| Boiling Point No. 15 - April 1991 |
Boiling Point carries detailed profiles of improved stoves being promoted in one or more countries. These profiles are reproduced from ITDG's manual "Improved Wood, Waste & Charcoal Burning Stoves" . If any reader has improved the design or construction of any of these stoves we should like to hear from you and publish details. A free copy of the manual will be sent in return for any details of improvements published.
The Nada Chulha is an Indian multi-pot, woodburning, mud stove with a chimney. These stoves can be built in different shapes and sizes in accordance with individual households' needs, kitchen space available and the user's aesthetic preferences. The stoves are usually built on the floor from sun-dried mud slabs, soil and a special clayfibre mix. The stoves are fitted with metal doors and dampers.
The only fixed dimension is the internal height of the firebox - 17cm. An average sized two-pot stove, popular in the plains, measures 70cm x 40cm x 20cm and has a 7.5cm diameter asbestos cement chimney. (We trust that a less dangerous material than asbestos is now being used).
History and Field Experience
This stove emerged as a spontaneous response to the need for smoke removal, made by some women of a village in north India. Other benefits of the stove were protection from excess heat, improved general cleanliness of the kitchen, reduced cooking time, provision of warm water and cooking fuel savings.
Initial attempts at replication of this model in other areas highlighted the need for proper training of stove builders (women) and for devising a suitable organizational structure for dissemination. Dissemination is now only done through collaborating organizations committed to thorough training for builders and to the provision of the necessary support for effective dissemination.
A few thousand stoves were built and as a result it has been included among 15 stove models recommended for promotion under the Government of India's 'National Project for Demonstration of Improved Stoves'. This has led to a large number of training courses and many thousands of the stoves have now been built as a result.
Construction and Installation
The size of the stove is matched to the pots that will be used and pot spacing is measured with hand measurements. The stove layout is then drawn on the kitchen floor. Dried mud slabs 1.8cm thick are made in moulds and used to make a skeleton structure for the firebox, tunnel(s) and the outer walls.
The space between the firebox and tunnel walls and the outside is either filled with soil or left hollow. The inner walls of the firebox and tunnels are then coated with a 2cm thick layer of a clay-fibre mixture that withstands high temperatures. The firebox entrance and the tunnel are roofed with pieces of mud slabs and the stove is finished by applying more of the clay fibre mix on the top and the outer walls of the stove, leaving the pot-holes, moulded to the size of the pots. The chimney is installed with a proper rain sealing at roof level and a chimney cap. The stove is allowed to dry completely for 2-5 days before lighting fires of gradually increasing size.
The chimneys and tunnels must be cleaned out regularly because they will clog up in 2 to 3 months when wood and agricultural wastes are used as fuel. If there is erosion or cracking of the stove body, repairs should be made by wetting the area and applying more of the clay-fibre, taking care not to change the dimensions significantly. The stove might have to be rebuilt every 3 or 4 years by the local trained stove builder.
Use of the Stove
The stove can be made for the use of 2 - 3 pots and an optional attached oven, depending on the needs of the household. A set of sliding doors is provided on the front of the stove. These are especially useful for retaining heat in the stove body between cooking sessions and for protecting the cook from excess heat.
For baking traditional unleavened bread in the firebox mouth, the height of the mouth can be increased by sloping the firebox floor downwards near the opening.
The damper is used to regulate the overall draught and power output is controlled mainly by maneuvering the fuel.
When heat sufficient to bring pots to the boil is required in three pot-holes, the firebox is connected to the chimney by 2 parallel tunnels with one pot- hole above each. When the third cooking hole is desired only for keeping food or water warm, a single tunnel is used. The parallel tunnel stove is extremely popular in mountainous areas and users report substantial fuel and cooking time savings..