What is a ground source heat pump and how do they work?

If you’re looking to keep your energy bills lower while going greener, then you may be considering getting a ground source heat pump.

Finding the right energy tariff through an energy comparison is a smart way to keep your bills low, but so is picking the right way to heat your home. Energy efficient methods, such as ground source heat pumps, have drawn more attention of late. Not only can they save you money, but also protect the environment in the process.

In this guide we take a look at how ground source heat pumps work and how they can reduce your energy bills. We also look at subsidies available with the Boiler Upgrade Scheme. Or you can read about their cousins, air source heat pumps.

Another way to go green and cut your energy bills is with solar panels – also see how much do solar panels cost and are they worth it for full analysis. 

What is a ground source heat pump?

The idea is the ground source heat pump replaces your existing gas boiler, and uses the natural heat in the ground outside your property to heat your home and warm your hot water. 

As it’s making use of natural heat it’s more environmentally friendly, and can also mean reductions to your energy bills in the future.

They won’t be for everyone as you need land near your property suitable for digging trenches or drilling boreholes.

How do ground source heat pumps work?

Ground source heat pumps transfer heat from the ground outside your home into your home, through your central heating system.

Ground source heat pumps are sometimes called ground-to-water heat pumps, and involve a loop of pipe that goes around your garden or outside space, collecting that heat. That pipe can be buried in trenches or inserted into a borehole.

The pipes carry what’s called a thermal transfer fluid, and as it passes through the pipes it absorbs the heat from outside. That heat is then transferred to water through the pump, heating your radiators or being stored for your hot water needs.

Energy bills

How much do ground source heat pumps cost?

Getting a ground source heat pump isn’t cheap. The eventual cost will depend on how easy it is to install the pump in the first place, as well as whether you opt to have trenches or a borehole for the ground loop.

According to the Energy Saving Trust, if you go for the trenches option then the typical installation costs come to £28,000, rising to a whopping £57,000 if you go for a borehole.

It’s really important to get quotes from a range of different installers so that you have a better idea of what it will really cost.

Thankfully you can get some help from the government towards those installation costs. Its Boiler Upgrade Scheme offers households the chance to apply for a grant when upgrading their boiler to a more energy efficient option.

If you get a ground source heat pump installed, you can apply for a grant of £7,500. Grants are also available for those installing air source heat pumps or biomass boilers.

Can a ground source heat pump save me money?

Ground source heat pumps could mean you have lower energy bills. These pumps are powered by electricity, but they are really efficient ‒ for every unit of electricity being used by the pump, it will then generate additional units for heating your home.

Whether they will save you money though, and the size of any potential savings, will vary between households.

According to analysis from the Energy Saving Trust  in January 2024, those with new A-rated gas boilers would save an average of £105 a year through switching to a ground source heat pump (based on a well insulated four-bedroom detached home), but those with older heating appliances or use more energy will make bigger savings.

Here’s how they break down based on how you currently heat your home:

Existing heating system Potential annual saving through using a ground source heat pump
Old (G Rated) gas boiler £630
New (A Rated) gas boiler £105
Old electric storage heaters £2,300
New electric storage heaters £1,500
Old (G rated) oil boiler £950
New (A Rated) oil boiler £260
Old (G Rated) LPG boiler £920
New (A Rated) LPG boiler £300
Coal £2,000

Source: Energy Saving Trust

On top of those cash savings, you can reduce your carbon dioxide emissions by up to 12,000 kg per year with a ground source heat pump.

It’s important to bear in mind that the size of those savings will ultimately be driven by how you use your energy as much as the heating system you employ in your home.

And if you’re wondering will energy bills go down?, we’ve a round-up of the latest predictions of what will happen with the energy price cap. 

Other ways to tackle energy costs

To help with soaring energy costs, see if you can get support with your energy bills such as any hardship funds available. 

Plus it’s worth checking to see if you qualify for the Warm Home Discount, Cold Weather Payments and Winter Fuel Payments.

Also if you want to reduce your usage, check out our energy saving tips.

How much space do I need for a ground source heat pump?

If you want to get a ground source heat pump, you’ll need access to the ground outside your home.

Precisely how much space you need will vary based on the type of pump you’re looking to get, how big your home is and how much heat you will need to generate.

Typically these installations are classed as permitted developments and so won’t require planning permission. Do bear in mind though that your garden will likely need to be dug up, so if you have recently laid new grass or a new patio, it might not be right for you. 

Is a ground source heat pump suitable for my property?

Ground source heat pumps are not going to be an appropriate option for all property types.

These heat pumps produce heat at a lower temperature than conventional central heating systems. As a result they are going to be more effective in homes which distribute heat over a greater area, such as those with larger radiators or underfloor heating. And those homes that are generally better insulated. 

The Centre for Sustainable Energy points out that they are best for homes where there are gradual temperature demands, rather than sudden ones. In other words, they’re not going to be at their best if you try to crank up the heating quickly.

How long will a ground source heat pump last?

Ground source heat pumps are designed to be a long-term option. The pumps themselves last for around 15-20 years, while the pipes are expected to last around 70 years.

As a result you don’t need to worry about replacing pumps for a long time, while they shouldn’t require much in the way of upkeep.

That said, it’s important to regularly schedule maintenance, while the pump may need to be re-pressurised or have the quality of its thermal liquid checked every couple of years. And it’s worth understanding that right now, as they are still fairly new to the market, you may find it harder to find a local tradesman qualified to service it.

How is a ground source heat pump different from an air source heat pump?

Ground source heat pumps and air source heat pumps work in different ways, but both are designed to heat our homes in a more efficient way.

With an air source heat pump, heat is taken from the air outside the property, absorbed into a thermal fluid. As with a ground source heat pump, the liquid then runs through the heat pump and is used to heat the property or a hot water cylinder.

As air source heat pumps don’t involve the installation of underground pipes, they are cheaper to install ‒ according to the Energy Saving Trust they cost around £7,000 to £13,000 to put in place.

However, they may be less efficient than their ground source peers. The Energy Saving Trust points out that the colder the ‘source’ temperature that the pump has to work with, the harder the pump will have to work. Given air temperatures can drop below freezing, air source heat pumps may have to work harder, since the temperature below the ground never falls that low.

Keep your home warm for less