Solar Kiln Build #2

pineywoods · June 01, 2011, 09:33:03 AM

Fil-Dill, check with radio shack for a thermometer. They have one with digital readout and 2 probes. Put one probe up in the top, the other where air exits the stack. The difference in the two is a very good indication of how much moisture is being pulled from the lumber. Makes a fairly good moisture meter that measures the whole stack rather than just 1 or 2 boards.

Bill Gaiche · June 03, 2011, 05:23:29 PM

Was able to load 380 bf of red oak into kiln on 6-1-2011. Mostly 8' and a little 6' lumber. Would have held more but I didnt take enough to fill it up. I kinda underestemated how much it would hold by the eyeballing method. Thats ok because that is enough for my next three projects. this fall. The best I can figure the Kiln cost me $1050.00 to build. Had my own lumber for the framing except the treated plywood. Biggest cost was $225 for plywood, $240 for sheating and sheating strips and $103 for the fans. The rest of the cost was in the insulation, plastic, hinges, inside coating, outside paint, timmer, wire, caulking, nails,vents and timmer. bg

Larry · June 03, 2011, 05:48:22 PM

I like the color...sorta reminds me of this one.

At 16% MC you will have to nearly close or close the vents to get any additional drying. In this weather you should be done in no more than a couple of weeks. The last 2 or 3% is the very hardest to get out.

Bill Gaiche · June 03, 2011, 08:50:15 PM

Yeah Larry, they could be related for all we know. Thanks for the info on closing the vents. I had no idea that it would only take a couple of weeks to dry. I will check it next wendnesday for mc and close down the vents and check it again the next week. bg

Coon · June 04, 2011, 02:56:06 PM

Nice jobs on the kilns guys. Someday I will be building my own to dry 16' lumber and it will be situated completely away from the grid. I will need to run a solar panel and batteries to keep the fans going. Got to many other things on the go right now though. Please keep us informed on how well they work and things that if you had to do it over again what you would change.

Bill Gaiche · June 04, 2011, 03:09:01 PM

Coon, thanks. Hope you can get one built soon also. Will give you an update as time goes along. bg

Norm · June 05, 2011, 07:37:44 AM

Very nice work, thanks for showing us.

Magicman · June 05, 2011, 08:39:27 AM

bg, You not only built a worthwhile project, you did a very good job of illustrating the build. Thanks.

tim1234 · June 05, 2011, 09:41:38 AM

Showing my total ignorance....where does the moisture go in a solar kiln? The sun heats the air, but how do you keep the humidity low?

Tim

pineywoods · June 05, 2011, 01:43:46 PM

Quote from: tim1234 on June 05, 2011, 09:41:38 AM
Showing my total ignorance....where does the moisture go in a solar kiln? The sun heats the air, but how do you keep the humidity low?

Tim

Tim, that shows you are thinking,,,good... Conventional solar kiln thinking is---when the air inside gets so humid no further drying takes place, the humid air is dumped outside through a vent, and replaced with fresh air. If you live in the deep south, that fresh air will already be rather humid. As a result, it's difficult to get lumber much drier than you would get with plain air drying. BUT the kiln will be somewhat faster. Easy fix-- stick a small cheap room de-humidifier inside the kiln and just run it at night. No venting needed.

Bill Gaiche · June 05, 2011, 01:59:33 PM

pineywoods, was wondering, when you close off all the vents and the temp rises inside does the extra heat cook off more of the moisture in the kiln? Wouldnt this wood get drier versus air drying at the same location? bg

pineywoods · June 05, 2011, 02:37:01 PM

Bill, there all manner of theories and experts on the subject. I'm no expert, but I can tell you from experience with 2 kilns that it is difficult to dry below 12%. I can do that well with air dry, just takes a lot longer. With the de-humidifier and no vents, we dry oak and cypress down to 6%.

