outdoor furnaces

Thanks,
Phil

Interesting review he gave me. First he complained about having to clean creosote off the fan quite regularly, else it vibrated. He admitted that it produces lots of heat and uses proportionately less wood than his neighbour's Wood Doctor. He heats 1500 sq ft and a 40 X 40 shop in which he works on his combine, so it's a big building.

Apart from the creosote the device apparently works well. The fan on the chimney draws air down through a hopper. The wood sits up high at first, then gradually falls down into the main firebox after it is thoroughly dry. There is very little smoke, apparently, and he said that he could hold his hand over the chimney and feel little heat when it is running full blast.

This fellow loaded the system with prestone -- three drums of it at $1000 per drum. Ulp.

He further commented that the fire burns best if all of the blocks in it are the same size, ideally 6" in diameter or so.

He admitted to burning junk wood, especially poplar, but doesn't link this to the creosote problem. Seems the creosote happens when cold air meets the chimney. I had that happen with an airtight stove back in the '70's, I couldn't keep the flue hot enough to prevent creosote buildup on cold, windy nights.

Oh yeah, the Mennonites build these furnaces, and they deliver when they have them finished, not when you want them. They waited over a year for the unit.

Another guy who looked at his bought one and it had a leak. My advisor blamed the installer for not pressure-testing the unit before firing it up.

And that's all I have learned so far. If anybody knows anything more about these units, I'd like the hear.

College campuses that use a central heating plant distribute the heat by building underground tunnels and routing steam pipes insulated with asbestos through the air filled tunnels. This avoids contact between the heat plumbing and the soil and ground water, which would otherwise "suck the heat right out" of the distribution pipes.

An outdoor boiler 25 feet from one house is one thing, and empirically known to be do-able. Dig a trench, use waterproof insulation around the heat pipes, total heat loss is acceptable.

Hundreds of feet of pipe going all over the yard seems like you would lose so much heat it would seem like bailing out the ocean.

The combustion is extemely important also, since a combined total of 1/8" of build up on the heating surface (ash/carbon) and water surface (scale) will be the equivilant of 3" of asbestos in heat loss. If you clean your system when your effeciency starts to drop you will have a system that could last way beyond your lifetime with a good margin of saftey for your family. I would have the outside walls of the home injected with insulation to entrap the heat loss. You will never regret it. If you put your system outside you will have to heavily insulate it against the environment both above and below ground. HTH in your decision, 45 yrs on boilers, retired and on coldiron now.

However, in your case, I would go with an outdoor boiler. For use in multi-buildings, would seem to be the only sensable way to go.

Locate it for the smoke issue in spring & fall. Many of the 'problems' come from using too wet a wood, just because one can! Make your wood a year ahead & it will work better. There is a lot of debate about stainless steel vs regular steel - stainless won't rust out but it is far more brittle. Rust through or crack through? Not sure who to believe on which is better.

--->Paul