Heat water for your home with pipes buried in the garden

Ground source heat pumps use pipes buried in the garden to extract heat from
the ground. This is usually used to warm water for radiators or underfloor heating systems. It can also be used to pre-heat water before it goes into a more conventional boiler.

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 do ground source heat
  pumps work?
• The benefits of ground
  source heat pumps.
• Is a ground source heat
  pump suitable for my home?
• Costs and savings
• Air and water source heat
  pumps
• Find out more

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.
When the liquid travels around the loop it absorbs heat from the ground – used
to heat radiators, underfloor heating systems and
even hot water.

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.

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 without any reductions for the type of distribution system.

Ground source heat pumps

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.

• Eliminate your fuel
  bills: ground source heat pumps run on electricity, so there’s no
  need to pay for gas, oil or solid fuels to heat your home.

• Cut down on wasted
  electricity: heating your home with a ground source heat pump is
  much more efficient than using electric radiators.

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 do you want? Underfloor
  heating systems or warm air heating will work much better than
  radiator-based systems.

• 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 can be considerable – up to 540kg of CO2 and £160
if you’re replacing an oil-fired central heating system.

To reduce your home’s CO2 emissions further, consider installing solar
electricity or some other form of renewable electricity generating system to
power the compressor and pump.

Savings above assume ground source heat pump installed in a detached
property which provides 100% of space heating and up to 50% of domestic hot water,
the additional 50% is met through an electric heater.

Air and water source heat pumps
These systems use similar principles to ground source heat pumps to extract
heat from air or water instead of the ground.

Air source heat pumps can be fitted outside a house or in the roof space and
generally perform better at slightly warmer air temperatures. Water source heat
pumps can be used to provide heating in homes near to rivers, streams and
lakes.