Abstract: 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.

Abstract: 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.

Abstract: A heating installation includes a heat pump, heating fluid piping passing through a condenser of the heat pump to exchange heat between refrigerant and heating fluid, first and second objects heated by the heating fluid to first and second set temperatures, a valve switchable between first and second positions to supply heating fluid to the first and second objects, sensors detecting first and second actual temperatures at the first and second objects, and a control. The heat pump also has an evaporator, a compressor and an expansion device. The control in a demand dependent mode, is configured to determine a first demand based on the first set and actual temperatures and a second demand based on the second set and actual temperatures, and is configured to switch the valve to the first and second positions based on comparison of the first and second demands. A method for controlling a heating installation heats the first or second object based on such a comparison.