Air Source Heat Pump Installation

Replace your gas boiler with an air source heat pump and cut your home's carbon emissions by around 70%. The £7,500 Boiler Upgrade Scheme grant brings the after-grant cost of most installations to between £500 and £6,500 - comparable to fitting a new gas boiler, without the gas connection.

Key Numbers (2026)

Installation cost (before grant)	£8,000-£15,000
BUS grant (England & Wales)	£7,500
Typical after-grant cost	£500-£6,500
Seasonal efficiency (SCOP)	3.5-4.5
Annual running cost (average home)	£840-£1,700
Carbon emission reduction vs gas	~70%
Expected system lifespan	20+ years
0% VAT on supply and installation	Until March 2027

How Air Source Heat Pumps Work

An air source heat pump extracts heat from outdoor air and transfers it into your central heating system and hot water cylinder. Even in cold weather, there's usable heat in the air - heat pumps operate efficiently down to around -20°C.

The system runs on electricity rather than burning fossil fuel. For every unit of electricity it consumes, a well-installed heat pump produces 3 to 4.5 units of heat - a seasonal efficiency of 300-450%. A gas boiler, by contrast, converts roughly 90% of the gas it burns into heat. At current Ofgem rates (electricity 24.5p/kWh, gas 6.4p/kWh), running costs sit at near parity with gas, and the gap narrows further if you're on a heat pump-specific tariff like Cosy Octopus.

Heat pumps work best at lower flow temperatures - typically 35-45°C rather than the 60-70°C of a gas boiler. This means your existing radiators may need upgrading to larger ones, or the system works best with underfloor heating. Your installer will calculate your home's heat loss and specify exactly what changes are needed before any work starts.

Heat Pump Types

Air-to-water heat pumps are the most common choice for UK homes. They connect to your existing wet central heating system - radiators or underfloor heating - and provide central heating and hot water via a hot water cylinder. Compatible with most homes that currently have a combi boiler or conventional boiler setup. Trusted brands: Mitsubishi Electric, Daikin, Vaillant, Samsung. SCOP: 3.5-4.5

Air-to-air heat pumps transfer heat from outdoor air directly into the air inside your home through internal units. They provide heating and cooling but don't heat water, so a separate hot water solution is needed. Better suited to smaller properties or supplementary heating in specific rooms. Trusted brands: Mitsubishi Electric, Daikin, Panasonic, Fujitsu. SCOP: 4.0-5.0

Hybrid heat pump systems pair a heat pump with your existing gas boiler. The system automatically switches between the two depending on which is more efficient at the current outdoor temperature. Trusted brands: Vaillant, Bosch, Viessmann, Worcester Bosch. Overall SCOP: 3.0-4.0

Ground source heat pumps extract heat from the ground via buried pipework or boreholes. They're more efficient than air source heat pumps but installation costs run £20,000-£30,000 before grants, and your garden or land needs to accommodate the ground loop.

The Boiler Upgrade Scheme Grant

The Boiler Upgrade Scheme (BUS) provides a £7,500 grant for air source and ground source heat pump installations in England and Wales. The grant comes off your installation cost directly - you don't pay it upfront and claim it back.

The budget for 2025/26 is £295 million. As of 2026, the requirement for a valid EPC at point of application has been relaxed, making it easier for older properties and those mid-renovation to access the grant without delays.

Additional funding routes:

• Warm Homes Local Grant - for eligible low-income households
• 0% VAT on supply and installation until March 2027
• Enhanced Capital Allowances for businesses investing in energy-efficient equipment

We handle the entire BUS application process. You confirm eligibility; we submit the paperwork.

Is Your Home Suitable?

Heat pumps perform best in well-insulated homes. Loft insulation, cavity wall insulation, and draught-proofing all improve efficiency and reduce running costs. Before installation, an engineer conducts a heat loss calculation to determine the exact heating demand of your property.

Practical requirements:

• Outdoor space for the external unit, with adequate airflow around it
• Indoor space for a hot water cylinder (roughly the size of a large fridge-freezer)
• Electrical supply capable of handling the new load
• Sufficient insulation - your installer will advise on any improvements needed

The Installation Process

Day 1-2: Survey and preparation. An engineer surveys your property, conducts the heat loss calculation, assesses your existing heating system, and confirms the BUS grant application.

Day 2-4: Installation. The external unit is positioned outside. Indoor components connect to your existing pipework. Radiator upgrades or a new hot water cylinder are fitted where needed. Most installations take around five days total.

Day 4-5: Commissioning and handover. The system is tested for leaks, flow temperatures are set, and your engineer walks you through the controls and heating preferences.

Running Costs and Savings

At 2026 Ofgem price cap rates - electricity at 24.5p/kWh and gas at 6.4p/kWh - heat pump running costs sit close to gas boiler costs for most homes. Octopus Energy data from March 2025 to March 2026 shows heat pump customers saving an average of £219 per year compared to gas boiler users on a standard tariff.

Over a 20-year lifespan, the Energy Saving Trust estimates heat pumps save approximately £3,900 compared with gas. Combining a heat pump with solar panels significantly improves the financial case.

FAQ

How much does heat pump installation cost after the grant? Most homeowners pay £500 to £6,500 after the £7,500 BUS grant, based on typical installation costs of £8,000 to £15,000 before the grant.

Does my home need to be well insulated? Good insulation improves efficiency and lowers running costs. Your installer will assess your current insulation during the survey.

Will my existing radiators work? Some homes need larger radiators to work at the lower flow temperatures heat pumps use. Your engineer calculates this as part of the heat loss assessment.

Do I need planning permission? Most installations are permitted development. Conservation areas and listed buildings are exceptions.

Can I combine a heat pump with solar panels? Yes - and it's one of the most effective combinations available. Your solar panels generate electricity during the day; your heat pump uses it for heating and hot water.