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Mini Split Heat Pumps in the UK: Costs, Types & Benefits (2025)
- A mini split heat pump is a heating and cooling system that controls the temperature in specific rooms without using ducts.
- The cost of a mini split heat pump typically ranges from £1,500 to £5,000+, depending on the unit's size, efficiency, and installation complexity.
- Its biggest benefits are suitability for older homes and ease of installation.
A typical problem for many homes: cold in the winter, boiling in the summer. Unfortunately, traditional heating and cooling systems don’t always cut it, especially in older UK homes where central ductwork isn’t an option.
That’s why so many people turn to mini split heat pumps. No major renovations, no ripping up walls—just targeted heating and cooling where you need it. Simple and efficient.
But here’s the real question: are they worth it? And what do they actually cost? In this guide, we’ll break down prices, types, pros and cons. So you can easily decide if a mini split system is the right move for your home.
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What is a split heat pump?
A split heat pump is a heating and cooling system with two main parts: an outdoor unit and an indoor unit. These are connected by insulated pipes and electrical wiring.
The outdoor unit has a compressor and a heat exchanger coil (condenser). The indoor unit has another coil and a fan that blows warm or cool air into the room.
In heating mode, the system absorbs heat from the outside air and moves it indoors. In cooling mode, it works in reverse, pulling heat from inside your home and releasing it outside.
To understand it even better, imagine a reversible fridge. A refrigerator moves heat out to keep food cold. A split heat pump does the same but can switch directions to heat or cool your home.
When used in homes, these systems are often called mini-splits because they are compact and flexible.
How does a mini split heat pump work?
All heat pumps—whether it's a mini split, ducted system, or monobloc heat pump—operate on the same fundamental principle: moving heat rather than generating it.
The main difference with mini split heat pumps is that they don’t need ducts. Instead, they heat or cool specific rooms directly using indoor units.
Here is how the mini split heat pumps work for different modes:
Heating mode
Even in cold weather, the outdoor unit absorbs heat from the air. The refrigerant inside picks up this heat and turns it into a gas. The system then compresses this gas, making it much hotter. The hot refrigerant travels to the indoor unit, where it releases heat into the room.
After giving off its heat, the refrigerant cools back into a liquid and flows outside to start the process again.
Cooling mode
In cooling mode, the process reverses. The indoor unit's coil gets cold as the refrigerant inside evaporates, absorbing heat from the indoor air. A fan blows over the cold coil, cooling and dehumidifying the room.
The refrigerant, now carrying the heat, flows to the outdoor unit, where it releases the heat outside and turns back into a liquid. The cooled refrigerant then returns inside to continue the cycle.
Types of mini split heat pumps
Mini split heat pumps have two parts: an outdoor unit and an indoor unit. However, they come in different configurations depending on how many indoor units they have and how they distribute air.
Here are the most popular types:
- Single split systems: One outdoor unit is connected to one indoor unit. Ideal for heating or cooling a single room or an open-plan area. Common in small homes or as a supplementary system for one space.
- Multi split heat pump: One outdoor unit connects to multiple indoor units (usually 2–5). Each indoor unit can be placed in a different room and controlled independently. Best for heating or cooling multiple rooms, though installation is more complex.
- Wall-mounted units: Installed high on a wall. They are relatively compact (often only about 7–8 inches deep) and can efficiently distribute air. It is the most common and easiest to install option.
- Ceiling cassettes: Mounted into the ceiling, with a vented grille visible. Blows air in multiple directions. Ideal for larger rooms but requires ceiling space for installation.
- Floor-mounted or console units: Installed at floor level, similar to a radiator. Best for rooms with limited wall space. They are useful where mounting high is not possible (for example, if the wall is all glass, or in an attic room with low knee-walls).
- Ducted mini-split units: The indoor unit is hidden in a loft, ceiling void, or cupboard and connects to small ducts. Allows for multiple rooms to be heated or cooled while keeping the unit out of sight.
