GRATES IMPROVE EFFICIENCY
Dean Still, April 2003
Damon Ogle and Mike Hatfield observed in their recent trip to Central America that the shelf placed in the fuel magazine of the Rocket stoves
which lifts the sticks of wood up off the floor of the combustion chamber) was frequently put aside by users who first placed sticks of wood directly
on the floor of the combustion chamber and then after a while, on top of the glowing coals.
Damon and Mike wondered whether including a shelf was important. Luckily, researchers become opinionated only if they get lazy...Damon set up a test
stove in the lab and he and I ran nine one hour water boiling tests. The same stove was tested three times with
The amazing Sam Baldwin, in the best book yet written on cookstoves,
"BIOMASS STOVES: ENGINEERING DESIGN, DEVELOPMENT, AND DISSEMINATION"
reported improving efficiency from 18% to 25% by using a grate on a "malgache" metal stove. This represents an improvement of 38.8%, which
parallels our findings.
Grates that allow air to pass under and up through the burning sticks can have a significant positive effect on efficiency.
Both Damon and I also observed that fewer coals are produced by using a shelf or grate. But further testing is needed to determine the extent of the
difference. More hours staring into the fire!