Planning to upgrade your heating system? Now is a smart time to explore heat pumps. With energy prices rising and new rules pushing for greener homes, more people are choosing low-carbon alternatives.
If you’re planning a heat pump installation, you’ve likely come across the air source vs. ground source debate. This guide breaks it down. We’ll cover costs, efficiency, installation, and how much space you need. By the end, you’ll have a clear idea of which one works best for your property.
Fast Facts for Homeowners:
- Heat pumps help reduce your carbon footprint and cut long-term energy costs.
- Air-source heat pumps cost between £8,000 and £18,000.
- Ground-source systems start from £14,500, reaching up to £45,000.
- Ground source models offer higher efficiency: 324% vs 265% for air source. (Source: Association for Decentralised Energy)
- If you’re installing a heat pump in your home, you could be eligible for the £7,500 Boiler Upgrade Scheme grant. (Learn more: Boiler Upgrade Scheme)
- Choosing between air and ground systems depends on space, budget, property type, and heating needs.
How Heat Pumps Work
Heat pumps operate a bit like a reverse fridge. Instead of pushing warm air out to stay cool, they pull heat in to warm your home. The system extracts low-grade heat from the environment, boosts it using a compressor, then circulates it through your radiators or underfloor heating.
Air-source heat pumps pull warmth from the outside air, even in winter. They use a fan to draw air over a refrigerant coil that captures and concentrates heat.
Ground-source thermal pumps collect heat from underground using a network of buried pipes. The soil stays at a steady temperature year-round, which gives these systems an efficiency edge.
How Your Property Affects Your Heat Pump Choice
Not all homes are built the same, and your property plays a big role in which heat pump is right for you. Factors like insulation, layout, garden access, and heating setup all influence what works best.
Let’s explore how different property types guide this decision.
New Builds vs. Existing homes
New builds are the ideal match for heat pump systems. They’re designed with energy efficiency in mind, often meeting high insulation standards. Because of this, these homes typically need smaller thermal pumps that run more efficiently.
The Future Homes Standard will make low-carbon heating a requirement in new builds from 2025, which is why many homeowners are already making the switch.
Older homes, like Victorian terraces or 1960s flats, can be more challenging. That said, the Electrification of Heat project proved heat pumps can work in nearly every type of UK home. These properties may benefit from basic upgrades like extra insulation, but major renovations aren’t always necessary.
Space Requirements for Each Systems
Here’s how air source and ground source systems compare when it comes to physical space:
| Feature | Air-source | Ground-source |
| Unit Size | 1–1.5m tall, 0.5–1m wide | Varies – some fit in cupboards, others are fridge-sized |
| Additional Space | Hot water cylinder if used: 80cm x 80cm cupboard space required | Larger footprint needed |
| Installation Space | Minimal outdoor space required (1–2m²) | Horizontal loops: 700–800m² land;
Vertical boreholes: 5–6m spacing, 50–150m deep |
If space is limited, air source systems are often the better fit.
Garden Access and Ground Conditions
Ground source systems need space for digging, drilling, and heavy equipment. You’ll need clear access for construction vehicles, and soil type also matters.
Wet or clay soils transfer heat better, improving efficiency. If you don’t have enough horizontal space, you can opt for vertical boreholes, although these are more expensive.
In contrast, air source systems avoid these complications. They’re ideal for properties with small gardens or those in built-up areas where trenching or drilling isn’t practical.
Not sure if your home is suitable? Get a free site assessment and see what’s possible.
Heat Pumps Case Studies: Smarter Heating in Action
Case Study 1: Air Source in a Compact Sutton Home
Property: 2-bedroom mid-terrace house in Sutton Coldfield
Challenge: Limited garden space and no room for ground works
System Chosen: Air source heat pump with hot water cylinder
The homeowner wanted to switch from a gas boiler to a low-carbon system but had very little outdoor space. Ground source was ruled out due to lack of access and budget. An air source heat pump was installed at the rear of the house, mounted on a wall just above ground level. A new hot water cylinder was fitted inside a kitchen cupboard.
Result:
- The system was fitted in just 2 days.
- Loft insulation was topped up to help boost efficiency.
- Heating bills dropped by around 20 percent in the first winter.
This case shows how even small homes can switch to clean heating without major renovations.
