Tell Me More About Air Source Heat Pumps

We've recently added Air Source Heat Pumps (ASHP) to our thermal energy portfolio and this post aims to explain in greater detail the way that they work and the installation process involved with them. If you have any more questions, then please do leave us a comment below, contact us on Twitter or do the old fashioned thing and ring us up on 0800 157 7340!

How does an Air Source Heat Pump work?

Every air source heat pump has four main parts:

Evaporator;

Compressor;

Condenser (heat exchanger);

Expansion device.

(1) The evaporator collects heat from the outside air, which is then drawn into the unit by the fan through the evaporator fins and expelled through the front grille. The evaporator has liquid refrigerant passing through it, which is at a considerably lower temperature than the outside air, therefore the air gives up its heat to the refrigerant, which then vaporises.

(2) This preheated vapour now travels to the compressor where it is compressed and upgraded to a much higher temperature.

(3) The hot vapour now enters the condenser where it is surrounded by water from the heating system. The heat is given up to the cooler water and the now cooler refrigerant returns to its former liquid state but still under high pressure from the compressor.

(4) This high pressure is then released by passing the liquid through the expansion device and from there it returns to the evaporator and the cycle starts again.

How is it installed?

The unit is relatively small and lightweight, it is designed to allow easy access to all internal components, easy to transport, so our team have no problem getting the unit into position. Our experienced and qualified installers fit the unit in an appropriate location on the outside of your building and join it to the existing or new plumbing system as required. The external system has a condensation pipe that we fit to the drainage system.

Two pipes come into the building from the externally mounted unit, these will typically be taken into a loft and then out to feed radiators or to the circuit of pipes for under floor heating. If you have an existing boiler this can be isolated and kept for back up or removed completely. An internal pump sits on the incoming pipework and a flow meter and filter sit on the return feed pipe. The system is filled with Glycol antifreeze that works down to -20 degrees C. Each system comes with a control unit and room thermostat.

Air Source Heat Pumps that feed radiators are most efficient if larger format low level heat radiators are installed. We install radiators designed to go with the Aeromax Plus pumps, we’d recommend fan assisted radiators which push heat around the building aiding the convection and increasing the benefit of the heat pump.

As mentioned - any questions, please do call.