A simple low-cost solar water heater

Abstract

SYNOPSIS The objective of this paper was to develop a domestic hot water system to satisfy Thai user requirements i.e. low cost (not over 2,000 baht/m2), warm water, and a simple design which could even be built by the user himself. This objective is accomplished by using commercial PVC pipes (1.5″). CPAC board was installed at the back acting, therefore, as absorber and storage for solar energy. Both covered and uncovered collectors were tested in two orientations: a west wall and a tilted, south-facing surface. The water capacity was limited to 35 litres. Water was withdrawn at different times of the day. Experiments were performed between March and June 2000. With the covered, mounted roof collector, temperatures as high as 72°C were obtained, whereas with the wall configuration, the temperature was about 65°C. To avoid damage to the PVC pipes caused by temperatures above 60°C, air was permitted to circulate between the cover and the pipes. It is concluded that the plastic covered CPAC-PVC pipe collector with appropriate openings at the top and bottom for air circulation seems to be very interesting. Due to the low-cost, simplicity of design and wide availability of materials used throughout the country, application of the design concept developed here is very promising. In addition, the installation of the solar water heater offers another extremely important benefit as it allows the heat gain through the building envelope to decrease.