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Ground source heat pumps explained

Ground source heat pumps - trial results

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Ground source heat pumps - trial results

Find out what you can expect from a ground source heat pump, including top tips from experts and a trial of 54 different ground source pumps.

In order to investigate how well air source heat pumps and ground source heat pumps perform, the Energy Saving Trust ran a trial on 83 different heat pumps installed in the UK.

The Energy Saving Trust (EST) monitored 54 ground source heat pumps and 29 air source heat pumps in UK properties over a 12-month period from 2008 to 2009. The trial enabled the EST to identify which factors affect how well a heat pump works, and to better understand how households are actually using heat pump technology. 

You can use the results of the Energy Saving Trust's trial to help you decide whether a heat pump is right for your home.

Whether or not you get a ground source heat pump, it's worth making sure you're on the cheapest energy deal for you. You can use our independent switching site, Which? Switch, to compare gas and electricity prices.

Heat pump trial – key findings

The trials found that, correctly installed and operated, heat pumps can perform to a very high standard in UK homes. During the trial, the EST measured the the amount of heat the pump produces compared with the amount of electricity needed to run the system. This is known as the Seasonal Performance Factor (SPF). 

The average SPF for an air source heat pump was found to be 2.45 and for ground source heat pumps it was 2.82.

Many systems appeared to be installed incorrectly, and control systems were generally complicated. Phase one of the trial came to the following conclusions:

  • Design and installation There was a big variation in performance, with several early heat pumps incorrectly designed or installed.
  • Simplicity The best heat pumps tended to be the simplest in design and scope.
  • Hot water It's unclear whether using a ground source heat pump to also produce hot water impacts overall efficiency.
  • Heating controls The EST described an overall 'failure to explain proper control requirements' to heat pump customers, with many unsure how to properly use the controls to work their system.
  • After-care The installation company should be required to provide quality after-sales services.

What to expect from a heat pump-powered system

  • Your home may take longer to heat up.
  • If you're using radiators, expect them to feel warm rather than hot – heat pumps produce lower temperatures than a boiler. Heat pumps are better suited to underfloor heating.
  • You'll probably need to have your heat pump on for more hours a day than you would with a boiler.
  • You might need a separate electric heater to help provide all your heating and hot water needs.
  • The heating controls that come with a heat pump can be complicated – insist on easy-to-use controls and a demo from the installer.
  • Check the credentials of the ground source heat pump installer you're using – they should be accredited by the Microgeneration Certification Scheme, be able to design a system specifically suited to your property and offer an after-care service.

See our guides on solar panels and air source heat pumps to understand more about how they work.