I just happen to come across Rocket Mass Heaters on You Tube and it seems like a really cool idea. I wonder if I could do something like this in a small building. This is basically building a stove out of dirt This would be great as I have been deciding how to build my blacksmith shop behind my garage under the old horse lean too (stable) . I have a crap load of wood to burn but I don't want to use it in the house. That is what my coal is for. This also might be pretty cool to heat water tanks with like a boiler system and use radiators in the Garage and upstairs of the garage that I am turning into an apt.
Anyone heard of these? My ground is clay just a few feet down. Just search You tube for Rocket Mass heater.