Teakwood Solar Kiln

[YellowHammer]

KoolSeal is a reflective thermal barrier, so even without insulation, it would be a good way contain as much heat in the kiln as possible. 

I painted mine flat black, inside and out, floor to ceiling.  The black paint will turn the entire interior and exterior into a solar collector.  During the winter in the sun, my flat black exterior will be noticeably warm to the touch, transferring as much solar energy as possible to the structure.  For me, the solar kiln worked fine when there as a lot of sun, it was when there wasn't sun that I tried to optimize it.  It would be hard to paint the teak on the outside, it sure looks nice.

There is potential that that at some point you may get some standing water on the floor of the kiln, either from washing it, rain, or sometimes there is so much condensation that it puddles on the floor.  If you cut a small 1" drain hole or similar in a convenient place in the floor, and put in a plug, that's one less thing to worry about. 


    

[teakwood]

I will definitively not paint over the wood on the outside . Bought a 43 pint dehumidifier, the only "big" unit i could find, for 300$ . we are used to overpay for everything in CR. 

second coat is in and i still have half the paint left. still need to do the doors and the floor

electrical is done with 3 plug ins over the beam. i will put 4 fans in, i thought that more will be better

[teakwood]

teak what is your latitude?  what is your final angle on the roof?  just wondering

we are 11 degrees north. i did 20cm drop per meter of roof, that's about 11 degrees roofangle. you shouldn't go lesser than that, we have heavy rains in the rainseason and they need to flow away. roof angle will not matter alot, our sun here is alot stronger than where you guys live, a dry season day with sun form 6am to 6pm and 100 degrees you want to definitively avoid working in the sun, it's bad. probably need to vent the kiln so it won't melt away

[YellowHammer]

$300 isn't bad, and I used one during the winter months to boost drying.  I would take it out in the summer so it wouldn't get cooked and the solar is working full throttle.  

Airflow in a kiln can really help, as long as it's not enough to cause surface checking.  Generally the wetter the wood, the more effect fans have to the point where they can dry almost as fast on wet wood as a kiln, but as the wood dries out, the fans become less effective and that's where the heat from the kiln comes into play.

[teakwood]

not making much progress in the kiln because we had a dry weather window saturday and where able to get logs home, so back to sawing.
 
 
did a diffusor board on the upper edge of the kiln so the airflow increases 
 

[teakwood]

Making progress, dry season is here and i need this oven ASAP.

Mounts for the fans and the collector system


 


the "attic" where the fans should create a vacuum and push the hot air down 





Nice logs, they are getting bigger. This one was 37cm diam, 15"

the color is just awesome, and that's without the water trick

[Sod saw]

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I chose to paint the floor in our solar kiln white.  

The floor will not see the sun when the chambers are full because the wood casts a shadow and the wood is covered with light weight plywood (painted black) as a baffle and to keep the direct sun off of the top layer of wood.

When the kiln is empty, I did not want a black floor to cause the chambers to overheat without the mass of the drying lumber to soak up that potential excess heat.

I do enjoy working with teak, you are lucky to have an excess amount for your own personal projects.   Although, perhaps it is so common to you as pine is common to many of us; maybe you would enjoy something "different" for a change.


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[YellowHammer]

The best and easiest way to keep the kiln from overheating with an empty chamber is to prop open a door. 

[teakwood]

Man, it's a lot of work to do a proper solar kiln. thinking 2-3 days more and done

[tule peak timber]

Really nice looking! I did a teak job yesterday and was thinking of your operation.

[teakwood]

Where do you get your teakwood from and how much does it cost? what dimensions?

[tule peak timber]

I'm still working off of stock I have leftover from my dabbling in the teak business years ago. I haven't looked at the teak business lately, but did develop a business plan, which is now history. I hear that teak prices are sky high here in the States and my stockpile is steadily waning. !

[teakwood]

Do you have fotos from this left over teak? Where is it from? How old? Big or small growth rings? Interesting for me

[teakwood]

Almost done, tomorrow i start excavating where the kiln will be placed, need more space.

 
the two middle doors are heavy, need to put some handles on so they can be easier removed

got the electrical box installed 

 and did the baffle system, easy peasy 

 
the toys arrived

[teakwood]

Before and after, man did that gave some nice space, a lot more room now



it would have been better to open the quarry up here beside my house   was a pita to excavate





the kiln looks small now on the outside,  


everything done and loaded up with lumber and then rain 

[teakwood]

a question;  the first night it was 75 outside, inside the kiln 81. the DH sucked 2 gallons out at night, the fans are pushing hard. at the exhaust vents you could feel warmer air coming out. does the kiln work at night this way? it's so well isolated that the heat produced by the DH and the fan motors heat the kiln a little bit. should i buy a second DH? it would surely help

[doc henderson]

It (a second DH) would help most with capacity to remove moisture, and that becomes less important when the wood begins to get dry. Sounds like a great maiden voyage.  It would be interesting to know the RH in the kiln.  If it stays at 100% then your humidifier is at its capacity.  heat from the sun increases the internal temp and thus reduces the RH.  At night when the temp goes down the RH goes up.  Since your outside RH is so high, it is nice to have the DH to create dryer internal air.  If you vent too much, then outside air replaces the dryer dehumidified air and in effect, you are trying to reduce humidity in Costa Rica.   I think it would help to know the inside and outside RH, to know when venting is helpful vs spinning your wheels. In your area the DH makes sense.  

[Ianab]

The wood in the kiln would still be warm from the daytime cycle. Fair bit of thermal mass in there that's slowly losing heat to the air in the kiln.  Only concern I would have with adding more DH capacity is drying too fast. How your kiln operates in the tropics would be slightly different to the Nth American conditions so there is probably a bit of experimenting to find the optimal setup. 

[teakwood]

It (a second DH) would help most with capacity to remove moisture, and that becomes less important when the wood begins to get dry. Sounds like a great maiden voyage.  It would be interesting to know the RH in the kiln.  If it stays at 100% then your humidifier is at its capacity.  heat from the sun increases the internal temp and thus reduces the RH.  At night when the temp goes down the RH goes up.  Since your outside RH is so high, it is nice to have the DH to create dryer internal air.  If you vent too much, then outside air replaces the dryer dehumidified air and in effect, you are trying to reduce humidity in Costa Rica.   I think it would help to know the inside and outside RH, to know when venting is helpful vs spinning your wheels. In your area the DH makes sense.  

Ok, first some info. the lumber i put in was already airdried for one month and is at 22% moisture, so it's not wet anymore. put in about 2.5m3/1100bd ft. that's the kilns max capacity.
today we had sun from 12pm to 5pm, the kiln went to max 38C/ 100F, outside was 30C/ 86F.  outside humidity was 55-60% and inside the kiln 75%.
The DH showed 50% inside but that's just not possible, you can feel the warm wet air coming outside the vents.
The DH pushes about 14lt /3.5gal out in 24h
I think i need a good outside/inside thermometer with humidity readings and some cable sensors, does anybody have experience with a good product?


it's 7pm and the sun went down 2h ago and it's still 32.5C /90.5F inside, outside is 25C/ 77F

[doc henderson]

Not sure I would call them "great" but "good", is the accurite with a remote to put in the kiln, and a base that measure inside your shop or outside depending on where you put is.  I get them on amazon and they used to be 14 bucks.



 

this one is in the shop and the remote is 100 feet away in my metal container with a DH unit.  I turn it on once a month or so to reduce the humidity for my stored lumber in there.  I monitor the temp and humidity from inside the shop to know when to go turn on the fans and DH.






this is an outside stack that I dried down to 8% under clear plastic.