Air source heat pumps work by  extracting heat from the outside air and using it to warm your home. They do this through a refrigeration process involving an evaporator, compressor and condenser. While they may seem like complex systems, their mechanics are actually quite simple. They are in fact very similar to air conditioning units. 

The evaporator collects the heat from the surrounding air and turns it into a gas. The gas is then compressed by the compressor, which increases its temperature significantly. This hot gas is then passed through a condenser where the heat is transferred to water or air within your home’s heating system. Once the heat has been transferred, the gas returns to its liquid state and repeats the cycle again. 

This process is highly efficient, as it only requires a small amount of electricity to run the compressor and fan.