What is an air source heat pump?

An air source heat pump is a piece of heating equipment belonging to the family of aerothermal heat pumps (AHPs). Air-source heat pumps draw heat from the ambient air, unlike ground-source heat pumps which draw heat from the ground or water. The operation of an air source heat pump is relatively simple: a refrigerant, in liquid form and then in gaseous form, circulates in the circuit of the heat pump and recovers the heat calories contained in the air, outside or inside your home. The mechanism of the air source heat pump then increases the temperature of the fluid in the form of high-pressure vapor. This heat is recovered to be diffused and used to heat your home.

How the air source heat pump works

The transformation of calories from the ambient air into hot air is made possible by using a refrigerant. This transformation is broken down into four phases:

The refrigerant, in its liquid state, recovers the calories from the ambient air. Thanks to the energy captured, the temperature of the fluid increases, and it is then transformed into a gas and evaporates;

The compressor, powered by an electric motor, sucks in and compresses the refrigerant, which is gaseous, hot, and under high pressure.

The condensation of the refrigerant under high pressure allows the heat to be transferred to the indoor air. The gas returns to a liquid state.

The expansion valve reduces the pressure of the refrigerant and prepares the liquid fluid for the evaporation phase.

How is the heat diffused with an air source heat pump?

To distribute the heat, it is necessary to install fan coil units. These electrically powered heaters can be wall-mounted like traditional radiators, but they can also be built into the ceiling or wall. The warm air flows through the rooms via a network of air ducts and is distributed by the fan coil units. Alternatively, you can opt for a centralized diffuser, installed in a boiler room or laundry room, which conducts the warm air through insulated ducts to grilles placed in the different rooms of your house.

A heating system that depends on the weather

air source heat pumps are recommended in regions with a temperate climate, where temperature variations are not too great. This makes the heating system comfortable and economical. In regions with harsh winters, however, the performance of air source heat pumps is greatly reduced. The outside temperature plays a decisive role in the coefficient of performance (COP) of air source heat pumps.

The indispensable contribution of auxiliary heating with an air source heat pump

It is often necessary to keep a supplementary heating system in place to avoid running out of heat in very cold weather. Indeed, while the majority of air source heat pumps see their performance plummet when temperatures fall below zero, some models stop working altogether. The presence of a back-up heater is therefore essential.

Reversible heat pumps

Many air source heat pumps are reversible and have a function that allows them to reverse their system to draw heat from inside your home and release it outside. This means that your equipment can also be used as an air conditioner in the summer.