| 摘要 |
PURPOSE:To catch dust with a filter and wash off the dust caught by the filter efficiently by a method wherein the hot water in a bathtub is circulated in two directions. CONSTITUTION:A check valve 24, the correct direction of which is a forward direction of circulation for heating the water in bathtub, is provided in the passage of a suction unit 5. When the hot water is circulated forwards for heating the water in bathtub, the flow passage area of the suction unit 5 is made larger in order to circulate the water under low flow passage resistance and at the same time to catch dust with a filter 26 arranged at the inflowing port of the suction unit 5. When the hot water is circulated backwards, the flow passage area of the suction unit 5 is made smaller by the action of the check valve 24 so as to turn the water into high speed jet stream in order to strike against the filter 26, resulting in separating the dust from the filter 26. |
