Off peak heating system with heat pump - has time control for domestic hot water for summer use

摘要

A heating unit contains a heat pump followed by continuous flow electric heaters operating at a low off peak tariff. The unit supplies space heaters through storage vessels and also provides primary water directly to a domestic hot water calorifier. Primary water is diverted to the calorifier by a three way valve controlled by a thermostat in the secondary side of the calorifier. A time control is switched in when the space heating is off. This ensures that the thermostatic controls can turn the heat pump on only during limited times and therefore reduces the frequency of switching of the heat pump. The overall efficiency of the heat pump is improved and unnecessary switching of the electric heaters is avoided.