- Other configurations: Some brands make ceiling-suspended units that hang from the ceiling or vertical air handlers that connect to a mini split outdoor unit, but these are more common in commercial buildings.
You can also set up mini split hybrid heat pumps. These systems combine the efficiency of a mini split heat pump with the reliability of a traditional heating system, usually a gas or oil furnace. They will automatically switch between electric heat pump operation and the backup heating source based on outdoor temperatures and energy efficiency.
How much does a mini split heat pump cost?
Air source heat pump costs in the UK vary widely depending on the system size, the number of indoor units, the brand, and the difficulty of installation.
Below, we’ve compared typical costs by system type, including air source heat pump installation and an estimate of maintenance:
| System type | Typical installed cost | Annual maintenance cost |
|---|---|---|
| Single-zone mini split (one indoor unit & one outdoor unit) | £1,500 – £3,000 | £80 – £120 |
| Multi-zone mini split (2–3 indoor units, one outdoor) | £3,000 – £5,000 | £160 – £320 |
| Large multi-split (4+ indoor units on one outdoor) | £5,000 – £9,500+ | £320+ |
These prices are rough estimates for typical home installations. A small 2.5kW single-room unit is more affordable, while a larger or premium unit comes at a higher cost. Multi-split systems increase in price as more indoor units are added, since setups for multiple rooms require a bigger investment.
Keep in mind that ceiling cassette and ducted indoor units tend to be more expensive, often £2,500–£4,000+ per indoor unit.
These prices include both the equipment and standard installation by an F-Gas certified engineer. The installation covers the mounting of units, running refrigerant lines, electrical connections, and system commissioning. Labour costs alone can be £960–£1,380 per indoor unit.
Mini split heat pumps (air to air heat pumps) are not eligible for the UK government’s main incentive programs, such as the Boiler Upgrade Scheme. These grants only support air to water heat pumps and ground source heat pumps, meaning there is no financial assistance for mini split installations.
The cost of a mini split heat pump in the UK will be affected by potential extras and installation costs, which vary by installer.
That’s why it’s best to compare several heat pump installers in your area.
Instead of spending days on research and comparisons on your own, why not fill out our 30-second form and let us do the rest? We’ll find you up to 4 free air source heat pump quotes from trusted installers in your area.
Click below to get started!
- Quotes from local engineers
- Payment by finance available
- Save £7,500 with BUS grant
Mini split heat pump installation
Installing a split air source heat pump requires a qualified HVAC (heating, ventilation and air conditioning) engineer. In the UK, they must have F-Gas certification to handle refrigerants.
The installation process is usually faster and less disruptive than installing a full central heating system since no large ductwork or water pipes are required.
Let’s go over the mini split heat pump installation process step by step:
- Planning & placement: The installer chooses the best locations for the indoor and outdoor units. Indoor units are usually placed high on an external wall, while the outdoor unit needs a stable base with good airflow. A 7–8cm hole is drilled for refrigerant lines, drain, and wiring.
- Mounting the indoor unit: A mounting bracket is fixed to the wall, and the indoor unit is attached. The hole for the pipes is slightly sloped downward for drainage. In multi-split systems, this is done for each unit.
- Installing the outdoor unit: The outdoor unit is placed on a concrete pad or wall bracket and bolted down to prevent vibration. It’s positioned to keep the pipe short and minimise noise disturbance.
- Connecting refrigerant lines & wiring: Two insulated copper pipes run between the indoor and outdoor units to move refrigerant. An electrical cable powers the indoor unit, and a drain hose removes moisture. Pipes and cables are usually covered with plastic trunking for a cleaner look.
- Vacuum & refrigerant charging: The system is vacuumed to remove air and moisture before releasing refrigerant. If the pipe length exceeds 5m, extra refrigerant may be added. The installer checks for leaks using gauges and detectors.
