Building a Kiln

We have wood plantations (like 350 hectares of them) and we process wood. I have one kiln for a furniture factory, but it runs on electric. What I would love to do is use a building we have, made of concrete, for a kiln. It would be very easy to have it process 3 lots of 4,000 BF, which is perfect, for now, for us.

Obviously, using scrap lumber appeals to me instead of electricity.

A little of background. We are in the tropics, during the rainy season, solar is not reliable enough, but it could be used for supplemental the rest of the time. We can build just about anything having built all our buildings ourselves.

One thing on the design of a kiln. Tropical woods aren't very picky. You don't want to get too hot (like not over 120 F), so a rise in temperature of 40F is all you need, less than that is fine. Slow changes in temperature is the best to prevent splitting of wood, and it is excellent to cool down a bit over night, to let the wood "relax". It takes longer, but produces a better quality result.

So, rocket stove with huge mass? Load it up twice a day or so, etc?

Actually a rocket stove with no mass and the exhaust running down the length of the building with a little rise and a chimney over the ridge line. the humidity in the building as the wood dries will be thermal mass enough. A well built and sealed stove should kick out more than enough heat to dry the wood to around 10%. As a boat builder I like 15% but I think folks ship way lower for standard KD.

Ernie Wisner wrote:Actually a rocket stove with no mass and the exhaust running down the length of the building with a little rise and a chimney over the ridge line. the humidity in the building as the wood dries will be thermal mass enough. A well built and sealed stove should kick out more than enough heat to dry the wood to around 10%. As a boat builder I like 15% but I think folks ship way lower for standard KD.

Not sure, one of the biggest dangers in drying wood is too much heat. You want gentle heat and what appeals to me about a large cob thermal mass is that it takes a while to build up heat, and takes a while to cool down too. This should result in a better quality product.

Usually, we dry to between 8 to 10 percent, but that is because sometimes the wood is used where there is air conditioning. I can see 15% for boat building though.

By the way, I did buy and download your book sometime ago - and enjoyed reading it.

Thanks Fred
Adding mass would be great for the kiln just get the heat distributed in the space. The guy You ought to be talking to is Jay Nydek. however; i dont think he has internet on his mountain. He uses a rocket kiln for drying wood.
So i am going from memory of what we discussed about his kiln building. He heats somewhat fast in the Yukon I think. mostly due to the wood dropping temp so fast and needing to heat the mass. I do know that he has no cob on his stove. 4 to 6 inches should do you for slow heating. I would put another inch or so of good plaster to ensure i was not going to degrade my cob to fast.

Either way the heat of the stove is far less raw that a box stove. I would say test it. you can lay out and test the stove make a hoop house and test how fast the heat comes up and how quick the drying happens. its gonna happen faster than in the big kiln but should give you a fair idea.

Sounds like a good plan.... now maybe I could tempt you into visiting us, you get here, I will put you up... You know I have 350 hectares of reforestation and have my own furniture / millworks? Surely that is Nirvana for a boat builder. lol

One thing I have wondered about, getting really efficient here, is a combination of gasification and kiln. A lot of our lands are off the grid, and if I can combine a system that will generate electricity for processing with a kiln, well, we are getting very, very efficient. I have a 7000 watt gas generator just begging to be converted.

You live in one of the places i would love to visit for a few months. the problem is i don't think i could get any work done I would spend all my time out in the bush looking at bryophytes. You can take the boy out of the rain forest but you cant take the rain forest out of the boy. I found that my other weakness of the head gets invoked when i go to places with moss; some times its hard to get me away from the airport grounds cause of the clear space needed they tend to have water and brush features just hanging with cool mosses and liverworts, ferns, club mosses (not true mosses but still cool) Lichens, Ah me. I have wanted to go to Costa Rica for a long time.

I promise not to tell if you want to get lost in the jungle for a while.