The farm has three outdoor wood-burning furnaces in use at each household. The oldest is a Central Boiler model that has heated my home for 16 years. We've replaced the door twice but other than that, it's been a solid performer. At first, people would stop to ask if we sold meat cured in our "orange smokehouse". Nowadays they are a common sight.
The second is the Mahoning that heats Dan's parent's house and the equipment workshop. It's the second or third replacement for the same type of model and has lit the wood pile next to it on fire at least twice. Cheap and ugly, it gets the job done. It's as environmentally unfriendly as these furnaces get, and it needs to be replaced. Note the buckling center seam and askew lower ash removal door. Mahonings are too far behind the times to be legal for sale in Vermont any longer.
The newest furnace on the farm heats the milking parlor and Dan's brother Denis' house. It's called Sequoyah Paradise and is replacing two previous furnaces (one or two of each of the above). It uses a process called gasification to re-burn the fumes from the fire to reduce emmisions, and features front doors that hide the black smear that forms above the actual furnace door.
Burning tree-tops and scrub-wood from our managed forests has been practical, but they don't make the furnaces like they used to. Denis' newest Central Boiler model lasted only three years and had design flaws that the manufacturer and dealer refused to replace, nor would they reimburse repairs. The Sequoyah has yet to be field tested, but it should be the wave of the future with its favorable EPA rating.
