An under-the-radar renewable energy solution, air-source heat pumps (ASHPs) have seen rapid growth over recent years- but they still trail far behind gas boilers in terms of installations.
How do air-source heat pumps work?
In this series, weโll be exploring how air-source heat pumps operate, their technology and why theyโre a popular choice for sustainable heating and cooling.
What is an air-source heat pump?
Air-source heat pumps (ASHP) are highly efficient systems that heat buildings by transferring thermal energy between the indoor environment and the outside air.
How do they do this?
Hereโs a basic breakdown of how air-source heat pumps heat your home:
Step 1: Air is drawn from the outside
The air-source heat pumpโs outdoor unit contains a heat exchanger coil and fan that pulls in the outside air. A cold refrigerant liquid then flows through the coil. This refrigerant has a very low boiling point, allowing it to absorb heat and convert into warm, low-pressure gas.
Did you know? Heating accounts for 30% of UK carbon emissions, and ASHPs offer a low-carbon alternative to gas boilers.
Step 2: Compressor increases temperature
The warmed refrigerant gas is pulled into a compressor, increasing the pressure of the gas and significantly increasing the temperature. The hot, high-pressure gas carries usable heat that can be transferred to your homeโs heating system.
Did you know? Even in cold weather, ASHPs extract heat from the outside air, working efficiently in temperatures as low as -15ยฐC.
Step 3: Heat is transferred to your home
The hot gas presses through a second heat exchanger in the indoor unit of the heat pump and transfers the refrigerant gas to either air or water. As the refrigerant releases its heat, it cools down and condenses back into a high-pressure liquid.
Did you know? When replacing a gas or oil boiler, air-source heat pumps can reduce a homeโs carbon emissions by up to 70%, especially when powered by renewable electricity.
Step 4: Refrigerant cools and condenses
After releasing its heat, the refrigerant passes through an expansion valve. The valve reduces the pressure of the refrigerant, which causes a drop in temperature. The refrigerant then returns to its original low-pressure, cold liquid state, ready to absorb more heat from the outside air.
Did you know? Under the boiler upgrade scheme (BUS) in England and Wales, eligible households can receive up to ยฃ7,500 to help with the installation cost of an air-source heat pump. If youโre interested in finding out how much you could save when you install an air-source heat pump, contact our team today!
