PURPOSE: To make it possible to positively obtain hot water in a required amount and at a predetermined temperature without depending on weather throughout a year by providing control means for obtaining an amount of heat subtracting an anticipated amount of heat obtained from a solar heat collector depending on weather on the following day from the required total amount of heat, by an electric heater.
CONSTITUTION: A required total amount Q of heat is obtained by a first arithmetic unit 28 for operating based on output data from desired hot water amount setting means 25 and residual hot water heat amount detection means 25. An amount Q1 obtained from a solar heat collector is obtained by a second arithmetic unit 31 for calculating an amount of heat absorbable into a tank from the collector according to weather forecast. An amount Q2 of electric heat obtained by a third arithmetic unit from output data of both arithmetic units 28 and 31, is supplied to a power controller 36 to control an electric heater, and water is heated. On the following day, water is heated to a predetermined temperature by solar heat and a required amount of hot water is supplied. By these procedures, there is no need to consume power to no avail, and solar heat can be utilized at maximum and a required amount of hot water can be positively supplied.
NISHIZAWA SOTOAKI
OKUDA TAKEO
TANAKA MASAYASU
BECKER KK