- Electrical hookup: The outdoor unit is wired to the consumer unit (fuse box) with a 16A or 20A breaker and an isolation switch. Indoor units are connected to the outdoor unit with a control cable for communication.
- Testing & commissioning: The system is switched on and tested in heating and cooling modes. The installer checks airflow, temperature, and thermostat response.
Pros and cons of a split system heat pump
Like any heating/cooling technology, heat pump split systems come with a set of advantages and disadvantages. Here are the key pros and cons of using a split system heat pump in a UK home:
- High energy efficiency: Mini split heat pumps can deliver 3 to 4kWh of heat for every 1kWh of electricity used, while electric heaters work at a 1:1 ratio. In cooling mode, they are also more efficient than portable or window AC units. Avoiding ductwork further reduces energy losses, which can be over 30% in central ducted systems.
- Provides both heating and cooling: The same system heats in winter and cools in summer. Many UK homeowners install mini splits to add air conditioning while also supplementing or replacing heating.
- Zoned climate control: Multi-split systems allow independent temperature control in each room, which saves energy and customises comfort. Even single-split systems offer zoning by focusing heating or cooling where it’s needed.
- No ductwork or water pipes needed: Mini splits don’t require air ducts, radiators, or underfloor heating pipes. This makes installation easier, especially in older homes without existing ductwork.
- Quick and simple installation: A single-unit system can be installed in one day, with only a small hole through the wall required.
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No central hot water heating: Mini splits don’t provide hot water for taps or showers. They only heat rooms. A separate boiler, electric immersion heater, or water heater is needed.
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Limited whole-house heating for larger homes: Mini splits are great for smaller homes or specific rooms, but heating an entire large home with them can be expensive.
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Higher upfront cost for multiple units: While single-room mini splits are affordable, installing units throughout a home can be costly. A system with four indoor units and one outdoor unit can cost £5,000–£6,000+ with installation. This price is comparable to a central air to water heat pump system, which can qualify for air source heat pump grants.
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No government grants available: Unlike air to water and ground source heat pumps, mini splits don’t qualify for UK government subsidies. Homeowners must cover 100% of the cost.
Is a mini split heat pump the right choice for my home?
If you require both heating and cooling or want better temperature control in a specific area, a mini split heat pump might be exactly what you need.
These systems work particularly well in homes where traditional heating setups don’t hold up, like older properties that call for air conditioning or houses without a gas connection.
More and more homeowners replace boilers with heat pumps, and for good reason. Traditional gas and oil boilers are less efficient, often wasting energy and driving up heating bills. Heat pumps, on the other hand, operate at 300–400% efficiency. This means they produce far more heat for every unit of electricity used.
Keep in mind that your local climate plays a big role in choosing the right system:
- England has a temperate maritime climate, meaning winters are mild and summers can heat up. The recommended type is inverter-driven heat pumps with a SCOP of 4.0+ for efficiency.
- Wales has high rainfall, strong coastal winds, and moderate winters. This means you need a system that can hold up against moisture. The best air source heat pumps for Wales are anti-corrosion models with a strong defrost mode to prevent efficiency loss.
- Scotland has colder winters than the rest of the UK. Standard heat pumps give out at low temperatures, so the best air source heat pumps for Scotland are cold-climate models.
- Northern Ireland has a mild but wet climate, with coastal areas facing high humidity and inland areas experiencing colder winters. The best air source heat pumps for Northern Ireland are hybrid heat pumps or standard high-efficiency models with corrosion resistance.
If you think a mini split might work out for you, the next step is to get quotes from qualified installers. They can help you choose the correct unit size, number of indoor units, and the best air source heat pump brands for your home.
There are 2 ways to compare heat pump installers in your area:
1. Spend hours of your spare time searching for them on your own.
2. Fill out our 30-second form and let us do the hard work for you.
We’ll connect you with up to 4 trusted installers in your area. Click below to get started!
- Quotes from local engineers
- Payment by finance available
- Save £7,500 with BUS grant
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