there's gotta be a way....

[Engineer]

... possibly to use 'surplus' hot water from an outdoor wood boiler to heat a very small (<600 bf) kiln?  Here's the scenario - I have several piles of partially to mostly air-dried lumber of several species.  I have a Central Boiler 5648 unit that has a major heat "surplus" owing to an extremely energy efficient house and good woodburning practices.   What I'd like to do is build a small kiln near the boiler and run heat tubing into the kiln.  I doubt I can get the kiln temp up to 160 degrees to burn off the bugs and set pitch, but I can try to use some of that heat to at least speed up the drying process?  It would be some kind of hybrid system, I guess - a cross between a solar kiln and a ??? (I have no idea).  Is this even worth pursuing?  My drying needs are such that killing bugs and mold is much more important than *time* for drying.  I have no problem putting a load in the kiln and waiting 2-4 months for it to be done.  And quantities would be small.  No more than 600 board feet at a time, maybe much less.  One of the woodworking magazines did a feature on a very small kiln that used a home dehumidifier and some fans and foam panels, but right now I don't have the room for that.  I do have a lot of hot water, though.

[footer]

I certenly don't see why you couldn't do it, especially on such a small system. If it were insulated well, I don't see why you couldnt get the temp up to close to 200 degrees, or whatever temp the water coming out of the boiler is, with an water to air heat exchanger. Most of your air could be recirculated back through the heat exchanger to keep getting hotter and hotter, I would think anyway.

[PineNut]

With a water temp of 185F I can get the kiln temperature up to 155F. I use a heat exchanger and a blower from an old air handler. It takes a little time but get the lumber temperature above 135F for several hours. 

[Mooseherder]

There is a small mention on Page 34 of Sawmill and Woodlot Magazine, March Issue.
The article is about a 9 member consortium trying to address common misperceptions with their industry. Central Boiler is a member. They may be able to furnish you with a plan.
In one of the last paragraphs it says.
     Energy conservation in a sawmill cannot be overlooked. For instance, a kiln might use electricity from a coal-fired plant which emits carbon dioxide and coal pollution. Using wood as a source of energy eliminates the need for electricity, reducing pollution.
Author: April Terreri

[Gary_C]

There is.  I know of a small mill in northern Minnesota that just has a room with in floor heat along with some small water to air heat exchangers and just heats the room. Very little air circulation and must have some vents somewhere, but I did not see them. Has a CL 7260 for all his heat needs. I do not know how much oak or maple he drys, but it seems to work for him.  8)

[solidwoods]

I use a wood fired water heater to heat the shop (4ksq')  house (3ksq')  hot water heater for dog grooming buis, 2000bf kiln ,  8000bf kiln.
Its very do-able

160 is not the temp to sterilize, its 135.

You don't have to get wood hot to dry it,, its about humidity.  Heat is used to sterilize, it also makes the wood soft which has pluses and minuses.

I use the Pola egg discloser for kiln controller and 12vdc water solenoid for temp/vent

Build the kiln in your shop if you can (the heat is nice in the winter,, vent it out in the summer)

I use pex tube for the infloor heat in the 8000bf, and 3/4" steel pipe for heat exchanger.  Furnace squirrel cage fans .
jim

[karl]

My insulated truck box kiln has a Nyle unit- but I bring the temp up with my Central Boiler running through a homemade exchanger in the fan plenum. I used about 300' of 3/4 copper pipe that was free. I'm pretty sure you can reach the 150 degree point. I have no problem, but I also have the compressor generating heat when I set pitch at 160 degrees.
I posted some pics once upon a time.......