Rocket mass heaters are an innovative cross between a rocket stove and a masonry heater.
Using a tenth less fuel than a conventional woodburner, a rocket mass heater converts the burn of hot gases that rise from the fire into heat, as well as the heat from released steam and carbon dioxide.
The rocket mass heater is an efficient and clean method of heating your home.
How it Works
Sticks placed vertically in the stoke hole burn from the bottom. They actually burn sideways as this is where the flue to the next stage is. The flames and hot gases are drawn up into a metal barrel where secondary combustion takes place and much of the heat is radiated to the room. The remaining hot gases, now mainly carbon dioxide and steam, exit side-ways via a serpentine duct through a cob and masonry bench, giving up much of their heat in the process.
Rocket mass heaters use only about one tenth of the wood that a conventional wood burning stove would to achieve the same room temperature. They do not suffer from tarring as the secondary burn in the heat riser barrel consumes any contaminants. The burn is so clean that people have used them illegally in smokeless zones without detection. The only prerequisite is that the barrel and flues need to be hot enough to draw the fire sideways through the system. Like all wood burners, the quality of the fuel is key to achieving an efficient burn and only well seasoned hardwood such as oak should be used for optimum results.
A cob style rocket mass heater is 'the old reliable'. The cob insulates the drum and the pipes, taking in the heat and slowly releasing it into the room.
The difference with these is that the mass is usually a wood bench filled with pebbles and rocks. A different aesthetic. These designs are (relative to cob style) easy to move and modify. They also tend to be lighter, thus, better for installing in places that have a wood floor.
This is the main system of the rocket stove as one piece of equipment, making it even easier for people to build their own.
The ring of fire
A circular rocket mass heater with glass to show the burn, creating: it an outdoor rocket mass heater/cooker/smoker, a 'batch box style' rocket mass heater with measured output cleaner than anything we have ever encountered; an indoor rocket stove, griddle and water heater.
Paul Wheaton from Permies.com is running a Kickstarter, raising money to create a DVD set teaching how to make these various styles of rocket mass heater and more. There will be four DVDs, one for each of the styles above. For more information or to support this kickstarter visit www.kickstarter.com/projects/paulwheaton/rocket-mass-heaters-4-dvd-set/description
Watch: Rocket stove kitchen
Watch: Cobb rocket oven
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