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Insulated Clay Combustion Chambers

Aprovecho Research Center began building Lorena earthen stoves in 1976. Testing of these stoves showed that the earth was, in fact, absorbing heat that could have helped to cook food. Also, the heavy earthen walls around the fire kept the fire colder than necessary, creating unhealthy smoke. Aprovecho researchers began looking for alternative materials and methods of designing stoves. They learned that a simple insulated combustion chamber shaped like the capital letter "L" helped to save biomass and decreased smoke when cooking.

The following slide show details how to create a 6 brick combustion chamber made from inexpensive and locally available materials. Light weight, insulative, heat resistant bricks can be made from:
  • vermiculite 85% and clay 15%
  • pumice 85% and clay 15%
  • sawdust 50% and clay/cement 50%
  • charcoal 50% and clay 50%
  • perlite 85% and clay 15%

The bricks are shaped in a form, dried and then fired in a kiln at 1950 F (1000 C). Presently, Dr. Margaret Pinnell at the University of Dayton and Dr. Dale Andreatta at S.E.A., Inc. are testing the recipes for durability and effectiveness in stoves. Sawdust/clay bricks have been used in stoves for one year without breaking.

The 6 brick insulative combustion chamber can be surrounded by mud and then looks like a normal earthen cooking stove. But, the stove will be easier to light, easier to keep going, use less wood and produce less smoke. Aprovecho will be completing a booklet on these techniques in the following months.

1: Weighing clay, measuring water

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2: Six brick molds

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3: Measuring vermiculite

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4: Adding liquified clay 15% by volume to 85% vermiculite by volume

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5: Mixing liquified clay and vermiculite

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6: Filling molds

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7: Filled molds

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8: Drying bricks

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9: Six bricks after being fired in a kiln at 1950F (1000 C)

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10: Six fired bricks make an insulated Rocket stove combustion chamber

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11: Each 12 inch (300 mm) tall brick weighs 1.5 lb. (2 kg), about half the weight of water by volume

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12: Cutting a 4.5" x 4.5" (115 mm square) opening in the six brick combustion chamber

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13: The six bricks form a 12" (300 mm) tall hollow highly insulative cylinger with walls 2.5" (65 mm) thick

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14: The stove body can be made from a used steel drum or mud and sand

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15: A 4.5" x 4.5" (115 mm) square opening makes the fuel magazine

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16: A shelf holds burning sticks of wood above the floor of the combustion chamber

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17: The mold makes the six brick combustion chamber, placed inside black stove body made from 16 gallon steel drum

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18: The paint needs to be burned off the steel drum

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19: The removable lid becomes the top of the stove body

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20: Three bolts serve as the pot supports

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21: An adjustable pot skirt greatly improves fuel efficiency

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22: Pushing the handles together reduces the diameter of the pot skirt

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23: If the steel drum is found, the stove materials cost about 4 USD.

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  • www.efn.org/~apro

Contributors

- Contributors can sign and date articles they have contributed to here -
For any further inquiries please contact:

Dean Still,
Director,
Advanced Studies in Appropriate Technology,
Aprovecho Research Center,
www.efn.org/~apro, email: m{dstill@epud.net}m




Last edited by Miriam Hansen .
Page last modified on Thursday September 16, 2010 10:34:06 GMT.
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