Chapter Three
Basic Features of Improved Mud Stoves
All improved biomass stoves have some common characteristics. They include an enclosed burning
box or fire chamber, insulated walls, and in some cases, close fitting links between the pot hold and
the pot. The basic features of an efficient mud stove are related to the dimensions. Dimensions affect
other aspects such as how long the stove will last, cost of production and how it will be used.
The features described in this section help the reader understand the basic rules of thumb that
are occasionally used by mud stove promoters. It is not possible to generalise these but some basic
guidelines are drawn to help in the dissemination of mud stoves.
One of the most important features is the thickness of the wall. This affects the performance of
mud stoves in various ways. The thicker the wall, the better the stove since thick walls conserve heat
and reduce chances of cracking.
Figure 3.1 Thick walls improve performance of stoves
Figure 3.2 Chimney should be at an angle to the pot
holes
However, when the stove is new, thick walls slow down the heating process during the initial
stages of lighting as the wall gets heated up. Once the walls are heated most of the heat from the fuel
is used to heat the pot and the wall acts as an insulator, thus improving the stove performance.
The chimney should be placed at an angle in relation to the smoke channels to minimise heat
loss. This helps retain the heat in the fire chamber.
Figure 3.3 Height of the fire chamber
Figure 3.4 Position of the doors in a two-door stove
The height and size of the fire chamber affects the rate of heating of the pot. If the chamber is
too low, the fire will engulf the pot resulting in wastage of fuel wood. However, many people
mistakenly believe that their food will be ready in a shorter time when the pot is surrounded by flames.
A very high chamber, on the other hand, places the pot far above the flames and uses a lot of fuel
wood. This is because the pot takes more time to heat up.
For a two-door mud stove, the fire entrances must be positioned adjacent to each other
(forming a v-shape towards the pot hole) to allow wind to blow into both holes. Wind should not blow
right through the fire chamber, that is, through one hole and out of the other.
The recommended during period of a freshly-moulded stove should be strictly observed to
avoid cracking, which affects the stove’s efficiency and lifespan.
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