Case Study 2: Ground Source in a Spacious Detached Property
Property: 4-bedroom detached home in Erdington
Challenge: Long-term energy savings and low running costs
System Chosen: Ground source heat pump with horizontal ground loops
The family was planning to stay in their home for at least 15 years and wanted to reduce their carbon footprint. They had a large back garden, which made ground source a strong option. Horizontal loops were installed underground, and the pump was located in a utility room near the kitchen.
Result:
- The installation took 2 weeks, including trench work.
- The system delivers a Seasonal Performance Factor (SPF) of over 3.2.
- Energy bills have fallen by around 30 percent.
- Quiet, stable performance even in freezing temperatures.
This case highlights how ground source systems can offer better performance when the conditions are right.
What Heat Pump Installation Really Looks Like
Installer fitting a geothermal pump outside a house
Sales brochures make installation sound easy, but the reality can be more involved. Understanding the full process upfront allows you to prepare with confidence and minimise unexpected issues.
Let’s break down what actually happens when installers arrive at your home.
How Long It Takes to Install
Air source heat pumps are quicker to install. Most systems are fitted in 1 to 2 days, though installers often allow up to 5 days. This extra time covers integration with your existing heating system and leaves room for troubleshooting.
Ground source systems take longer. Simple installations might take 1 to 3 days, but more complex setups with boreholes or trenches can stretch to 2 or even 3 weeks.
How Much Disruption to Expect
Heat pump installation brings medium-level disruption to your home. It’s more involved than replacing a boiler. Multiple technicians will likely be on-site for several days.
You may lose hot water for a day during installation. However, good installers often fit a temporary fix, like an immersion heater, to keep things running.
Some of the most common homeowner concerns include:
- Replacing or upgrading pipework
- Changes to home interiors for fabric improvements
- General disruption across multiple rooms
Common Installation Issues
Installations can go wrong without proper planning. Here are some of the most frequent challenges:
- Oversized systems: A 2024 survey by Heatly found that more than half of thermal pumps were too large for the home, leading to poor performance and wasted energy.
- Inaccurate calculations: Around 35% of installers reported mismatches between design calculations and real-world heat loss.
- Poor positioning: Without good ventilation and proper layout, systems can underperform and cost more to run.
- Planning permission: Although many heat pump installations are now permitted without a formal application, homes in conservation areas or listed buildings may still require approval.
- Seasonal timing: Ground source systems benefit from groundwork done in spring or summer, when soil conditions are better.
How Heat Pumps Perform in Real-World Conditions
Heat pump operating in snowy conditions
Manufacturer specs are useful, but real performance shows up when the weather shifts. Let’s explore how air-source and ground-source heat pumps handle the demands of everyday life.
Winter Efficiency
Cold weather is the ultimate test for any heating system.
Ground source systems keep delivering reliable warmth all year. Why? Because the ground maintains a consistent temperature between 10 and 12 degrees Celsius, even in winter. This helps these systems achieve a Seasonal Performance Factor (SPF) of around 3.24. That means for every unit of electricity used, you get over three units of heat back.
Air source systems, on the other hand, work against falling outdoor temperatures. Their efficiency drops when the weather gets cold. With an average SPF of 2.65, they still perform well, but the gap becomes noticeable during freezing months.
Summer Cooling Capabilities
Both heat pump types can cool your home, not just heat it.
Ground source systems shine in this area thanks to the stable underground temperature. They cool efficiently and quietly, making them a year-round climate solution.
Air source systems use a reversing valve to flip the heating process. They pull heat out of your home and send it outdoors. Modern air source models with variable-speed compressors are highly efficient in summer.
A 2021 study from RMI found they used up to 18 percent less electricity than standard high-capacity air conditioning units while maintaining indoor comfort.
Want year-round comfort and lower bills? Discover what heat pump system fits your lifestyle and budget.
How Heat Pumps Work with Your Current Heating System
Before installing a thermal pump, it is important to understand how it will interact with what you already have. Heat pumps operate differently from traditional boilers and might require a few adjustments.
Lower Operating Temperatures
Heat pumps do not produce heat at the same high temperatures as gas or oil boilers. Instead, they work best with systems that spread warmth more evenly across your home.
- Underfloor heating is a perfect match. It runs at low temperatures and distributes warmth gradually, increasing efficiency.
- Radiators can still be used, but they may need to be larger or made from materials that hold and release heat efficiently.
- In some cases, your installer may recommend replacing old radiators to maintain comfort without driving up running costs.
Hot Water Systems and Compatibility
Most heat pumps require a hot water cylinder because they do not produce instant hot water like combi boilers. If your home does not already have one, this will be added during installation.
