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Document Type and Number:
Japanese Patent JP3487101
Kind Code:

PROBLEM TO BE SOLVED: To permit the optimum freeze prevention at freeze preventing operation by a method wherein a valve is closed and the opening operation of the valve is prohibited when remaining water in a bathtub is detected upon the freeze preventing operation, effected by conducting hot-water to flow in a pipeline for hot-water heating system.
SOLUTION: A freeze prevention control means 65 judges whether freeze preventing operation of the side of a bathtub is necessary or not. A remaining water detecting means 64 detects the existence of remaining water by discriminating whether a water flow switch is put ON or not by driving a circulation pump 44 for reheating. When the water flow switch is turned on within a predetermined period of time after driving the circulation pump 44 for reheating, it is judged that remaining water exists in the bathtub and the freeze preventing operation of the side of bathtub is effected utilizing the remaining water. When a thermal valve for heating 38 is closed, the opening operation of the same is effected, then, bath water, circulating through a circulating flow passage for bathtub water reheating, is heated by the heat exchanger for bathtub water reheating for 10min, for example, to prevent freezing by increasing the temperature. After the freeze preventing operation for a predetermined period of time, the circulation pump 44 is stopped and the thermal valve 38 for heating is closed to finish the freeze preventing operation.

Kawauchi, Kazuya
Application Number:
Publication Date:
October 31, 2003
Filing Date:
November 15, 1996
Export Citation:
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International Classes:
F24D3/00; F24D3/08; (IPC1-7): F24D3/08; F24D3/00


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