Teakwood Solar Kiln

[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, lol 


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.

[teakwood]

thanks doc for all the help.
but dang!! you even have the neater stacks than me!

[doc henderson]

well, I am older and more experienced, but I still do not have teak!  

I have a thread on how I stack sticker individual logs.  what you are doing with pallets will work best for you.

[teakwood]

i made about 40 pallets by now and will run out of free ones in 2 weeks. we finally do have some stock in the storage, but i want more! have 800 deck boards stickered now, the goal is 2000, and have them dried (15% is fine) so when a bigger order of 500 boards come in i just tell the costumer: come pick up the planed and grooved boards in 2 days  ;D ;D

[doc henderson]

except for the 4 x 4s those are single wide stacks from one log each bundle.  your operation has grown leaps and bounds.  Very good.


https://forestryforum.com/board/index.php?topic=105726.msg1646583#msg1646583

[doc henderson]

your stacks are very neat.  the accurite in the picture is 30 bucks on amazon.  it has back lighting for in the dark, and has a high and low reading for 24 hours.  I would put the remote in the kiln, and the base in the open shop area.

[YellowHammer]

It's unusual to have only 1 sticker per 4 feet.  Most times that will induce a sag between stickers when heated in a kiln.  I've never dried teak so don't know how it behaves.  

[teakwood]

I know Robert, but i have never had any problems stickering like this. Will see if the kiln makes any difference because of this stickering space. I don't think so, 70% of the drying happens in the 1-2 month of airdrying prior to the kiln drying.

[beenthere]

However most wood shrinkage happens below fsp (fiber saturation point) so the outcome of the kiln drying should answer the question. Teak may be different here. Great to follow along. 

[teakwood]

Wow, this kiln is just astonishing me in any ways, never expected such results. at 2pm the kiln goes to 45C/113F
last night at 8pm it was 38C /100F

 

and today at 5.30am 34C /93F incredible the heat it maintains over the night  

since 4 days the kiln is loaded and the 1" boards went from 22% to 16%, i'm just amazed.
Put in another DH yesterday and the 4th fan that was still missing, now the built is complete and i spent 2200$ on it and a ton of working hours. but dang this kiln will pay for itself in 2 month. thank you all for the incredible help and wisdom , it's a full success. i'm so happy!

[doc henderson]

It would be interesting to compare inside and outside RH.

[teakwood]

outside at day 55-65% inside 45-70% i don't get that, of course it's very hot inside so the air can take more moisture, but when i stick my arm inside the vent window i can feel the moisture.

I measured with the 25$ wind speed gadget i bought, so not very confident in the readings.

Will buy a thermometer as suggested

[caveman]

I know our wood is getting close to dry when the RH inside gets low.  I'm glad your kiln is working well.  I had no doubt. Our kiln is the only thing that makes us money without a lot of labor involved. 

I thought about you today when I saw an oak tree that was painted white for the first several feet above the ground.  I noticed that that was a common practice in CR.  What is the purpose for that?

[doc henderson]

I think that means your kiln is working and pulling water from the wood.  the RH will fluctuate a lot.  remember it is relative to the temp.  so at 20° warmer inside the kiln, the RH may be the same inside and outside, but there is more water in the air inside the kiln.  so then some venting will take out the moisture laden air and replace it with dryer air.  the fresh air from outside may have the same RH going in, but after warming 20° in the kiln the RH drops and stats picking up the moisture from the wood.  You are using the sun and mechanical for heat.  you can vent and loose heat, or use the DH.  If you keep records, you can see what works best and then try to replicate that in your kiln despite changes in the weather.  the RH is the water in the air based on the temperature and how much water could be held all the way to 100%.  as the temp goes up the water amount that can be held goes up, so the saturation % of that air goes down.  RH.

[teakwood]

I thought about you today when I saw an oak tree that was painted white for the first several feet above the ground.  I noticed that that was a common practice in CR.  What is the purpose for that?

We (foreigners) don't get that either. they say it looks nice, think that's the only reason. but this practice is getting less common every year.

I think i will unload the 1" boards from the kiln in 2 days and put another load in. so mi question is: do i need to cool down the wood for a day before i put it on the outside?

that's the load now, a stack of 1" and a stack of 3"

[teakwood]

the RH will fluctuate a lot.  remember it is relative to the temp.  so at 20° warmer inside the kiln, the RH may be the same inside and outside, but there is more water in the air inside the kiln.

Thanks Doc, that confirms my theory. i have RH readings in the kiln from 45% to 75% and was confused.