iDRY Vacuum Kilns

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New to the kiln thing

Started by 9shooter, September 14, 2004, 09:29:39 PM

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9shooter

I'm in the process of setting up my wood shop and am also putting in an outdoor wood boiler to heat the shop and the house. I got to thinking that I could make a small kiln outside the pole barn and heat it with a small cast iron radiator. I'm thinking about 4' x 4' x 12' on a cement slab. I would use a fan to circulate air and set up a humistat to control air exhaust. Do any of you guys have any suggestions? Also I will be shopping for a moisture meter. Any suggestions on what to get and what to avoid? I will probably have to set up a selenoid valve/thermostat to control the heat.
Earth First! We'll log the other planet's later!

Den Socling

To dry wood you need to control temperature, humidity and air flow. Air speed is not terribly important but even air flow through the stack is very important.

If you want to turn on/off water through a radiator, consider a slow-closing solenoid valve to avoid water hammer.

A decent humidistat and air exhaust (vent) is more difficult than you are probably thinking. If you don't vent enough, you will get mold and stains. Vent too much and you waste heat and crack wood.

In short, a tiny and simple dry kiln is not impossible but it's not easy, either.

serg

Hello! What temperature of water at you will be applied? ??? Sergey

ElectricAl

9Shooter,

Don't use a cast iron radiator. They are for steam not hot water. Your better off with a custom built radiator or heat exchanger from your outdoor wood burner distributor.

You can also have the pump and fan come on when heat is needed. With a small chamber you may "overheat"  if the pump is left running all the time even while the fan is off.

Depends on how accrete you want to get while drying. Nyle can build you a nice Wet bulb/ Dry bulb controller. That way you can follow standard Kiln Dry Schedules.  The Nyle Controller can turn the heat on and off, vent fan on and off and even add humidity if you choose to hook up that option.

Keep your wood burner set around 150 no more more than 180.  At 180 there is a chance of a boil over if none of the other systems are useing any heat.


ElectricAl
Linda and I custom saw NHLA Grade Lumber, do retail sales, and provide Kiln Services full time.

Den Socling

Al is right about the radiator being designed for steam but you don't need much heat. It might work but fin pipe would be sure to work.

I don't know much about Nyle's controllers but I have 'issues' with those I've seen. Some are much too simple. Some are much too conplicated. Maybe Don can tell us if they have settled down on their own design. We replaced one that was impossible to fix (built by a third party) but it was a few years old. And they were selling Partlow 7000's. The 7000 can work but, as I told Don a couple years ago, they are dinosaurs. As I've said elsewhere in this forum, 'loop controllers' are modern, bullet proof, easy to use and highly configurable to any control task. Elsewhere in this forum were links to loop controllers for a couple hundred bucks.

9shooter

Contrares on the radiator guys. There are 2 basic types of cast iron radiators; one for steam, and one for water. MOST of the radiators out there are for steam, and wouldn't work in a hot water system. The type I bought @$50 each have cross section connections top and bottom which is what is required. The main concern in a hot water system is to keep the ph of the water alkiline and to put in enough rust inhibitor. This stuff reacts with the iron and provides an oxygen barrier on the surface of the innards of the stove/water system.

As for the kiln idea, I was wondering about the corrosive salts that leach out of the wood as it is drying, and if they would attack the outer surface of the iron radiator. I guess I could paint it with aluminum paint to retard/inhibit this action.
Earth First! We'll log the other planet's later!

9shooter

Moving right along...........I take your imput to heart about using a conventional heat exchanger. Maybe I should go get some of that stainless pipe I saw yesterday at the salvage yard and make my own..........I will go to 'school' on the kiln controls though........Thanks for your imput.
Earth First! We'll log the other planet's later!

9shooter

Serg, I have not decided yet, but it will be between 150 F and 180F.
Earth First! We'll log the other planet's later!

serg

Temperature of water in the boiler of heating I apply 200F, in the chamber 170F.
At such temperature it is beautiful to be dried a pine, an alder, a linden, an aspen up to furniture humidity of 6 %.
Thus three valves work only.
2 exhaust, 1 giving air. Pairs constantly is present at the chamber. I have made it on work of vacuum with application of natural movement of air in stacks. Result excellent. The gradient of movement of a moisture in a tree corresponds(meets) to an output(exit) pair. Humidifying is not applied.
Term of drying of 6 days.
Sergey

Don_Lewis

When sizing heat coils, you have to remember that coils are normally rated at 65-70F entereing air and 180F entering water. Because the capacity is directly related to that temperature difference, the capacity at higher temperatures is much, much less. Some of the guys selling hot water boilers don't understand this and sell coils that are too small. Many are also made with the the wrong kind of solder used with copper tubes. Almost all copper tube aluminum fin coils are made with tube walls too thin for kilns and with galvanized casings and with the wrong type of solder or brazing alloy. They work for a while but will leak sooner rather than later. Make sure you get coils specifically made for kilns. 


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