A ground source heat pump takes heat from the ground and uses it to heat your home.
It runs on electricity. However, much of the heat comes from the ground.
This means it can provide more heat energy than the electricity it uses.
So, it works differently from a gas boiler or standard electric heater.
How Does It Work?
A ground source heat pump uses pipes buried outside your home.
A fluid flows through these pipes and collects heat from the ground.
The heat pump then raises the temperature of this heat and sends it to your heating system.
In simple terms:
Ground → Buried pipes → Heat pump → Heating → Home
The system can normally provide heating and hot water.
Where Does the Heat Come From?
The ground stores heat from its surroundings.
Below the surface, the temperature is usually more stable than the air above it.
So, a ground source heat pump has access to a fairly steady source of heat throughout the year.
However, the system still needs to be the right size for your home.
What Are Ground Loops?
The pipes buried in the ground are called ground loops.
A mixture of water and antifreeze usually flows through them.
As the fluid moves through the pipes, it collects heat from the ground.
It then carries this heat back to the heat pump.
The heat pump takes the heat from the fluid. Then, the fluid travels through the ground loops again.
This process keeps repeating.
How Are the Pipes Installed?
There are two main ways to install ground loops.
Horizontal Ground Loops
Long pipes can be buried in trenches.
This needs a suitable area of land around the property.
So, it may work well if you have a large garden or other available land.
However, installing the pipes means digging up the ground.
Boreholes
Another option is to drill deep holes into the ground.
The pipes are then installed vertically.
Boreholes need much less surface area than horizontal ground loops.
However, drilling can be expensive.
So, the best option depends on your property, available land and ground conditions.
How Much Land Do You Need?
There is no simple answer.
The amount of land needed depends on:
- how much heat your home needs
- the ground conditions
- the ground-loop design
- the space available
- how the pipes will be installed
So, don’t rely on a general rule about how much pipe or land you need.
The system should be properly designed for your property.
Does the Ground Get Cold?
Yes. The ground around the pipes becomes cooler as heat is taken from it.
However, heat also moves back into the ground from the surrounding area.
So, a well-designed system should allow the ground to recover.
This is why the ground loops need to be the right size.
If too much heat is taken from too small an area, the system may not work as well.
How Does It Heat Your Home?
The heat pump heats water for your heating system.
This warm water can then flow through:
- radiators
- underfloor heating
Heat pumps often use lower water temperatures than traditional boilers.
So, your radiators or underfloor heating need to provide enough heat at these lower temperatures.
Some homes may need larger radiators.
However, others may already have suitable ones.
Will I Need New Radiators?
Not necessarily.
First, the installer should work out how much heat each room needs.
Then, your existing radiators can be checked.
Some may already be large enough.
Others may need replacing with larger ones.
Underfloor heating can also work well with heat pumps. This is because it spreads heat over a large area and can work at lower water temperatures.
Learn more: Insulation and Heat Loss →
Does My Home Need Insulation?
Your home does not need to be perfectly insulated to use a ground source heat pump.
However, reducing heat loss can make any home easier to heat.
For example, loft insulation and draught proofing may reduce the amount of heating you need.
This could also affect the size of heat pump required.
So, look at your home as a whole rather than thinking about the heat pump on its own.
Learn more: Insulation and Heat Loss →
What Is COP?
You may see COP when looking at heat pumps.
COP means Coefficient of Performance.
It compares the heat supplied with the electricity used.
For example:
1 kWh of electricity → 4 kWh of heat
This would give a COP of:
4
However, a heat pump will not always achieve the same COP.
Its performance changes depending on how the system is working.
So, don’t treat one COP figure as its performance all year.
What Is SCOP?
You may also see SCOP.
This means Seasonal Coefficient of Performance.
SCOP looks at performance across a heating season.
So, it can give you a better idea of how much electricity the heat pump may use over a longer period.
However, it is still an estimate.
Actual performance will depend on your home, heating system and how you use it.
Why Can Ground Source Heat Pumps Perform Well?
The temperature below the ground is usually more stable than the outside air.
This can help a ground source heat pump work efficiently throughout the year.
However, this does not automatically mean ground source is better than air source.
Ground source systems usually need much more installation work.
So, you need to consider both performance and installation cost.
