| 摘要 |
PROBLEM TO BE SOLVED: To provide a heat pump type water heater enabling efficient defrosting operation regardless of an installation form and a variations of an object.SOLUTION: When defrosting operation is started (S2), a circulation pump is operated at first predetermined rotating speed (S3), and until rotating speed of the circulation pump reaches minimum rotating speed causing stop of operation of the circulation pump (Yes in S6), the circulation pump is operated while the rotating speed is lowered by second predetermined rotating speed every time predetermined time elapses (S4-S7). When the operation of the circulation pump is stopped before the rotating speed of the circulation pump reaches the minimum rotating speed (Yes in S7), rotating speed obtained by adding the second predetermined rotating speed to the rotating speed when the operation of the circulation pump is stopped is set as new minimum rotating speed (S8), and until the rotating speed of the circulation pump reaches the new minimum rotating speed (Yes in S6), the circulation pump is operated while the first predetermined speed is lowered by the second predetermined rotating speed every time predetermined time elapses (S3-S7). |
