So I've been sitting here thinking about rocket stove thermal mass heaters, and it seems to me like a wonderful idea. It cuts down on wood consumption, it has long lasting residual heat, and it uses very simple components. This is all very cool to me, but I wonder if there's another option. I was watching a guy use his wood stove to heat a copper coil with water in it to heat his garage (ran the line to a radiator inside with a fan blowing on it) and thought "hmm, that seems interesting". And the only reason he did this is because he didn't want the fire to be in his house. Then I watched a video about a guy using a fire stove to simply heat hot water for his shower in the same fashion. It made sense to me, people like hot showers. The final video I ran across (I know, youtube addict) had a farmer using the sun to heat his water with a series of tubes running through insulated boxes (I know I've seen the same thing referenced on this website). I was wondering if it might be possible to combine these ideas to use the sun to heat water and run it through a thermal mass "bench" in the house instead of using a fire. I know that water will only get so hot, but the thermal density of a liquid is much higher than that of a gas, so it should transfer a good amount of thermal energy. Also, if it's really not getting hot enough using water, the system could be filled with an oil or other liquid with a higher boiling point.
On the other hand, could this be combined with the standard rocket stove thermal mass heater so that on days when the sun is hidden by clouds, either the fluid line in could be heated or the full vent system could be installed alongside the water line? I hope this make sense. If not, I'll try explaining a different way, but I'd love some input on the topic. I'd love to hear other people's ideas as well!
If i understand you right. I think were supposed to say "never, ever run water through a coil and expose it to bare flames and in general don't blow yourself up." I do believe you can heat a body of water and run a coil through that no problem but someone, I'm sure, will correct me soon if I'm wrong about that. Good luck! Safety First. Check out the wood burning section there's a lot of stuff like this.
http://www.youtube.com/watch?v=5IRLVCJ1olA Whatever system you devise, I do believe the thermosiphon principle should be used because it's so simple. The principle uses the density difference between hot and cold water to drive flow (the higher fluid pressure at the base of the cool water column than the pressure at the base of the hot water column, and the differential pressure results in water flow).
You almost described my system exactly. 8ft x24ft dyi solar water heater (builditsolar.com),1200 gallon solar storage tank, radiant floor heating in 12ft x 44 ft bedroom addition is feed from solar storage tank (open loop), rocket mass heater to help warm solar storage tank (open loop), electric hot water heater feed does several loops through the mass of the RMH then gets pre heated again in the solar water storage tank with 100 ft coil of pex. So yes, your brain storm will work . I also have an additional 1500 watt electric water heater that circulates into the tank during daylight hours to use up energy from pv panel.