CONTROLLER FOR WATER HEATER SYSTEM, PROGRAM FOR CONTROLLING WATER HEATER SYSTEM, AND METHOD FOR OPERATING WATER HEATER SYSTEM

摘要

An operating method in a heat pump hot water supply system of an indirect heating method is provided by which an average COP during a water heating period can be improved and a risk of running out of hot water can be prevented from increasing. For a heat pump hot water supply system (1000) of the indirect heating method, a change in heat transfer efficiency of a second heat exchanger (29) is estimated by using either or both of a tank water temperature and a temperature of a second refrigerant flowing through a water circuit (21). When the heat transfer efficiency is determined to be high, an operation switching unit (3) raises an output of a heat source device (20). When the heat transfer efficiency is determined to be low, the operation switching unit (3) lowers the output of the heat source device (20).