Heat pumps are an increasingly popular way to heat homes in the UK. Instead of burning gas, wood, or electricity to heat a home, heat pumps absorb heat from the surrounding area, transferring it into your home. Because they only use a fraction of the electricity, they’re much less expensive (and more environmentally friendly) than conventional heating systems.
What most people don’t realise is that there are two types of heat pumps: air source and ground source heat pumps. Both these devices can be around 300-400% more efficient than gas boilers under typical conditions. However, there are a few key differences.
We’ll cover what an air source or ground source heat pump is, how much they cost, what the main differences are, and which one is right for you.
What is an Air Source Heat Pump?
An air source heat pump (ASHP) is like a reverse air conditioner. It pulls the heat from the outside air and channels it into your home. A fan pulls in the air, running alongside a special liquid called a refrigerant. This liquid absorbs the heat, turning it into a gas. The gas is then compressed and passed into your home’s heating system.
Pros
- Very efficient – you get a lot more heat out than the electricity you put in.
- Greener heating option as it cuts carbon emissions compared to gas or oil
- Can reduce energy bills over the long run
Cons
- Costs more to install upfront compared to standard heating systems
- Works best in a well-insulated home
- Heats more gently than a gas boiler, so radiators sometimes need upgrading
What is a Ground Source Heat Pump?
A ground source heat pump (GSHP) works similarly to its air source counterpart. The difference (as you might have guessed) is that instead of pulling heat from the air, it relies on the ground.
Often, pipes are buried underground, either in trenches or boreholes. They’re filled with a mixture known as “brine” (a combination of water and antifreeze). This mixture pulls heat from the ground into the heat pump, transfers it to the refrigerant, which is then compressed and sent into your home.
Pros
- Very stable efficiency – the ground stays at a steady temperature year-round
- Lower running costs than most heating systems over time
- Long lifespan once installed, with minimal wear and tear
Cons
- High installation cost compared to air source systems
- Requires land or drilling which isn’t practical for every property
- More disruptive installation, especially for existing homes
Heat Pump Installation Costs and Practical Considerations
The big hesitation most people have around heat pumps is the cost. After all, installation can involve a complete overhaul of your property’s heating system. The most common factors influencing the cost of both heat pumps include:
- The size and layout of your property
- Whether the home is newly built or existing
- The level of preparatory work involved, including possible electrical upgrades
- Whether radiator upgrades are advised to maximise efficiency
Ground source heat pumps are the more expensive option. The additional work of digging trenches or boreholes inflates the price. On average, you can typically expect to spend around £11,000 for an air source heat pump and around £29,000 for a ground source heat pump. The Boiler Upgrade Scheme provides funding for both systems in England and Wales. You can receive £7,500 off the cost.
As well as the £7,500 Government grant, air source heat pumps are currently VAT free.
However, many new build homes are being built with ground source heat pumps from the start, this is a great thing to look out for when viewing properties. Buying a home with a ground source heat pump already installed will mean cheaper heating bills.
The other consideration is space. If you don’t have outdoor space available, a ground source heat pump isn’t possible as it involves trenches and boreholes for pipework. Without the space, there’s nowhere from which to draw heat.
You’ll also want to consider how long it takes to install an air source heat pump.
Energy Efficiency and Running Costs
Heat pumps depend on the surrounding temperature of your property. The colder the temperature of the ground or air (the “source” temperature), the harder the heat pump must work.
In the UK, air temperatures fluctuate between -5°C and 25°C for most of the year. That is an effective temperature range for air source heat pumps, although they struggle at extremes of temperature.
Ground source heat pumps pull heat from the soil. While it rarely drops below freezing, it never reaches the same heights as the air temperature. That means it’s generally less efficient throughout the warmest parts of the year. However, when the weather is coldest, GSHPs are more efficient than ASHPs.
In general, GSHPs are more efficient across the year as a whole. But it really depends on your location and specific setup.
Maintenance Requirements for Heat Pumps
Maintenance is another important factor because ASHPs require regular servicing to stay active. Ground Source Heat Pumps, on the other hand, are generally less intensive, needing less maintenance and monitoring. However, it’s still sensible to monitor ground loops occasionally to ensure there are no leaks or inefficiencies.
Environmental Impact and Sustainability
The most obvious benefit of heat pumps is the reduced carbon footprint, as heat pumps don’t rely on fossil fuels once they’re installed. In fact, the government Boiler Upgrade Scheme is designed to support the decarbonisation of heat in buildings.
Look into other renewable energy incentives and government grants (including local authorities) to save even more money on their installation.
Which Heat Pump is Right For Your Home?
There is no right answer.
If you don’t have the land or space for a ground source heat pump, then it’s pretty simple. You’ve got to go with an air source heat pump. But if you can afford the upfront costs and have the space, ground source heat pumps are more efficient, have lower running costs, and low CO2 emissions.
But ASHPs are much simpler to install. Even with the additional costs compared to GSHPs, they’re still better than a gas boiler.
Verdict: Air Source vs. Ground Source Heat Pump
Both systems have clear strengths. Air source heat pumps are simpler to install, work well for most homes, and cut CO2 emissions compared to gas boilers. Ground source heat pumps are more expensive and disruptive to install, but provide long-term, efficient, and very stable performance.
The right choice comes down to your property, your land, your insulation levels, and how much upfront investment you’re comfortable with. There’s no universal answer, and that’s why proper advice matters.
Considering installing a heat pump? Premium Heating Plumbing & Cooling specialises in professional heat pump installations. We can advise you on the best option for your property and budget.
Learn more about the options and get a personalised assessment for your home.