Rocket mass heater and hydronics.

I think rocket mass stoves are interesting, and have been looking into them.

I started to wonder how would best way to heat water to pipe through a floor. So I got to thinking, what if a copper coil was wound around the exhaust within the thermal mass, or a coil was incorporated into the thermal mass. I am sure it varies from stove to stove, but how hot does the thermal mass get 5 or 10 feet from the barrel? The trick would be figuring out where the water could pass through that would be that would heat the water to a desirable temperature, a pump to circulate water through the system into an insulated reservoir.

It would work kind of like a radiator. The thermal mass takes in and heat, the water in the coil transfers heat in the thermal mass to a much larger thermal mass.

It seems like it would be a pretty low pressure system, the reservoir would probably need some kind of pop off valve or a small hole in the reservoir so that steam could vent, a copper coil could turn that steam back into distilled water. I don't really see much of a way that it could explode. My main concern would be building one and having the water get too hot and the floor being too hot to walk on. I guess after a certain point the pump could just be turned off and the water would stop circulating.

I am sure that a lot of things could vary greatly, but I wonder things like where the best place to put a coil would be, and the length of the coil exposed to the mass to avoid turning a lot of water into steam but still heat the water enough to warm the floor efficiently.

Alex Hamond :Welcome to permies.com and our sister site, richsoil.com ! And a big Welcome to our Rocket and Wood stoves Forum Threads. With over
18,000 fellow members you will always find someone here that wants to talk to you about what you want to talk about !

Actually you have quickly grasped many of the key points of hydronic heating and went right to the heart of the system the 1st 10' - 12' of the horizontal
Exhaust pipe, and clearly you have given running the system as a low pressure system with safeguards some serious thought !

However, shutting down the circulation pump with a fire in the Rocket Stove can potentially trap water that could flash to steam because you created the
very same condition you were working to avoid !

You could hardly avoid this trap, as a working hydronic Heater has so many interconnections that need a successful integration within a system that works
best by being frequently attended to maintain a fire for ~6~ to ~8~ hours to provide ~20~ to ~24~ hours of heat stored within your Thermal Mass.

The fact that a Rocket Mass Heater R.M.H., can not be safely operated with a damper to control draft, as a conventional wood stove can, means that due
to operator error a fire can be maintained at the very time that any failure to keep circulating water through the system, like a power outage, can lead
to an accident.

Please use the search feature found in the permies toolbox from the top right of this page, and enter 'Boom Squish' in the google search engine and do a
google search within Permies. Read the Thread comments by ether Ernie or Erica Wisner ( Stewards for these Forum Threads ), they can explain the
issues clearly and with fewer words than I Can ! Hope this helps a little, keep coming back !

As always your comments and Questions are solicited and are welcome ! Think like fire, flow like gas Don't be the Marshmallow PYRO - Logically Big AL !