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Author Topic: Solar Kiln Build  (Read 2237 times)

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Offline 78NHTFY

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Re: Solar Kiln Build
« Reply #20 on: February 24, 2017, 09:31:10 pm »
Have meant to build one for years but life's been getting in the way.  So, will live vicariously in the meantime through your build....
Here are a few pics of a kiln in Woodstock, VT, at the Billings Farm Museum, site of the first Tree Farm.  (Took the pics many years ago).  Hope the design is helpful.  All the best, Rob.
 

  

  

  

 
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Offline sawwood

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Re: Solar Kiln Build
« Reply #21 on: February 26, 2017, 09:36:32 pm »
We built a solar kiln with the plans from VT. For the collator we used plastic made for green houses. It last about 2 years and
then we have to replace it. Do you need the collator to be clear to let the sun shine in or could you just cover it to heat up the
inside. We have a lot of metal roofing that we could cover the kiln, planted black and put some on the under side of the rafters
planted black. Then use the fans to blow hot air down between then and then threw the stack of lumber? sure would save us
from having to replace the plastic every 2 years.

 Sawwood
 
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Offline Darrel

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Re: Solar Kiln Build
« Reply #22 on: February 26, 2017, 10:00:30 pm »
Sawwood, I don't know exactly what the numbers are, but somewhere I read what the difference was when just using black roofing for the heat collector. If my memory serves me correctly, if you did that, you would loose about 20% of your heating capacity. Maybe someone will reply with exact numbers. If I were you, I'd go to Home Depot and buy some of that corogated clear roofing, that's fiberglass reinforced. I've seen that stuff last 20+ years.
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Offline Deese

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Re: Solar Kiln Build
« Reply #23 on: May 11, 2017, 11:37:12 pm »
Update: I have decided against building the solar kiln...for now. Thanks to all who have reached out with advice.
Sawed 4 years with EZ Boardwalk Jr 13hp. 2004 LT40 Super 51HP, 1975 Case Tractor, Cooks Cat Claw Sharpener, Cooks Single Tooth Setter, Stihl MS 440, Stihl MS 250, 60" Logrite

Offline GeneWengert-WoodDoc

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Re: Solar Kiln Build
« Reply #24 on: May 13, 2017, 08:38:02 am »
The cover for a solar kiln was discussed in Sawmill & Woodlot magazine recently.  There is no question that two layers are essential.  Also, the further that the black absorber is away from the collector, the better. 

Glass is a perfect cover, but often is too breakable...hail, rocks, etc.  The stronger glass, like a patio door, is no longer as effective as a solar cover.  Glass with a seal between the two layers (thermo-pane) will get cloudy quickly due to kiln heat.  Glass that has a green edge is not so good.  Glass is heavy, so the frame must be stronger. 

Plastic film is ok if it is U-V stabilized.  Sometimes the material made off-shore says it is stabilized, but it is not really that good.  Plastic fIlm also gets brittle and then will tear, especially due to flexing from wind and fans. Five year maximum life, but often much shorter.   

Polycarbonate (single or double) is strong and durable, but somewhat expensive.  It is Very easy to install.  The two layer stuff seems to be close to perfect.

Corrugated fiberglass will last for 20 plus years and is low cost and durable.  It is not 100% clear, but other benefits make this covering very practical.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

Offline Delawhere Jack

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Re: Solar Kiln Build
« Reply #25 on: May 14, 2017, 08:35:51 am »
An FYI for anyone looking at corrugated poly-carbonate panels. HD and Lowes carry panels that appear to be identical, and (as of last fall), they were selling at the exact same price. The panels HD had were actually 40% thinner.....

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Offline Deese

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Re: Solar Kiln Build
« Reply #26 on: May 15, 2017, 12:01:12 am »
Good info Doc. See you Saturday.
Sawed 4 years with EZ Boardwalk Jr 13hp. 2004 LT40 Super 51HP, 1975 Case Tractor, Cooks Cat Claw Sharpener, Cooks Single Tooth Setter, Stihl MS 440, Stihl MS 250, 60" Logrite

Offline nativewolf

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Re: Solar Kiln Build
« Reply #27 on: May 15, 2017, 11:56:39 am »
The cover for a solar kiln was discussed in Sawmill & Woodlot magazine recently.  There is no question that two layers are essential.  Also, the further that the black absorber is away from the collector, the better. 

Glass is a perfect cover, but often is too breakable...hail, rocks, etc.  The stronger glass, like a patio door, is no longer as effective as a solar cover.  Glass with a seal between the two layers (thermo-pane) will get cloudy quickly due to kiln heat.  Glass that has a green edge is not so good.  Glass is heavy, so the frame must be stronger. 

Plastic film is ok if it is U-V stabilized.  Sometimes the material made off-shore says it is stabilized, but it is not really that good.  Plastic fIlm also gets brittle and then will tear, especially due to flexing from wind and fans. Five year maximum life, but often much shorter.   

Polycarbonate (single or double) is strong and durable, but somewhat expensive.  It is Very easy to install.  The two layer stuff seems to be close to perfect.

Corrugated fiberglass will last for 20 plus years and is low cost and durable.  It is not 100% clear, but other benefits make this covering very practical.

Might have something of value to add (doubtful but here goes).

In the greenhouse hobby world  a recent trend has been to use bubble wrap meant for pool covering.  It is UV stabilized, it has a great R factor compared to the other materials, cost per sq ft is very very low.  Now this is in the greenhouse world where they need to cover large areas.  However, it is holding up well, early adopters from a few years ago report no problems and it is dead simple to install.  Anyhow, something from another industry.  Hope it worthy of consideration

Offline WLC

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Re: Solar Kiln Build
« Reply #28 on: May 15, 2017, 11:19:14 pm »
Nativewolf, I had not heard of using the pool cover bubble wrap, but there is a product called solawrap which is made for the greenhouse industry that sounds very similar.  Supposed to be very durable with very good longevity.  Greenhouses in the UK have been covered with it for over 20 years with little to no degradation.  I've not priced it here in AK, although we do have a dealer for it in the state, I've thought it would make a good solar cover for a kiln.
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Offline nativewolf

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Re: Solar Kiln Build
« Reply #29 on: May 17, 2017, 07:16:44 am »
Interesting.  The thing with pool covers is that there are maybe a million pools, many have covers.  That means that industry has scale and prices are lower.

Just an fyi for you since R values might matter more in AK, folks are double layering it, then putting in blower fans to push an air blower between the layers (this is for the greenhouse world).  With the air layer R value goes up dramatically.  Pretty simple and very cost effective in greenhouses, maybe in your neck of the woods too?