Off peak storage hot water central heating - has heat pump to back up off peak electric heaters

摘要

A heating unit provides primary water to a domestic hot water calorifier and to storage vessels which serve space heaters. The primary water return enters a heat pump within the heating unit and flows from the heat pump to continuous flow electric heaters which operate at off peak times on a low tariff. The heat pump can operate at all times. A bypass round the heat pump takes the primary return directly into the electric heaters. Solenoid valves open the bypass and close the return to the heat pump when the return temperature reaches a value at which it is not economic to operate the heat pump. The heat pump is switched off at the same time.