Last Updated on June 30, 2025
Air source heat pumps and mini split systems are two highly efficient, low-carbon heating and cooling solutions. But when comparing air source heat pump vs mini split, which one makes the most sense for your property?
If you’re a UK homeowner, landlord, or small business exploring energy-efficient alternatives to traditional gas boilers, this guide breaks down the key differences helping you make a confident, informed decision.
Contents
Air Source Heat Pump vs Mini Split: A Quick Comparison
Here’s a side-by-side comparison of the most important factors UK property owners consider when choosing between these two systems:
| Feature | Air Source Heat Pump | Mini Split (Ductless Heat Pump) |
|---|---|---|
| Efficiency (SCOP) | 3.0 – 4.5 SCOP | 3.5 – 5.2 SCOP |
| Installation Costs | £8,000 – £18,000 (depending on system size & property type) | £2,000 – £8,000 (per indoor unit & setup) |
| Running Costs | ~£500 – £900/year (depending on usage & insulation) | ~£300 – £700/year |
| Maintenance Needs | Annual service required; external unit care needed | Minimal; occasional filter cleaning and checks |
| Lifespan | 15–20 years | 10–15 years |
| Carbon Emissions | Reduces emissions by up to 70% vs gas boilers | Lower carbon footprint than resistance heating |
| Installation Requirements | Outdoor space required; ideal for whole-house use | Indoor wall-mounted units; no ductwork required |
| Heating & Cooling | Primarily heating-focused; some models offer cooling | Strong dual functionality—heating and cooling |
| Grant Eligibility | Eligible for Boiler Upgrade Scheme (£7,500) | Not eligible for BUS; may qualify under other schemes |
How Do Air Source Heat Pumps Work?
Air source heat pumps extract latent heat from the outside air even in temperatures as low as -15°C. This heat is transferred via refrigerant to warm water for radiators, underfloor heating, and hot water cylinders. It’s an ideal solution for whole-home heating and can drastically lower your reliance on gas.
Below, I’ll discuss the pros and cons of air source heat pumps:
| Pros |
| Cons |
How Do Mini Splits Work?
Mini split systems (or ductless heat pumps) also pull heat from outside air, but instead of heating water, they deliver warm or cool air directly into individual rooms via wall-mounted indoor units.
These systems are more modular, making them perfect for retrofit applications or buildings without central ductwork.
| Pros |
| Cons |
Air Source Heat Pump vs Mini Split: Key Differences Explained
Choosing between an air source heat pump and a mini split depends on your property’s layout, budget, energy goals, and heating/cooling needs. Let’s take a closer look at the key factors.
Energy Efficiency
Mini splits generally offer slightly higher Seasonal Coefficient of Performance (SCOP) ratings, especially in well-insulated individual rooms.
However, air source heat pumps offer consistent whole-home heating efficiency, especially when paired with underfloor systems or low-flow radiators.
- Air Source Heat Pump Efficiency:
- Great for well-insulated homes
- Works best in steady, whole-home applications
- Great for well-insulated homes
For more insight into air source heat pump efficiency, including SCOP ratings and performance benchmarks, check our detailed post.
If you’re worried about performance in extreme weather, our article on how heat pumps work in cold weather addresses temperature-related concerns.
- Mini Split Efficiency:
- Ideal for zoned heating and cooling
- Higher SCOP in small spaces or extensions
- Ideal for zoned heating and cooling
Winner:
Mini splits edge out air source heat pumps in terms of raw efficiency, particularly in targeted, smaller zones. But the best choice still depends on your property’s heating needs.
Installation and Running Costs
Understanding both the upfront and ongoing costs can help you make the right decision based on your budget and energy usage. Here’s how air source heat pumps vs mini splits compare:
| Cost Category | Air Source Heat Pump | Mini Split (Ductless Heat Pump) | Estimated Monthly Savings | Estimated Annual Savings |
|---|---|---|---|---|
| Installation Costs | £8,000 – £18,000 (before grants)Eligible for £7,500 BUS grant | £2,000 – £8,000 per unit installed (typically not grant-eligible) | N/A | N/A |
| Running Costs (annual) | ~£500 – £900 depending on usage and insulation | ~£300 – £700 depending on room size and usage | £50 – £80 | £600 – £960 |
| Grants Available | Yes – Boiler Upgrade Scheme (BUS) | Rarely eligible under current UK schemes | N/A | N/A |
| Cost Effectiveness | Better value for larger, whole-home applications | More cost-effective for smaller or zoned spaces | Up to £80/month | Up to £960/year |
Note: Monthly and annual savings are estimated based on switching from traditional gas or direct electric heating systems. Actual savings will vary depending on property size, insulation quality, and usage habits.
