| 摘要 |
PROBLEM TO BE SOLVED: To discharge foreign matter removed by a filtering material in a filtering tank out of a both water heater when bathtub water is drained by back washing even without executing drain piping work separately from a piping work of the heater and to always hold the bathtub water clean even when the tank is cleaned and a plurality of persons continuously bath in the following bath. SOLUTION: The bath water heater comprises a back washing means of a filtering tank 27 for draining warm water heater by a hot water supply heat exchanger 3 from a hot water supply solenoid valve 20 to a bathtub through a lower forward passage 28, a forward and reverse three-way valve 29, a filtering tank 29, a draining three-way valve 24, a drain passage 30 and a forward passage 12, and a control means 21 for displaying cleaning of a bath adapter 19 at an outer input unit 31 when an integration of number of times of the back washing becomes a predetermined value. Thus, even when a drain piping work is not executed separately from a piping work of the heater, a foreign matter removed by a filtering material in the tank is back washed when the bathtub water is drained and drained out of the heater. Even when dirts are slightly stored in the adapter 19 when back washed, a user periodically clean it, thereby always holding the water clean.
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