Patent attributes
A heating system includes a flow circuit carrying working fluid at a set flow temperature to a heat emitting section, an electricity driven heat pump having a first heat exchanger, and a fuel fired boiler having a second heat exchanger. The first and second heat exchangers arc connected to the flow circuit to heat the working fluid in succession. A coefficient of performance (COPSet Flow Temperature) of the heat pump and a break even coefficient of performance (BECOP) are determined, and the COPSet Flow Temperature and BECOP compared. The BECOP is electricity price/fuel price*boiler thermal efficiency. If the COPSet Flow temperature is smaller than the BECOP in a first hybrid mode, an intermediate flow temperature is determined, the heat pump is operated to heat the working fluid to the intermediate flow temperature and the boiler is operated to heat the working fluid to the set flow temperature.
