| Boiling Point No. 07 - December 1984 |
This article was drafted by ITDG and edited by "Is Madhu Sarin who has been working with improved mud stoves in North India for several years.
Description : The Nada Chulha can be built in different shapes and sizes in accordance with household needs, constraints of kitchen space and aesthetic preferences of users. The internal height of the firebox measuring 17 cm is the only fixed dimension. An average two pot stove popular in the plains measures 70 cm x 40 cm x 20 cm and uses a 7.5 cm diameter asbestos cement chimney. In mountainous areas, three pot square, T or L shaped stoves with two tunnels are more popular and use 10 cm diameter tin chimneys. The stoves are usually built on the floor using sun-dried mud slabs, soil and a clay-fibre mix. -m e asbestos cement chimneys cost $2.50, the metal doors and dampers cost $1.00 - $1.50, and the construction and follow-up fee is about $2.00.
History and field experience : This stove emerged as a spontaneous response to the expressed needs for smoke removal made by same women of a village that was part of an innovative participatory erosion control and irrigation project in Haryana, North India. As well as smoke removal, other benefits were protection from excess heat, improved general cleanliness of the I kitchen and house, reduced cooking time,) provision of warm water or room heat if wanted, cleaner pots, cooking fuel savings and reduced overall time and labour required for cooking related work. Since the beginning the Nada Chulha (named after the women of Harijan Nada who participated in developing the technology) has been seen as a technology system, not a technology fix. Because it is designed to provide a wide variety of end benefits and be very adaptable it must take into account 'natural processes such as reconstruction, relocation, demand for new stoves by newly formed families, the proper repair and maintenance of already) built ones, and most important, educating users to use the technology to optimum advantage'. To accomplish these goals women builders who also use the stoves! were trained to build the stoves for) others for a fee.
Initial attempts at replicating the model in other areas highlighted the need for proper training of stove builders and devising a suitable organizational consequence, dissemination is now done only through collaborating government or non-government organizations who are committed to imparting thorough training to builders and providing the organizational support required for effective dissemination by them. The core of the strategy is to establish a new type of village artisan, the 'chuIha mistri'. The 'chulha mistri' (who should be a local woman wherever possible) may be self-employed like other village artisans. In some cases it might be a full-time trade or even a full-time job but it could also be a part-time occupation providing supplementary income to a low-income woman. A group of 'chulha mistris' have at least one supervisor/project coordinator for a minimum support period of six months. The job descriptions and selection criteria for each of these, namely, chulha mistri, supervisor and project coordinator are provided to collaborating organizations.
The technology, organizational structure and training methodology have developed to meet the needs of the beneficiaries. Initially, the full cost of the stove was paid for by the owners. However, to ensure that even poorer households are able to afford the stove, partial or full subsidies have been introduced. Emphasis on development of local skills, regular monitoring of performance and helping users understand the technology combined with the definite desire for chimney stoves among women to reduce their drudgery related to cooking have all been critical in the success of this project.
A few thousand stoves have now been built and it has been included among 15 stove models recommended for promotion under the Government of India's 'National Project for Demonstration of Improved Stoves'.
Performance : No laboratory tests have been published on these stoves but extensive monitoring of the users has shown that most users perceive a significant (25-50%) fuel saving and, more importantly, a number of other improvements in performance mainly related to the cleanliness, ease of use, time savings and provision of extra amenities.
Construction, Installation and Maintenance The size of the stove is matched to the pots that will be used and pot spacing is measured with hand measurements. The layout is then drawn out on the kitchen floor. 1.8 cm thick dried mud slabs 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 filled in with dry soil or left hollow. The inner walls of the firebox and tunnels are then coated with a 1 to 2 cm thick layer of a clay-fibre mixture that can withstand high temperatures. The firebox entrance and the tunnel are roofed with pieces of mud slabs and the stove finished by applying more of the clay-fibre mix on the top and outer walls of the stove with pot-holes moulded to 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 to 5 days before fires of gradually increasing size are used.
The chimneys and tunnels must be cleaned out regularly because they will clog up in two to -three months when wood and agricultural wastes are used as fuel. If}there is erosion or cracking of the-stove body, the area should be wetted and new clay-fibre mix applied without significantly changing the dimensions. The stove might have to be rebuilt every three or four years by the locally trained stove builder.
Use of the stove :The stove can be made to use two to three pots and an optional attached oven depending on the needs of the households. A set of sliding doors are provided on the front of the stove. These are especially useful for retaining heat in the stove body in between cooking and for protecting the cook from fire heat. For roasting traditional unleavened bread in the firebox mouth, the height of the mouth can be increased by sloping 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 adequate heat for bringing pots to the boil is required in 3 pot-holes, the firebox is connected to the chimney by 2 parallel tunnels with one pot-hole above each. When a 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.