Summary
A commercial, domestic solar water heater was tested in Manaus during the whole year round. The performance was monitored using various parameters: incident solar radiation, temperature of water in the tank and at the entrance and exit of the collectors, as well as the velocity of the thermosiphon The latter was measured by injecting printing ink into the pipework which was fitted with transparent plastic windows in appropriate places. The efficiency of the collectors was seen to vary during the day. The maximum value ever observed was 58% and values of 37% are calculated for the data described In detail. Collector angle in the range 4°—25° did not affect performance significantly Hot water for showers (150 l) at > 45°C should be obtained in 93% of the days of the year.