You might also want to factor in the cost to replace a gas boiler with a heat pump if you’re planning a full system switch, or read up on detailed heat pump running costs to estimate long-term savings.
Winner:
Mini splits take the win for overall affordability especially in smaller properties or for targeted room-by-room heating.
That said, air source heat pumps become highly competitive when the Boiler Upgrade Scheme is factored in, making them a strong long-term investment for larger homes.
Maintenance & Servicing
Proper maintenance is crucial to keep both systems running efficiently and to extend their lifespan. Here’s how air source heat pumps and mini splits compare when it comes to upkeep and ongoing servicing:
Air Source Heat Pump Maintenance:
- Annual professional servicing is recommended to maintain efficiency and comply with manufacturer warranties.
- Outdoor unit checks are essential—debris, snow, or ice buildup can restrict airflow and reduce performance.
- Filters, coils, and heat exchangers need routine inspection and occasional cleaning to ensure smooth operation.
- May require refrigerant level checks, especially in older or larger systems.
- Typically included in annual service contracts offered by UK installers.
Mini Split Maintenance:
- Monthly filter cleaning is advised, especially during heavy use in summer or winter.
- Indoor units require occasional dusting and inspection to prevent airflow blockages.
- Servicing every 1–2 years is usually sufficient for refrigerant top-ups, electrical checks, and coil cleaning.
- No outdoor unit maintenance in single-zone systems (in some models), making upkeep easier.
- Ideal for hands-off homeowners with minimal HVAC knowledge.
Maintenance and Servicing Costs Comparison
| Maintenance Category | Air Source Heat Pump | Mini Split (Ductless Heat Pump) |
|---|---|---|
| Annual Servicing Cost | £150 – £250 per year | £70 – £150 every 1–2 years |
| DIY Maintenance Requirements | Regular outdoor unit checks, occasional filter cleaning | Monthly filter cleaning (quick and simple) |
| Parts Replacement (typical) | £100 – £300 (e.g. fan motors, sensors, valves) | £50 – £200 (e.g. filters, wall unit sensors) |
| Service Contracts Available | Yes – £10–£20/month plans from most UK installers | Limited availability; often handled ad hoc |
| Average 10-Year Maintenance Cost | £1,500 – £2,500 | £500 – £1,200 |
Winner:
Mini splits win on maintenance. Their minimal servicing needs and ease of access, combined with the absence of external units in certain models make them a lower-effort solution for busy homeowners or landlords looking to reduce long-term upkeep.
Lifespan
Air Source Heat Pumps:
Typically last 15–20 years with regular professional servicing. Their components are built for continuous, whole-home operation and are often covered by long-term warranties when installed by accredited providers.
Mini Splits:
Generally have a lifespan of 10–15 years, though indoor heads may require earlier replacement—especially in high-usage zones like living rooms or offices. Multi-split systems with multiple indoor units may see varied component lifespans.
Environmental factors—such as exposure to moisture, salt air, or heavy usage—can impact the longevity of both systems. Regular maintenance is key to achieving the upper end of their lifespan.
Winner:
Air source heat pumps are the winner here. They offer superior durability, with longer average lifespans and more robust components designed for year-round, whole-home heating.
Carbon Emissions
Air Source Heat Pumps can reduce carbon emissions by up to 70% when replacing a traditional gas boiler. They operate most efficiently in well-insulated homes and make a substantial contribution toward decarbonising heating under the UK’s net zero targets.
For a comparison of heat pumps with other low-carbon technologies, see our analysis of hydrogen boilers vs heat pumps and heat pumps vs biomass boilers.
Mini Splits also operate cleanly especially when powered by renewable electricity, but they’re typically used as supplementary heating or for individual zones. Their impact on total household emissions is therefore more limited, unless used extensively across the property.
Winner:
Air source heat pumps are the clear winner in the carbon emissions category. Their whole-home heating capability and compatibility with government-backed decarbonisation schemes make them a stronger choice for reducing your property’s overall carbon footprint.
