Ground Source Heat Pumps
Ground source heat pumps use pipes buried in the garden to extract heat from the ground. This is usually used to heat water for radiators, underfloor heating systems and hot water.

See how a ground source heat pump can work in your home

Beneath the surface, the ground stays at a constant temperature, so a ground source heat pump can be used throughout the year - even in the middle of winter.

How does a ground source heat pump work?
A ground source heat pump circulates a mixture of water and antifreeze around a loop of pipe - called a ground loop - which is buried in the garden. Heat from the ground is absorbed into this fluid and is pumped through a heat exchanger in the heat pump. Low grade heat is then extracted by the refrigeration system and, after passing through the het pump compressor, is concentrated into a higher temperature useful heat capable of heating water for the heating and hot water circuits of the house. Ground loop fluid, now cooler, passes back into the ground where it absorbs further energy from the ground in a continuous process while heating is required.
The length of the ground loop depends on the size of your home and the amount of heat you need - longer loops can draw more heat from the ground.
Normally the loop is laid flat, or coiled in trenches about two metres deep, but if there is not enough space in your garden you can install a vertical loop to a depth of up to 100 metres for a typical domestic home.
Heat pumps have some impact on the environment as they need electricity to run, but the heat they extract from the ground, air, or water is constantly being renewed naturally.
The efficiency of a ground source heat pump is measured by a coefficient of performance (CoP) - the amount of heat it produces compared to the amount of electricity needed to run it. A typical CoP for a ground source heat pump is around 3.2 if used with under floor heating (it can be reduced if used with radiators). This means for every unit of electricity used to power the pump, you could get 3.2 units of heat.

The benefits of ground source heat pumps

  • Reduce your CO2 emissions: on average a ground source heat pump could save around 540kg of carbon dioxide every year when replacing an oil boiler. Emissions can be reduced further if the heat pump is partly powered by another renewable technology, such as solar electricity (PV).
  • • No fuel deliveries required.
  • • Can provide space heating and hot water
  • • Can lower fuel bills, depending on what heating fuel you are replacing
  • It's often classed as a ‘fit and forget’ technology because it needs little maintenance.

Is a ground source heat pump suitable for my home?
To tell if a ground source heat pump is right for you, there are a few key questions to consider:

  • Is your garden suitable for a ground loop? It doesn't have to be particularly large, but the ground needs to be suitable for digging a trench or a borehole and accessible to digging machinery.
  • Is your home well insulated? Since ground source heat pumps produce a lower temperature heat than traditional boilers, it's essential that your home is insulated and draught proofed well for the heating system to be effective. It could also make the system cheaper and smaller.
  • What fuel will you be replacing? If you're replacing an electric, oil, Liquid Petroleum Gas (LPG) or coal heating system, a ground source heating system will pay for itself quite quickly. If you're replacing a new, more efficient heating system, your savings will be smaller.
  • What type of heating system will you use? Underfloor heating systems or low temperature fan convectors (warm air heating) will perform much better than radiator-based systems because of the lower water temperatures required.
  • Is the system intended for a new development? Combining the installation with other building work can reduce the cost of installing the system.
  • Costs and savings
    Costs of installing a typical system range from about £7,000 to £13,000. Running costs for a year, where all hot water and space heating can be provided by the system are likely to be around £650 per year, but will depend on a number of factors - including the size of your home and how well insulated it is.
    Savings - will vary depending on many factors, some are outlined below. It is important that the system is controlled appropriately for your needs. Actual saving figures will depend on your exact fuel prices
  • The heat distribution system: underfloor heating often provides greater efficiencies than radiators because the water doesn’t need to be heated to such a high temperature.
  • Fuel costs: you will still have to pay fuel bills with a heat pump because they are powered by electricity. The saving you achieve can be affected by the price of the fuel you are replacing and the price of the electricity for the heat pump.
  • Efficiency of old and new system: the efficiency of the old heating system will affect how much you spent on heating bills previously. If the old heating system was inefficient heating bills could have been high and the difference between the new running costs and the old running costs will be greater, therefore providing a greater saving.
  • If the system is providing hot water as well as space heating: the provision of hot water can lower system efficiencies, therefore making running costs higher.
  • Temperature setting: if you heat your home to much higher temperatures with a new heat pump system than you did with an old heating system then you will experience greater comfort benefits, but heating bills will be higher than if you continued with the same heating pattern. It’s a good idea to set thermostats to around 18 to 21 degrees centigrade.
  • Using the controls: learn how to control the system so you can get the most out of it.

To reduce your home's CO2 emissions further, consider installing solar electricity or some other form of renewable electricity generating system to partly power the compressor and pump. Or consider using solar hot water to provide low carbon hot water in the summer months.
The savings below assume a ground source heat pump has been installed in a detached property and it provides 100% of space heating and up to 50% of domestic hot water, the additional 50% is met through an electric heater. The figures assume radiators are being used as the distribution system rather than under floor heating, which has reduced the season efficiency of the system.

Fuel Displaced

£ Saving per year

CO2 saving per year

Gas

£190

No saving

Electricity

£840

6 tonnes

Oil

£160

540kg

Solid

£600

5.6 tonnes

To find out how much you could potentially save by installing a heat pump Call CLK today!