| 摘要 |
PURPOSE:To make it possible to automatically drain water by providing in the water heating apparatus a shape memory alloy which constantly closes a water drain cock and open the same when the temperature reaches a temperature before freezing by expansion or contraction, and a shape memory alloy which holds the intermediate part of a flexible pipe leading to a hot water supply port in a constantly upward inclined state and expands or contracts the same in a downward inclined state when the freezing temperature is reached. CONSTITUTION:After using the apparatus a master gas cock 29 is first closed, a master supply water cock 30 is closed, an operating button 1 is depressed, hand is released, and a stop valve 14 is opened. When indoor atmospheric temperature becomes 3 deg.C or lower, a shape memory alloy 38 abruptly contracts and at the same time, a water drain cock 37 is pressed down by the force exerted by a spring 33, O-rings 34, 35 and 36 are opened, air makes ingress into the apparatus through a water drain hole 39c provided in a valve guide screw 39a, and water within the apparatus is drained through a hot water supply port 50 and a water drain hole 39c. In a similar manner, when the indoor atmospheric temperature becomes 3 deg.C or lower, a coil-shaped shape memory alloy 44 abruptly contracts and at the same time the flexible pipe 50a of the hot water supply pipe is pressed down by the force exerted by a spring 43, and water is drained through the hot water supply pipe 50.
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