Ground Source Heat Pumps

Welcome to a series of four short video clips designed to show what you can do in your home to produce electricity and/or hot water for your use.

The information and views provided are based on actual use by Chew Magna residents who have installed these technologies and have been using them for years.  This means you are getting actual operational experience and not just marketing views from the equipment supplier!

Some of the issues raised will be specific to the location and not associated directly with the technology and these will be highlighted.

Ground Source Heat Pumps

  • Heat pumps are being increasingly promoted as a source of gas/oil free heating and hot water.  There are two main types of heat pump, air-to-water heat pumps (GSHP) and air-to-air heat pumps (ASHP).  In this note we discuss GSHP in more detail.
  • Heat pumps work by capturing heat from outside and moving it into your home, using electricity to do so.  The quantity of heat delivered into your home is greater than the quantity of electricity used to power the system.  If the electricity used to power it is also renewable, then the heating and possibly also hot water, is carbon-free.
  • GSHP use two types of collection system, depending on the availability of land.  If sufficient land is available a ground loop system of buried plastic pipes is used, while if the available land area is limited, boreholes are used but are a much more expensive option.
  • In a GSHP the heat energy is gathered from a water/anti-freeze mix, called ‘brine’, circulating in underground pipes or in a borehole that is pumped to a heat exchanger inside the house.  The water mix passes through the heat exchanger, transferring the heat to the refrigerant, which continues its journey around the compressor circuit.  Look at a heat pump as a ‘reverse’ refrigerator, taking in heat from the ground and boosting it to provide heat.
  • The following figure shows the basic principle of how a heat pumps works.
  • A typical GSHP arrangement and the actual unit are shown in the following diagram and photo:
  • For people with gas boilers (not LPG or oil boilers) heat pumps are likely to be more expensive to run, unless attention is paid to ensuring maximum efficiency of the heat pump in the heating system by using best practice radiator/underfloor heating design.  For energy efficient, new build homes, with high standards of thermal insulation, as utility prices fluctuate over time it is expected heat pumps will become the cheapest, as well as the lowest carbon form of heating available.
  • Before installing a heat pump, it’s important to check if you need to apply to your local planning authority for permission.  Most heat pump installations are considered ‘permitted developments’, meaning no permission is required.  However, there are exceptions and it’s best to check with your local planning department before proceeding, especially if you live in a listed building or conservation area.
  • A number of factors affect how your energy bill will change, including:
  • fuel you are replacing and how much it costs;
  • electricity tariff;
  • current domestic RHI tariff for GSHP is 21.29p/kWh;
  • degree of insulation in your home’;
  • type of heat pump and its efficiency;
  • design of the central heating system;
  • your location and average air or ground temperatures throughout the year.
  • The cost of a ground source heat pump installation varies, influenced by:
  • Access to the ground and whether you choose trenches or a borehole to lay the ground loop;
  • Brand, model and size of heat pump chosen;
  • Size of the property and how much heat it needs;
  • Whether a newbuild or an existing property;
  • Whether you’re opting to make any improvements to your radiators to improve the efficiency of the heat pump, or if you are installing radiators or underfloor heating for the first time.
  • Typical costs are around £24,000 if your ground loop is in trenches but could be around £49,000 if you need boreholes.  It is recommended to speak to at least three installers to provide a quote for your heat pump system to give you the best idea of likely costs for your home.
  • For more information go to  or
  • PROS:

•    Energy efficient, low carbon heating;

•    Provides cooling and heating;

•    Constant and inexhaustible and virtually silent;

•    Eligible for grants of £6,000 off the cost and installation of a GSHP until 2025.

  • CONS:
    • Installation cost can be high, ranging between say £29,000 to £49,000, depending on whether you van use a ground loop system or need boreholes;
    • May incur costs beyond the initial installation, as to get the full benefits of a heat pump your home must be properly insulated, including cavity wall insulation, roof insulation and double glazing;
    • Disruptive installation, as having a heat pump system installed is a big job that will require having your garden dug up and you may need to have underfloor heating and new radiators installed too, which adds to the disruption;
    • If your home doesn’t have a reasonably sized outdoor space where the pipes can be buried, you cannot have a heat pump installed.  GSHP can be used in flats but all owners will have to agree to the expense and disruption that comes with having one fitted.
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