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Ground Source

  1.  What are Ground Source Heat pumps?
  2. How does it work?
  3. What are the benefits?
  4. Grants
  5. Frequently Asked Questions

Sol2o offer consultation, design, installation and maintainance of Air Source Heat Pumps.

 For an Air Source Heat Pump evaluation or a complete energy performance assessment of your property call us now on 0800 2800 020, or click here to register with us.

What are Ground Source Heat pumps?

Ground Source heat pumps are a proven and well-developed technology, which has been around for over 50 years utilising heat that is stored in the ground for heating purposes.

The earth has a natural ability to absorb and store heat directly from the sun, rain and the air as well as heat from within the earth itself. This low-grade heat can be extracted from the ground and transformed into temperatures that are high enough to heat hot water, homes and commercial buildings. It also has the ability to transfer to cooling in the summer providing the perfect temperature all year round.

How does it work?

In the UK we can have some cold winters with temperatures dropping as low as -5°C. However just a few meters under the earth surface, the ground actually remains relatively constant averaging between 8-10°C.

Ground source heat pumps use pipes buried in the garden to extract heat from the ground. A ground Source heat pump consists of three main components:

Ground Collector

There is a loop, which is buried beside the property and is invisible after installation. A fluid, which is a mix of water and anti freeze is circulated through the loop, absorbs heat energy from the ground. This is then pumped through the loop to the heat pump.

There are 3 types of collector:
Horizontal closed ground loop - This is the most cost effective option available with polyethylene pipe laid in trenches typically 1m below the earth's surface.

Vertical closed ground loop - This is predominantly used when space is at a premium. A borehole is drilled to the depth of 60-150 metres, with the collector fed into the hole.

Water Source - If ground water is available, such as a pond it can be utilised as a heat source and removes the need to drill or dig trenches.

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.

Heat Pump

The heat is transferred from a liquid to a refrigerant via a heat exchanger (evaporator). This refrigerant has a low boiling point normally, 100°C and as it absorbs this heat it evaporates into a gaseous state. This gaseous refrigerant is then increased in pressure by a compressor; this means there is a significant increase in temperature. The gas is then passed to a condenser where it is cooled and condensed as the expansion valve allows the pressure to drop. It is here that the heat energy is transferred from the refrigerant into the heating system.

Heating System

They gain maximum benefit and efficiency used to warm water for radiators or under floor heating systems. It can also be used to pre-heat water before it goes into a more conventional boiler via a modern high efficiency indirect water cylinder. They use only a small amount of electricity to circulate and compress fluid with an electric pump.

What are the benefits?

Save up to 50% on your fuel bills

With a properly sized and installed geothermal heating system you can seriously cut your heat bills. There are extremely cost effective where mains gas is not available. They have the potential to save you up to 540kg of CO2 per year when replacing an oil boiler, which is twice as expensive to run. Ground source heat pumps run on electricity, so there's no need to pay for gas, oil or solid fuels to heat your home.

Improved Energy efficiency

Unlike traditional boilers that create heat through the combustion of fossil fuels modern ground source heat pumps are extremely efficient. Heat pump systems are 3-5 times more efficient than fossil fuel boilers.

Reduced impact on the environment

Heat pumps can approximately reduce carbon emissions by as much as 50% compared to a gas central heating system.

Lower maintenance and servicing costs

The technology inside a heat pump works on similar principles to that of a domestic fridge. Therefore there is no need for regular servicing or annual safety checks unlike fossil fuel systems and the maintenance is minimal.


Sol2o can offer advice on appropriate grants available to you and help you in the application process. For more information regarding grants for renewable technologies please click here.

Frequently Asked Questions

Does the Ground Source Heat Pump work all year round?

Yes this system provides heating and hot water 365 days a year.

How long do the Ground Source Heat Pump units last?

Typically each Ground Source Heat Pump unit will last around 25 years. This includes the actual pump and the pipe, which is buried in the ground. The pipe is impervious to corrosion and tree roots.

How much annual maintenance is required on a Ground Source Heat Pump?

No annual maintenance is required.

How much space do I need for my Ground Source Heat Pump?

The heat pump unit has the same footprint of a dishwasher and stand between 1.4m to 1.8m and will fit in any model dwelling which has been constructed to UK standards (ceiling height is 2.3m) Space of 300mm should be allowed to one side of the unit to connect the ground loops.

What is suitable for a Ground Source Heat Pump installation?

Ground source heat pump installations are suitable for all new build and renovated buildings ranging from small houses, flats, apartment to schools and offices and spaces where heating and hot water are required. Where land area is restricted for the loop installation a ground source heat pump may not be suitable. An alternative would be either boreholes (which can be expensive) or an Air Source heat pump.

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