Save energy, make your own fuel efficient wood stoves
TEH three stone hearth is the most common device for cooking on a wood fuel fire throughout Uganda. Over 2.5 million households use it. The three stone wastes 65% of its heat.
TEH three stone hearth is the most common device for cooking on a wood fuel fire throughout Uganda. Over 2.5 million households use it. The three stone wastes 65% of its heat.
This waste can be reduced to about 40% by improving the stone hearth. The improvement requires a wall of clay around the three stones. This wall or cowling can be made by any householder. No special skills are needed. Housewives like the improved three stone hearth. It saves time and can also save babies from burns.
The design:
The shape is a circular wall to contain the heat of the fire below the cooking pot. The pot should rest on the three stones, not on the clay wall. A space of about three fingers width between the wall and the largest pot the cook uses allows for movements of the pot during cooking, allows a draught to draw the fire around the pot, and smoke to escape.
Materials:
Clay-soil or river clay can be used. It needs no special preparation, but should be well kneaded to exclude air bubbles.
The clay should be firmly pressed onto the hearth bed on the outer edge of the stones. Cover the wet clay with banana leaves or plastic sheet while it dries slowly to reduce cracking. When the clay is dry, light a slow fire between the three stones. This is called ‘weathering.’ It helps to harden the clay for use over many years.
Construction: The wall should be five fingers thick or more at its base, and three fingers thick at the top. The opening at the front where the cook sits should be two hand-spans across at the base, and two and half hand-spans at the top. This opening allows the cook to insert woodfuel into the ‘firebox,’ the space between the 3 stones. The cook should sit with her back against the prevailing wind.
If this is not possible, some housewives make a hole on the wall on the windward side of the heart. This creates a good draught, and can be blocked by a stone if the wind blows too hard.
Ends
This waste can be reduced to about 40% by improving the stone hearth. The improvement requires a wall of clay around the three stones. This wall or cowling can be made by any householder. No special skills are needed. Housewives like the improved three stone hearth. It saves time and can also save babies from burns.
The design:
The shape is a circular wall to contain the heat of the fire below the cooking pot. The pot should rest on the three stones, not on the clay wall. A space of about three fingers width between the wall and the largest pot the cook uses allows for movements of the pot during cooking, allows a draught to draw the fire around the pot, and smoke to escape.
Materials:
Clay-soil or river clay can be used. It needs no special preparation, but should be well kneaded to exclude air bubbles.
The clay should be firmly pressed onto the hearth bed on the outer edge of the stones. Cover the wet clay with banana leaves or plastic sheet while it dries slowly to reduce cracking. When the clay is dry, light a slow fire between the three stones. This is called ‘weathering.’ It helps to harden the clay for use over many years.
Construction: The wall should be five fingers thick or more at its base, and three fingers thick at the top. The opening at the front where the cook sits should be two hand-spans across at the base, and two and half hand-spans at the top. This opening allows the cook to insert woodfuel into the ‘firebox,’ the space between the 3 stones. The cook should sit with her back against the prevailing wind.
If this is not possible, some housewives make a hole on the wall on the windward side of the heart. This creates a good draught, and can be blocked by a stone if the wind blows too hard.
Ends