Air Source Heat Pumps

How do ASHPs work?
People often say it’s just like a fridge in reverse, which is true but not really a good explanation. The ASHPs consists of a closed loop of pipe which contains a refrigerant liquid. Inside the house the refrigerant is compressed to a high temperature and heat flows from the refrigerant into the house, outside the refrigerant is expanded and heat flows from the outside air into the refrigerant. A metaphor that I often use is

….. imagine you squeeze a sponge then go outside the house and release it and soak up some heat from the air --- then you go indoors and squeeze the sponge and the heat is released into the house …..

How much do ASHPs cost?

What ASHP shall I use?
All new houses require a SAP calculation in order to produce the mandatory Energy Performance Certificate (EPC). The output of the SAP calculation will give guidance on what ASHP to use.

So we can enter various ASHPs from the PCDB into the SAP calculation and see which make and model gives the best Plant Size Ratio and optimum efficiency. This information can then be passed to your heating engineer.

A typical house requires an ASHP of about 4Kw – 6Kw which should deliver a Space Heating Efficiency between 300% – 400%

What does an ASHP consist of?

What sort of heating does an ASHP provide?

What are ASHPs like to use?
This is often referred to as the 'end user experience'. People living in a house with an ASHP will not notice much difference than living in a house with conventional gas or oil systems. If the house feels a bit cold you merely turn up the thermostat, although it will take slightly longer to heat up than a house with conventional radiators. If you want hot water for a bath you simply turn on the taps, although if many people decide to use large volumes of hot water at the same time you run the risk of running out. However with a well-designed installation this should not happen.


If you would like more information, advice or a quotation, then please call

Richard Owen on 01485 544757 or click here for contact information  >>>    Contact Us