Solar domestic hot water system with thermal siphon preheating

摘要

A solar energy based domestic hot water system which employs a columnar-type heat exchanger designated as a thermal booster having two columns, through one of which passes extremely warm water coming from the output of a solar collector to prewarm colder water coming from the solar storage tank and passing through the second of which columns, on its way to the conventional electric or gas domestic hot water heater. The thermal booster warms the water in the second column primarily during periods when no hot water faucet in the hot water delivery system is in an actuated condition. Optionally a coil heater exchanger may be disposed in the upper section of the storage tank to warm entering cold water from the cold water inlet source prior to its passage through the second pipe as above on its route to the domestic hot water heater. Operation of the system requires minor modification of the domestic hot water heater of the system at its input pipe and by the inclusion of an extra value controlled outlet.