| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an electric water-heating appliance, in which operations for water supply and draining are performed by a single valve (a 3-way valve), the constitution is simple, the number of parts are reduced, the space-saving and cost-reduction are attained. SOLUTION: Whether a control board 13 should output a signal for drainage or not is judged on the basis of a result of a thermistor 8, when an input for drainage is received by a controller operation, or when it comes a set time for automatic drainage. If hot-water temperature is at a threshold value or lower, the 3-way valve is energized, a plumbing pipe 4 and a bypass pipe 14 are connected to form a draining line for draining the water of the hot-water storage tank through an overflow pipe 10, and the water of the tank 1 is drained. The 3-way valve 3 is switched to a water- supply state 16 after a lapse of predetermined time (the drainage is finished at this time point), a water-supply pipe 2 and a drainage pipe 4 are connected to form a water-supply line to the tank 1 and water is supplied to the tank 1. When level sensors 6 and 7 detect that the tank has been filled with water, or based on a countdown result of water-supply time, the 3-way valve 3 is returned to a standby state 18 on receiving a signal from the control board 13, and the water-supply is stopped.</p> |