Buck · June 05, 2011, 04:58:40 PM

Bill and Piney...thanks for the posts

Bill Gaiche · June 05, 2011, 09:05:52 PM

pineywoods I will see what this load does and if needed I will add a de-humidifier. bg

WDH · June 05, 2011, 09:07:57 PM

Piney,

Does dehumidification at night thwart the conditioning cycle? Has you experience with oak been good?

pineywoods · June 05, 2011, 09:28:17 PM

Quote from: WDH on June 05, 2011, 09:07:57 PM
Piney,

Does dehumidification at night thwart the conditioning cycle? Has you experience with oak been good?

I don't think so, it seems to help.More trade-offs. A dh unit will make a fair amount of heat, enough to make a difference in how much the interior cools off at night. In my opinion, the only reason for high heat is to kill bugs and cook their eggs. So far, my experience with oak has been good, now watch the next batch get destroyed ;D

Bill Gaiche · June 05, 2011, 09:44:32 PM

pineywoods, what size dh are you using?
Larry, are you using a dh. if not what mc are you getting your red oak to/ bg

pineywoods · June 05, 2011, 09:59:51 PM

Quote from: Bill Gaiche on June 05, 2011, 09:44:32 PM
pineywoods, what size dh are you using?
Larry, are you using a dh. if not what mc are you getting your red oak to/ bg

Don't rightly know. Just the cheapest thing I could find :

Actually, it's a sears unit, specs say enough for 1 room only.

Larry · June 05, 2011, 10:19:50 PM

Right now I don't have a kiln (a Nyle under construction). Left the solar one on the farm when I sold it and kcwoodbutcher bought my Ebac DH.

When I was running my solar kiln I could hit 6% but it took too long. I would stop when my sample boards hit 8%. There would be a few boards in the load that measured lower and a few that measured higher but nothing over 10%. And I should add that my solar kiln was completely solar except for the fan motors. Think I mentioned before the last two or three percent are always the hardest to get out. At least in my kiln I had to keep the vents just barely cracked. I helped build 3 other kilns similar to my kiln and each one performed a bit different because of different construction features or insulation.

I did dry with a room dehumidifier for a while to increase my production. The kiln was styrofoam sheets duck taped together inside the shop. It was a jury rigged deal but really air tight. I ran that dehumidifier wide open with oak and never got any case hardening at all. I don't think the small dehumidifiers have a big nuff compressor to do any damage. Of course it would be prudent to watch any new kiln closely through the first couple of cycles.

Bill Gaiche · June 05, 2011, 10:32:51 PM

Thanks guys. bg

Bill Gaiche · June 05, 2011, 10:36:35 PM

have you guys ever dried any 4x4 red oak in your kilns? I would like to have some to build some legs out of. bg

WDH · June 06, 2011, 07:21:22 AM

Tell me about how water acts in the kiln. Is there condensation that runs down the inside of the collector panels? If so, how do you design to get rid of this water? Is there any free water in the kiln otherwise that pools up or gets things soaked?

Larry · June 06, 2011, 08:28:42 AM

Depends on how it is built. My kiln had R-20+ foam walls and double pane roof. All the moisture exited through the vents. On one of the kilns I helped build, the owner used R-13 bats and a single pane roof. It worked well during the summer but during winter moisture would condense on the roof during the night. In the morning there would be ice sickles hanging from the roof rafters. Not good.

Den Socling · June 06, 2011, 10:39:22 AM

A 4x4 red oak square is a much different animal than 4/4 lumber. You would spend a long time and I believe you would be disappointed in the end. Better to laminate those legs.

Bill Gaiche · June 14, 2011, 10:24:13 PM

Today I pulled the red oak that I had loaded two weeks ago. The MC was 6%. I was really suprise that it had dried that fast. Ran it through the bandsaw to get a straight edge on one side. Wood looked good as far as I could tell. It made me feel good that I was able to do this. I loaded back the rest or the red oak that I have sawn with some cypress on the bottom. Now I will be able to start on those projects I have in mind. Thanks to those who have guided me in the Kiln build. It made a lot of difference. bg