How to Build the Rocket Stove - Capturing heat: Five earth-friendly cooking technologies and how to build them

With a can opener or hatchet, etc. take off the lid of the can.

g        Then cut a 4" round hole in the middle of
It    the lid and a 4" round hole in the lower front
;e.    side of the can, about 1" up from the bottom
;      of the 5 gallon can.
A 4" stove pipe elbow at 90 degrees is
placed inside the can with the larger end
e protruding out the hole cut in front of the can.


Two parallel cuts, 1/2" apart, are made in this protruding section of elbow, on the lowest side of the pipe. This section is folded down, creating a lip so the elbow can't fall
back into the container. n

A straight section of 4" chimney pipe is then fitted to the other end of the elbow as a chimney. It is cut off 1" below the top of the can. (Remember that a short chimney is more efficient. A long chimney will keep flame from hitting the pot. Conversely, a taller chimney will produce less smoke.) The lid, with a hole in the middle, is fitted over the straight section of chimney pipe, after the space between the chimney and stove body is filled with lightweight insulation.

Insulation is small trapped pockets of air. It is this air that slows down heat transfer. Sand, brick, earth, cement, etc. do not contain many





trapped pockets of air and are poor insulators

Examples of good insulation include: pumice rock, vermiculite, perlite, wood ash, dead coral and aluminum foil, if it traps air.

Usually, we use wood ash. As long as it stays dry, wood ash is a great insulator and it is found near fires.

To finish the stove make a pot support, similar to a grill, out of heavy gauge fencing or wire and place it on top of the container. Alternatively, it's possible to rest the pot on top of the container itself. In this case, it's necessary to cut large holes in the top of the container so the air can flow unimpeded past the bottom of the pot. These holes should have the same cross sectional area as the chimney and firebox, in this case 4" in diameter.

Then, make the flat shelf that fits inside the fire chamber and helps to separate the sticks. The shelf can be made out of a flattened tin can and slides into the combustion chamber. The stove will be much more efficient if used with a skirt around the pot. The skirt is simply a sheet of metal that is as high as the pot. The skirt surrounds the pot, leaving an even gap of about 1/4" between the skirt and the pot, so the hot flue gases are directed to contact the pot sides. The skirt gap is equal to the cross sectional area of the chimney. An insulated skirt is double walled with insulation between the walls.

We use the Rocket stove at Aprovecho and we recommend it. It's much easier to use than an open fire and uses less firewood. Please let us know what you think of it. Help us to continue its evolution towards perfection!