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How Does a Heat Pump Work?

A heat pump uses solar heat energy stored in the ground, water or air. This is renewable and totally free! Energy usage is reduced to the electricity required to run the compressor and circulation pumps inside the heat pump which can mean considerable energy savings when compared to a traditional oil or LPG boiler or all-electric heating.

The 'low-grade', renewable heat energy in the ground, water or air needs to be harnessed, collected and delivered to the heat pump. There are a number of proven methods for doing this which vary dependent on energy source as well as building and site conditions.

The Heat Pump Refrigeration Cycle

Inside the heat pump a refrigeration cycle takes place which is dependent on the delivery of heat energy to make the refrigerant evaporate. The refrigerant changes from liquid to gas so that it can be pumped to the compressor where it is pressurised which increases the temperature exponentially. In understanding how a heat pump works it is important to highlight that the refrigerant has a very low boiling point, so the 'low-grade' heat even at low temperatures (as low as -20°C in the case of some outdoor air heat pumps) enables evaporation to take place.

Once through the compressor, the now hot refrigerant gas passes into a heat exchanger called the condenser where it transfers its heat into water which is then ready to be distributed around the building's heating system or used to heat tap water.

Having delivered its heat energy in the condenser, the refrigerant is cooler and once it passes through the expansion valve it loses its pressure and cools further, returning to a liquid state. This diagram helps to illustrate the heat pump refrigeration cycle and the temperature changes.

Heat Pump Refrigeration Cycle

 

To view how the temperature changes within the refrigeration cycle watch this animation. 

 

This video clip shows Rory Kerr of Ecoliving explaining how a heat pump works at a ground source heat pump demonstration day.

To find out whether a heat pump is appropriate for heating your property contact us today and arrange a free, no-obligation site survey or call us on 0845 302 3121.