PURPOSE: To heat water in proper time by controlling the operating time, by calculating the necessary operating time of a heating source from the capacity of hot water to be stored, and the difference between the calorific value to be stored, which is calculated from the temperature in feedwater, and that in residue hot water.
CONSTITUTION: A processor A 7 calculates the calorific value to be stored from the detected temperature in feedwater by a feedwater temperature detector 6, and the capacity to store hot water in a hot water tank, and the necessary operating time of a heating source is calculated in a processor B 9 from the difference between the calorific value in residue hot water detected by a residue hot water detector 8 and that calculated by a processor A 7. Then the operation of a heating source is stopped by a timer unit 10 at the time when the necessary operating time has passed.
SHIMAO AKIRA
INADA MINORU
KUBOTA HIDEJI
HARA KAZUO
ITOU YOSHIKAZU
MITSUBISHI ELECTRIC CORP
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