| Boiling Point No. 15 - April 1991 |
by Griffin Shay of BOSTID, Washington DC, USA
Researchers in Chile have devised an unusual stove for producing a steady flow of hot water. The stove will deliver about 3 litres per hour of 45° C water while consuming about 7 kg per hour of waste wood. The stove has a simple design. The principal components are two steel drums - one 100 litre drum and one 200 litre drum and some plumbing fixtures, tubing, and sheet metal.
The stove is fabricated by fitting the lid of the 100 litre drum with a fuel/air inlet and a chimney. According to the stove designers, the conical shape of the fuel/air inlet creates a turbulent airflow that promotes a clean burning fire. This smaller drum is the firebox for the stove and is suspended inside the 200 litre drum (figure 1). The larger drum has a cold water inlet and a hot water outlet.
In operation, wood is charged to the firebox and ignited. As the fire develops, cold water in the larger drum is heated and the less dense hot water rises to the top of the drum and passes through the outlet (figure 2). The temperature of the water produced can be controlled by the rate of water flow through the stove. For example, 45°C water is obtained at 5 litres per minute, 75°C water at 3.5 litres per minute and 90°C water at 2 litres per minute.
This stove was developed for use in rural areas where waste wood is abundant and hot water heaters scarce. The hot water can be used for baths, showers (figure 3), laundry, and general cleaning. This stove has been well received in Chile, where about 50 have been built, as well as in Colombo, Peru, and Ecuador.
The stove was designed by scientists and engineers at the Energy Research Centre of the Universidad del Biobio. Additional details on the fabrication and use of this unit can be obtained from Dr Jorge Maldonado Castillo, Energy Research Centre, Universidad del Biobio, Avda, Collao 1202, Casilla 5-C, Conception, Chile.
ED note: A hot water supply is a necessity in many communities such as tea estates and is often very inefficiently provided by an open fire wasting fuel. The idea of the Chilean stove is sound but the description leaves many questions ea.,
• how is the firebox held down against the water pressure?
• how is the large drum lid held on?
• bow is the "-'rebox cleared out of ashes etc?
• as the water may sometimes be drunk, the water cylinder must be kept clean and free from sediments.
• does the fuel need a supply of air from below? how is the stove lit?