Can It Heat Hot Water?
Yes.
A ground source heat pump can normally provide hot water as well as heating your home.
However, you will usually need a hot-water cylinder.
So, make sure you have enough indoor space for the equipment.
Some systems may also use an immersion heater when needed.
Learn more: Your Hot Water System →
How Much Electricity Will It Use?
This mainly depends on:
- how much heat your home needs
- how well the heat pump performs
For example, suppose your home needs:
12,000 kWh of heat a year
If the heat pump provides an average of four units of heat for every unit of electricity, the simple calculation would be:
12,000 ÷ 4 = 3,000 kWh of electricity
This is only an example.
Your actual electricity use will depend on your home, hot-water use, weather and system performance.
Will It Reduce My Bills?
It might. However, lower bills are not guaranteed.
Running costs depend on:
- how much heat your home needs
- how well the heat pump performs
- electricity prices
- what fuel you currently use
- how efficient your current heating is
- how well the new system is designed
- how you use your heating
Ground source heat pumps can also be expensive to install.
So, compare both the installation cost and the expected running cost.
Don’t judge the system only by its efficiency figure.
Ground or Air Source?
Ground source and air source heat pumps both use electricity to move heat.
However, they collect that heat from different places.
Air source → takes heat from the outside air
Ground source → takes heat from the ground
Air source heat pumps are usually easier to install. They don’t need long trenches or boreholes.
Ground source heat pumps can benefit from more stable ground temperatures. However, installation is usually more difficult and expensive.
So, the best choice depends on your property.
Learn more: Air Source Heat Pumps →
What About Maintenance?
The buried ground loops can last a long time when they are properly installed.
However, the heat pump and other parts of the heating system still need looking after.
Before buying, ask:
- What maintenance will it need?
- How often will it need servicing?
- What does the warranty cover?
- How long should each part last?
- What might need replacing in the future?
This will give you a better idea of the long-term cost.
Before You Buy
Start by finding out how much heat your home needs.
Then, check whether you have enough suitable land for ground loops or whether boreholes are possible.
Next, ask how the system has been designed.
Also check:
- expected yearly electricity use
- expected seasonal performance
- ground-loop or borehole design
- radiator sizes
- hot-water arrangements
- indoor space needed
- installation work
- total installation cost
- warranty
- servicing needs
Ask for an estimate of the running cost too.
Most importantly, ask what assumptions have been used to calculate it.
Don’t choose a system simply because it has a high efficiency figure.
The whole system needs to suit your home.
What About Grants?
Government support for heat pumps can change.
So, check what help is currently available before making a decision.
Check current heat-pump grants and support →
Key Points
- A ground source heat pump takes heat from the ground and moves it into your home.
- It uses electricity, but much of the heat comes from the ground.
- Buried pipes collect the heat. These can be installed in trenches or boreholes.
- Ground temperatures are fairly stable, which can help the heat pump perform well throughout the year.
- Ground loops need to be properly designed and sized.
- You need suitable land or access for boreholes. This can make installation difficult and expensive.
- The whole heating system matters. Radiators, underfloor heating, water temperature and controls all need to work well together.
- You may not need new radiators. Check how much heat each room needs first.
- Reducing heat loss can help. Better insulation and draught proofing can make your home easier to heat.
- COP and SCOP can help you compare performance, but they do not tell you exactly how the system will perform in your home.
- Ground source heat pumps can normally provide heating and hot water. You will usually need a hot-water cylinder.
- Running costs depend on several things, including heat demand, system performance and electricity prices.
- Compare the installation cost as well as the running cost.
- Ask about maintenance, warranties and future replacement costs.
- Check current grants and support before making a decision.
- Most importantly, choose a system designed around your home, its heat loss and the available ground.
Important Information
Energility provides general information to help you understand energy, household and business costs, services and ways to save money. It is not financial, legal, tax, technical or professional advice.
Prices, tariffs, grants, government schemes, regulations and other information can change. Costs, savings and calculator results are estimates and your actual results may be different.
Before making an important financial decision, signing a contract or carrying out significant work, check the latest information and consider getting advice from a suitably qualified professional where needed.
Energility may receive a commission or other benefit from some links or services. Where this applies, we aim to make it clear. This does not increase the price you pay unless stated otherwise.
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