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close this book Boiling Point No. 06 - April 1984
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View the document The introduction of an improved charcoal cooking stove in juba, Sudan
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View the document Consumption of Firewood in Rural Areas
View the document Charcoal Kiln Testing in Thailand
View the document An Inexpensive and Efficient Mini-Charcoal Kiln
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User Modification of Charcoal Stoves

Bill Stewart

ITDG Stoves Project

In a number of Asian countries groups involved in developing and disseminating more efficient stoves have been shifting towards the use of prefabricated ceramic stoves. While there are many advantages to this approach one significant criticism has been that prefabricated stoves reduce the ability of the users to tailor the stove to meet their specific needs. The experiences of three tea shops in Malekhu, Nepal, shows that individual adaptation is both possible and useful.

In Nepal UNICEF designed and is promoting, through the Agricultural Development Bank, the two pot ceramic stove shown in Figure 1.



It was designed primarily for domestic use and has been well accepted in a number of villages.

Malekhu is a small bazaar 80 km from Kathmandu on the Kathmandu-Pokhara road. Previously UNICEF has given technical assistance to install a micro-hydro energy system for agricultural processing and the provision of electricity. This was followed by the introduction of some ceramic stoves. A number of tea stalls installed the stoves but felt that the stoves did not meet their specific needs, even though the stove was saving wood.

One of the first users (a doughnut maker) felt that the 22 cm and 18 cm pot-holes were too big for his little kettles, but too small for his big pots. So on one stove he reduced the diameter to 17 cm by lining the inside of the firebox with a fairly fire resistant clay. He also ordered a stove with larger pot-holes that were farther apart for his large pots, and connected both stoves to one chimney (see Figure 2). On the larger stove Andreas Bachmann of UNICEF gave the owner a cast iron grate. The owner chipped a hole in the base of the firebox and dug a separate primary air tunnel to go underneath the grate. This increased the power output by more than 50% and also made it possible to burn large 8 cm diameter logs. Because he uses both stoves at least 12 hours a day the chimney must be cleaned every two months. The proud owner claims the cleaner stoves have made the cooking easier and reduced his daily consumption from 20 logs to 6 logs per day.

FIGURE 2: Two adjoining stoves connected to one chimney with other modifications made by the owner (see text)


Another tea owner, with a smaller shop, made a different modification. The two pot-holes were large enough but he needed a third pot-hole to keep a small pot of milk warm but not boiling. His solution was to chip out a hole at the back right hand side of the firebox and lead an 8 cm diameter tunnel up to the surface. m e milk pot sits on top of the tunnel and is raised up on three knobs. The slight gaps allow a small amount of flame and heat to be drawn up to the pot to keep it warm, but most of the smoke is drawn out through the chimney.

Further up the road another tea stall owner saw the new stoves and their benefits but did not want to wait to get a ceramic liner. The first tea stall stove's mud firebox lining had not cracked which shows that the local mud is quite heat resistant. The owner took a section of a ceramic pipe to make the firebox entrance and copied the ceramic stove design faithfully out of mud. Except for a slightly lower back baffle his stove is an exact duplicate of the ceramic stoves. He also put in a metal back damper, fabricated a 10 cm diameter chimney out of oil tins, and made a good rain cap on his 1.7 metre chimney.

These examples show that tea stalls have different cooking needs from households and that owners can modify or copy a single ceramic stove design to meet their own needs.