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Newbie Solar Kiln Quesions

Started by Shaggy, December 24, 2014, 09:11:03 PM

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Shaggy

First off, Merry Christmas ya'll.... :snowball:
Now on to the questions
1) I live in south mississippi and all the picture of solar kilns I see have the clear panels at about 22-30 degree angle but here all but winter the sun is alot higher than up north so do I need to make my kiln more flat, like at 15 degrees instead of 30?
2) I need more info on construction as I thought the sun was just on the wood but after looking at the post of all the pictures of solar kilns they all had black plywood or other things under the poly-carb panels. I have a greenhouse I thought could be used as a kiln.
3) how would I convert the greenhouse into a kiln? or would it be better to build a purposely built kiln?
4) In Mississippi it is ALWAYS humid, what is best way to dry ? Is there a cheap dehumidifier I could buy?
5) What is the cheapest way to check moisture content in the lumber?
6) I am also looking at drying some wood that is said to be really bad about warping while drying so can I semi-dry it and then put the cant back on the mill and cut thin boards ? What % is best before its too dry and won't cut well on mill?

Glenn1

Vacutherm IDry, Nyle 53 Kiln, New Holland Skid Steer, Kaufman Gooseneck Trailer, Whitney 32A Planer

jimF

replying to #6: don't plan on resawing a cant.  The drying stresses may cause the resulting boards to be cupped.

Seaman

One of these smart fellas will post the link to Pineywoods kiln here on FF.
FRank
Lucas dedicated slabber
Woodmizer LT40HD
John Deere 5310 W/ FEL
Semper Fi

GeneWengert-WoodDoc

If you look at the Virginia Tech kiln, developed in 1978 and now with over 900 units and even a class offered annually, the write up includes information on the construction features.  Likewise, there was an article in Feb 2008 Sawmill & Woodlot magazine about solar designs (and they do have back copies available).

Here are short answers to your questions.

1) The angle should be at your latitude, perhaps 32 degrees where you are located, but go for 30 degrees.  For better wintertime performance, but lower summertimes performance, raise the roof by 10 degrees.

2) The construction details are in an article entitled "Design and Operation of a Solar-Heated Dry Kiln" at
https://pubs.ext.vt.edu/420/420-030/420-030_pdf.pdf

3) A greenhouse does not use energy for drying, so the energy requirements are about half of what a kiln uses.  Temperatures are usually only 100 F maximum.  Hence, the greenhouse is not what you need.  A solar kiln will be insulated to conserve what solar energy does come into the kiln.

4) It might surprise you to know that oftentimes the humidity in WI is higher than in MS, except close to the coast.  But, if you heat foggy air (100% RH) by 25 degrees F, you will have around 30% RH.  So, that is why we only run the fans when the sunny is shining and the RH in the kiln has dropped.

5) Incorrect MC can ruin a project or make a customer unhappy.  So, get a good ($200) moisture meter from a U.S. manufacturer.

6) Cut the lumber to the desired thickness when green and then stack it correctly (16" sticker spacing, perfect sticker alignment,  top weights, etc.).  If wood has so much stress that it still warps, you would have had trouble resawing it as well...the stress is in the tree and not put in by drying.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

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