What if there was a way to heat your home that uses up to 90 percent less wood than conventional wood stoves, with a system that could be built in a day and a half, for less than $20?

Yes, seriously.

A rocket mass heater is an innovative and efficient space-heating system developed from the rocket stove and the masonry heater, and one that is gaining popularity in natural buildings and within permaculture designs.

These systems incorporate a simple J-tube rocket stove, a metal drum to direct the flue gases down and into a system of ductwork, and finally a great deal of thermal mass (usually a cob bench) to soak up all the heat. Wood is fed into B (the feed tube), it is burned in C (the combustion chamber), re-burned (smoke and all) in E, then the hot gases move into a low pressure area (G, H and J), and travel through K (the duct work) and finally out C (the chimney). All the while, the hot gas moving through the system is being sucked into the thermal mass—usually a cob bench, warming the area with beautiful radiant heat.

This could be the cleanest and most sustainable way to heat a conventional home. Some people have reported that they heat their home with nothing more than the dead branches that fall off the trees in their yard. And they burn so clean, that a lot of sneaky people are using them illegally, in cities, without detection.

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