Long term performance of thermosyphon solar water heaters

Abstract The performance of 6 thermosyphon solar water heaters was measured while the systems were supplying typical domestic hot water loads. The effect of system configuration, daily load draw off times and off-peak vs continuous boosting was studied. In contrast to forced circulation systems the performance of thermosyphon systems was found to be best if a morning peak load pattern was used. Operation with off-peak boosting was found to improve the annual contribution by 14 per cent.