Hello to all. My name is Mike and I am more or less a lazy prepper. I am planning on moving this fall to an area near Pittsburgh and hopefully buy a small hunting camp or some such setup with my brother and his wife.
Please try to excuse my digression as my mind not only wanders, it sometimes leaves me altogether . . . . .
Hypothetically let's say we use a 55 gallon drum for our furnace. We all know the basic setup, but to improve heat transfer/dissipation could we weld fins on the sides of the drum. They would run at an angle going upward to the front. This would add additional surface area for heat transfer. It would also give a subtle 'push' to the heat released so that it would go forward into the room, to a degree, instead of straight up.
3" or 4" 'duct pipe' could be welded to the sides of the drum. Each end (both top and bottom) would be facing forward into the room. This would cause a draw at the bottom to pull in cool air from the floor and again force warm air out into the living area instead of straight up. Once started, this would create additional circulation in the room.
I feel that the 'duct pipe' scenario would work best to increase surface area AND force more warm air into the living area.
Now then, would this adversely affect the combustion in the top of the barrel? By increasing surface area one might think that the internal temperature could possibly be lowered. I realize that this could affect the efficiency and possibly the natural operation of the furnace. Obviously this would need to be put to the test. I myself will not be able to try this until I move, but it seems like it might make the heating more efficient and comfortable. Just a thought.
Efficiency should be used to describe the amount of heat which is extracted from the wood during the combustion process. What you are discussing in this post is what to do with the heat after it has been created.
In a proper j-tube combustion system, combustion is complete after the exhaust leaves the top of the heat riser. Consequently, there shouldn't be any combustion in the top of the barrel.
I admit liking bells better than the steel drum/cob bench approach. If you store the heat in fireclay brick or cob, infrared heat is in play rather than circulation of warm air. This is a different basic principle from the forced air approach you might be using now. It is also more comfortable. A large warm object radiating heat in the middle of your space actually feels warm and makes controlling the warm air less of a priority.
im pretty sure i have seen benches with ducts in them, for this reason mike. it does seem feasible to move some air via heat. from what i understand, the better the exhaust cools in the barrel the more push it has on the bench.