Which Property Types Are Air Source Heat Pumps and Mini Splits Suited To?
Air Source Heat Pumps are well-suited for a wide range of properties in the UK, including detached houses, semi-detached homes, and newer builds with good insulation. They’re particularly effective in properties with sufficient space for an outdoor unit and low-temperature heating systems like underfloor heating or modern radiators.
If you’re unsure about compatibility, our guide on determining if your house is suitable for a heat pump provides a checklist of factors to consider.
- Do they work in old houses?
Yes. ASHPs do work in old houses but may require insulation upgrades to maximise efficiency. Loft and cavity wall insulation can significantly improve performance. - Planning permission:
Usually not required in England and Wales if installed under Permitted Development Rights, as long as certain conditions are met. Restrictions may apply in listed buildings or conservation areas.
Mini Splits (Ductless Heat Pumps) are ideal for flats, apartments, rental properties, and home extensions. Their modular, room-by-room design makes them popular for properties without central heating or for those that need zonal climate control.
- Do they work in old houses?
Yes, they can be effective in older homes, particularly where retrofitting central heating is too costly or disruptive. However, room-by-room heating may lead to uneven warmth unless multiple units are installed. - Planning permission:
Usually not needed for internal units. Outdoor condensers (if used) may fall under permitted development, but check with your local authority—especially in flats or shared buildings.
Do They Work with Existing Heating Systems?
Air Source Heat Pumps can work with existing heating systems, including boilers and radiators, but with some caveats. They operate most efficiently at lower flow temperatures, so pairing them with modern, larger surface area radiators or underfloor heating is ideal.
- If your existing radiators are small or sized for high-temp gas systems, they may need to be upgraded or replaced. Read our guide on how heat pumps work with existing radiators to get a better understanding.
- ASHPs can be used in hybrid systems where the gas boiler supports peak-time heating or hot water, common in less efficient or very large homes.
Mini Splits don’t connect to central water-based systems, so they won’t work with boilers or radiators. Instead, they deliver warm (or cool) air directly into the room via wall-mounted indoor units. This makes them more suitable for standalone heating/cooling rather than as a complete central heating replacement.
Space Requirements
Air Source Heat Pumps require:
- An outdoor unit roughly the size of a small fridge freezer, which needs good airflow and clearance from walls and obstructions.
- Indoor components like a hot water cylinder (in air-to-water systems) and occasionally a buffer tank or control unit.
- Piping infrastructure to connect the system to underfloor heating or radiators, which may require space in utility rooms or airing cupboards.
You’ll need outdoor space, typically a back garden, side return, or even a sturdy flat roof area. Terraced homes may require creativity in placement but are still viable with the right planning.
Read our in-depth guide on how much space you will need for an air source heat pump.
Mini Splits are more space-flexible:
- Indoor units are mounted high on interior walls and don’t require any floor space.
- Outdoor units (in multi-split setups) are compact and can be wall-mounted or placed at ground level.
- Single-room mini splits often require no indoor reconfiguration, making them perfect for tight or awkward spaces.
- If you’re looking for alternatives that also provide zonal control or heating without plumbing, see our comparison of heat pumps and electric radiators.
In summary, air source heat pumps need more planning and physical space, while mini splits offer easier, low-impact installation, ideal for space-constrained properties or retrofits.
Want to Reduce Your Heating Bills? Request a Free Air Source Heat Pump Quote Today
Ready to ditch high gas bills and future-proof your property? Whether you’re a UK homeowner or landlord, installing an air source heat pump could slash your carbon footprint and unlock long-term savings.
Eco Happy specialises in fully-funded air source heat pump installations under the Boiler Upgrade Scheme (BUS). We’ll help you determine your property’s eligibility, advise on the best system for your needs, and handle the entire process, start to finish.
Get a FREE air source heat pump quote today and discover how much you could save.
James Elston
Boiler Expert
James Elston is the top boiler replacement and heating expert at Eco Happy. He has over 20 years of experience in the industry, focusing on Gas Safe boiler installations and offering home-heating and energy-saving solutions to homeowners across the UK. From sourcing the most energy-efficient combi boiler to providing specialist heating advice, James ensures that Eco Happy maintains the highest standards and best customer service.