| 摘要 |
PROBLEM TO BE SOLVED: To provide a storage type water heater capable of suppressing a sharp temperature rise of tapped hot water when a hot water supply operation stops, in the case when the hot water supply operation starts during a boiling operation.SOLUTION: A rotational speed of a circulation pump 19 is controlled so that a temperature of hot water tapped from a heat pump unit 3 agrees with a target temperature of the tapped hot water during a boiling operation. When a hot water supply operation starts during the boiling operation, a risk factor Z is calculated using the target temperature of the tapped hot water and a difference between a rotational speed X of the circulation pump 19 immediately before the hot water supply operation and a rotational speed Y thereof during the hot water supply operation. When the calculated risk factor Z is larger than a predetermined value for determination, a flow regulating valve 25 is controlled to the closing side. When the flow regulating valve 25 is controlled to the closing side, the rotational speed of the circulation pump 19 is raised. Afterwards, when the hot water supply operation stops, an opening of the flow regulating valve 25 is restored to its initial value before the start of the hot water supply operation. |
