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I experimented with the plans that Ianto Evans and Leslie Jackson prescribed in the first draft of ‘Rocket Stoves to Heat Cob Buildings: How to Build a Super Efficient Wood Fired Heater‘. I gotta tell you that it didn’t sink in the first time I read it. I understood it in principle, but it just seemed counter intuitive. The smoke goes down instead of up? Every time I’ve seen fire and smoke it goes up.

The rocket stove is a efficient wood burning device. All the heat is stored in the thermal mass; cob bench, soil bed, wall or floor. By the time the smoke leaves the building it has lost a significant amount of heat and transfered it into the building. So much that you can keep your hand on the chimney top. It’s mostly hot air and moisture leaving the flue.

The rocket stove is a down-draft heater. The oxygen hungry fire sucks air into the mouth of the stove. The fire and air move down the horizontal burn tunnel, in this case made of fire brick, and up into a insulated internal chimney. The insulated chimney was constructed with a clay tube embedded in vermiculite and clay, embedded in a metal cylinder. Then the hot air and smoke moves into a 55 gallon drum, cools ever so slightly, releasing heat into the building and sinks / is pushed into the 8″ horizontal stove pipe. The pipe is embedded in a cob bench, releasing the heat into the thermal mass of the bench there by storing it like a battery. From the bench the pipe leaves out of the building.

Updates:

Here is a of Ianto’s Rocket Stove book.

Read a review by Ocean Liff-Anderson at Dirt Cheap Builder.

The second edition, Rocket Mass Heaters-Superefficient Woodstoves You Can Build (and snuggle up to) is available here:
http://www.rocketstoves.com/