I have only just begun to look into these rocket mass heaters, and its a fascinating idea. I do have one question at the moment though - the area that you put the wood in to be burned, why is it always so short? Couldn't it be made taller for a sort of gravity feed effect? I dont really have any dimensions in mind yet, nor do I know what I would build it out of even. My uncle has been talking about salvaging a regular wood burning heater from our old house so that he can do away with his propane heat. I remember when we used this heater and its efficiency is just absolutely awful so this whole situation has me thinking about a better way to accomplish this task. His house is quite small so I think a thermal mass heater would work quite well. If I get the chance I will probably build a few smaller heaters for our various shops and other less flammable work areas before I do one for a home.
hope everyone had an enjoyable holiday