Make sure the cylinder is correctly sized to meet your household’s needs. Oversizing can waste energy, while undersizing can leave you short on hot water.
Electrical Supply Considerations
Heat pumps are energy-efficient systems that use electricity to heat your home. They produce more heat than the electricity they consume, often delivering three times the energy input. However, they still require a stable and reliable electrical connection.
Some homes, especially older properties, may not have an electrical system ready for this type of upgrade. The issue is not about higher energy usage. It is about whether your system can safely handle the electrical load when the thermal pump runs.
Before installation, your installer should:
- Check the current condition of your consumer unit
- Confirm if the wiring meets modern safety standards
- Recommend any necessary upgrades to protect your system
A professional assessment ensures your new heat pump operates safely, efficiently, and without risk of electrical faults.
Questions to Ask Before Signing a Contract
Homeowner and installer discussing heat pump plans for a home
Before committing to a heat pump installation, it’s important to ask the right questions. This helps you avoid surprises and ensures the system fits your home’s needs.
Here are the essential questions to ask your installer:
- How well insulated is my home?
Poor insulation increases heating demand. You may need a larger, more expensive system if your property lacks insulation.
- What type of heating system do I currently use?
Your existing system will impact the installation process and determine whether air source or ground source is a better fit.
- Is my electrical supply adequate?
Older homes may need upgrades to support the electrical demand of a heat pump.
- What kind of maintenance is required?
Regular servicing helps your system run efficiently and last longer.
- Have all necessary components been included in the quote?
Check for extras like descaling systems, buffer tanks, or upgraded radiators that might not be in the original estimate.
- Is planning permission required?
Rules have become more flexible, but listed buildings or conservation zones may still require special approval.
You should also confirm your installer’s certifications. Look for memberships with recognised industry bodies and proof of experience with both heat pump types.
Making the Final Decision: Practical Considerations
Choosing between an air source and a ground source heat pump comes down to more than just cost. Your property, long-term goals, and available space all play a role in making the right choice.
When an Air Source Heat Pump Makes More Sense
Air source heat pumps are ideal for homes with limited outdoor space. They need only a small external unit, which can be installed in compact gardens or on walls.
They are also more affordable upfront. Installation costs range from £8,000 to £18,000, making them accessible for many homeowners. The Boiler Upgrade Scheme grant can reduce this further by up to £7,500.
These systems are especially cost-effective when replacing oil, LPG, or electric heating. You may notice lower fuel bills right away. Plus, modern air-source setups offer built-in cooling features for the summer months.
When Ground Source Is Worth the Investment
Ground source systems deliver higher efficiency and long-term savings. They work well for homes with large outdoor spaces and good insulation.
Installation costs are higher, often starting at £14,500 and reaching up to £45,000. However, these systems offer greater efficiency and a longer lifespan. Many run for 20 to 30 years with proper maintenance.
The consistent ground temperature helps them perform well in all seasons. This is especially useful in colder areas or for families who plan to stay in their homes for many years.
Which Heat Pump is Best for You?
There is no one-size-fits-all answer when it comes to choosing a heat pump. The right system depends on your space, budget, and long-term plans.
Need help deciding between air-source vs ground-source heat pumps? Speak to our heating experts for clear, personalised advice.
Frequently Asked Questions
Q1. Which heat pump system is more cost-effective to operate?
Ground source systems are usually more efficient. They have lower running costs and reduced carbon emissions. However, they come with higher upfront installation costs. The best choice depends on your property and how long you plan to stay there.
Q2. Why might electricity bills increase after installing an air source heat pump?
Air source systems can use more electricity during very cold weather. This is because their efficiency drops as outdoor temperatures fall. A well-sized and properly installed system will reduce the impact.
Q3. What are the main drawbacks of ground source heat pumps?
The biggest concerns are the high initial cost, the need for outdoor space, and a more involved installation process. However, they offer better performance and longer lifespan if conditions are right.
Q4. How do air-source running costs compare to traditional systems?
They may cost more to run than a modern gas boiler. But they are far cheaper than oil, LPG, or electric heaters. Plus, you get cooling in the summer at no extra cost.
Q5. What factors should I consider when choosing between air and ground systems?
Key things to review include your outdoor space, insulation levels, current heating system, budget, and how long you plan to stay in the home. Always get a site survey from a certified installer before making a final decision.
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