Air Source Heat Pumps (ASHPs) are an excellent sustainable alternative to traditional fossil fuel heating systems. With their green credentials and high efficiency operation they will play a huge part in helping the UK achieve its net zero carbon emission targets. From 2025 all new homes will be banned from installing gas boilers, meaning the adoption of heat pumps will become a popular alternative.

Heat pumps work by extracting the natural warmth of the surrounding environment to provide heating and hot water to your home. There are two main types of heat pumps: Ground Source and Air Source. Each ones name simply describes where the heat pump takes its heat from.

An ASHP in principle works like a refrigerator in reverse, the process consists of three main parts; absorption, compression and condensing.


Heat is absorbed from the outside air by a refrigerant in the ASHP, this takes place in the evaporator with the refrigerant changing from a liquid to a gas in the process.


The refrigerant gas is now compressed to increase its temperature further, it is this heat that is used to warm up your hot water cylinder or heating system.


As the refrigerant transfers the heat into your homes heating system it gradually cools down and condenses back into a liquid. This occurs in a second heat exchanger, which cooler water from the central heating can continue to absorb the heat from the liquid refrigerant within this second exchanger, making the system very efficient.


Once the refrigerant has cooled right down, it passes through an expansion valve. In here, the liquid’s pressure is decreased and it returns to the evaporator to begin the whole cycle again.