal Mart. Set it for about 1 hour after sunset to shut fans off and come back on about 1 hour after sunrise. This allows fans to move the heat out and humidity to come back at night to condition or relax the wood and come back on when the sun is high enough to provide heat. no need for thermostat on solar kiln. Good move on the metal fans, left mine shut up with no wood in it and sun shining in, fans off and it melted the plastic blades. I also put a roll up tarp in front of the clear panels so I could roll it down and shut kiln down completely when not in use. Bought a silver front / black back tarp for both my baffle and the front roll up. Front roll up tarp faced silver out to deflect the sun when not in use, black forward on baffle to absorb heat when in use.

eddiemac
eddiemac's picture

citrafarm, thanks.  It's so much easier to find out from someone who knows than knocking about in expensive experiments oneself.  I'm assuming the silver roll-up tarp "in front" of the clear panels is on the inside of the kiln, not outside?

citrafarm
citrafarm's picture

Correct, the inside, I rolled it up on a piece aluminum conduit and held up with straps mounted to the top. You know the kiln is a great hot house during the winter for growing vegetables and such. Use the front tarp to control the amount of heat and sun. I would have suggested painting the interior wood black before constructing it and then just some touch up to finish but it was to late when I saw you pictures.

eddiemac
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citrafarm, the front tarp seems like a very good idea.  Where can I get a tarp with a black side?  Suggestions are welcome, from all.   

citrafarm
citrafarm's picture

I buy mine at Northern Tools and Equipment, go to web site below and type in tarps. You will see silver front black back type tarps. I buy a very large and fold it over so it is black on both sides for the baffle. This allows you to put a piece of conduit in the fold for weight to hold it down on your stack of wood and roll it up based on how tall your stack is.     http://www.northerntool.com

eddiemac
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Thanks!

eddiemac
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Getting to the home stretch now.  I've got my electric line in, a timer hooked up, and doors on.  Got some painting to do, vent covers, hang a black tarp, and cut some old tin for the collector plate.

Bill
Bill's picture

Looks real good Eddie nice job !!!

Bill

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