Air Source Heat Pumps

What is an air source heat pump?

Air source heat pumps are a low-carbon heat technology. Put simply, they absorb ambient heat from the outside air in the same way that refrigerators extract heat from the inside, but in reverse, to heat your home and provide hot water. Heat pump systems are a proven and reliable technology developed primarily in Sweden, where most new houses have heat pump systems. Air source heat pumps are able to extract heat from the air even when temperatures are as low as -15° C. They look similar to air conditioning units and usually sit outside the property adjacent to a side or back wall.

Alternative to Conventional Heating Systems

Air source heat pumps are an alternative to conventional electric or gas central heating systems and can be used to heat radiators, underfloor heating systems, warm air convectors and hot water in your home. Heat pump systems produce a lower heat than a conventional boiler over a longer period of time, so work best with larger radiators or underfloor heating to achieve a similar temperature. Heat pumps require electricity to run but the heat source is renewable. Swapping to an air source heat pump could reduce your carbon footprint and lower your fuel bills, particularly if you’re replacing conventional electric or oil fuelled heating. Another benefit of heat pump systems is that they require little maintenance.

There are two types of air source heat pumps: air-to-water and air-to-air systems. Air-to-water heat pump systems transfer heat from the pump into your wet central heating system, i.e. your underfloor heating or radiators. Air-to-air systems produce warm air that is circulated around your home by fans. The later system is not able to provide hot water but can often be reversed in summer to provide cool air.

How do air source heat pumps work?

As mentioned above, air source heat pumps work similarly to fridges. Brine runs through collector coils in the outdoor heat pump system which absorbs heat from the air. This tepid brine meets refrigerant in the heat exchanger and causes that refrigerant to evaporate. The refrigerant is compressed by a compressor and the heat generated is transferred via a condenser into the property’s heating system. The refrigerant continues to circulate within the system and passes through an expansion valve to cool the temperature down to start the cycle again.