This is a crazy idea but I just have to tinker.
I follow Slim Potatohead's adventures and I'm impressed with his homemade pellet stove for his camper. I don't have much in metal working skills so I'm pursuing an approach using an alcohol stove. Ideally the stove will operate outside of the cabin and somehow a water line will pass through a heat exchanger and via thermal expansion will rise and enter the cabin where another heat exchanger, maybe with a small case fan will capture the heat from the water and return to the stove and reheat.
So far I'm in the initial stages of building the stove. I have a ways to go. The prototype stove is only a 10 oz jar. I hope to fire it up in the next few days and see what kind of burn time I'll get. I've done the beer can alcohol stove before and know that it gets only about 15 minutes per oz of alcohol. They are not known for efficiency and a lot of the fuel in them is used up priming and warming the stove. Maybe ten oz will get me several hours?
I'm thinking the water line transfering the heat from stove to cabin will be a closed loop. At the stove that line will run through a bath of hot water and not be exposed directly to the flame. I would use an expansion chamber on the closed loop. Maybe a pressure relief valve of some sort as well.
While waiting for the stove adhesive to set I'm trying to come up with a wick that I can use to drive the fuel into the copper tubing. Not sure what I'll use there but I've seen people use bamboo skewers so I'll give that a go.
Stay tuned...