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Heat Pump Cost Calculator — Installation, Grants and Savings
Estimate the full cost of installing a heat pump in the UK. Includes BUS grant deduction, running cost comparison vs your current heating, payback period and CO2 savings.
Ofgem price cap, Jul–Sep 2026 (changes each quarter — override with your tariff rate)
Auto-updates when you change heating type (defaults: gas 7.33, oil 7.5, LPG 9.1, electric 26.11 p/kWh — mid-2026). Oil 7.5 p/kWh ≈ 78p/litre kerosene (10.35 kWh/L); LPG default is a bulk-tank central-heating rate (bottled/small-bulk LPG can be ~13 p/kWh) — override with your own.
Auto-calculated from property size — override if you know your usage
Auto-updates for ASHP (3.5) or GSHP (4.0) — higher is more efficient
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How We Calculate This
Installation Costs
Total installation cost is estimated based on your property size and heat pump type. It includes the heat pump unit, labour and installation, electrical work, and optional extras like radiator upgrades and hot water cylinder. Larger properties need higher-capacity units with more complex installation, so costs scale accordingly.
- ASHP typically costs £6,900–£14,000 installed (smaller flats at the lower end)
- GSHP typically costs £14,000–£29,000 installed (includes ground works)
This calculator compares both types side by side. For a ground source system specifically, the ground source heat pump cost calculator sizes GSHP capacity and running costs from your property, garden area and ground type.
BUS Grant
The Boiler Upgrade Scheme (BUS) provides a £7,500 grant towards heat pump installation in existing homes in England and Wales. The grant is deducted from the total cost at the point of installation — you do not pay the full amount upfront.
- Must use an MCS-certified installer
- Property must have a valid EPC
- No outstanding loft or cavity wall insulation recommendations on EPC
- Applies to both ASHP and GSHP installations
Running Cost Comparison
The coefficient of performance (COP) measures how efficiently the heat pump converts electricity into heat. A COP of 3.5 means 1 kWh of electricity produces 3.5 kWh of heat. Annual running cost = heat demand ÷ COP × electricity price. Your current system cost = heat demand ÷ boiler efficiency × fuel price.
- ASHP seasonal COP: typically 3.0–4.0 (default 3.5)
- GSHP seasonal COP: typically 3.5–5.0 (default 4.0)
- Payback period = net cost after grant ÷ annual saving
Why Radiators Matter
Heat pumps work most efficiently at lower flow temperatures (around 45°C vs 65°C for a gas boiler). At lower temperatures, radiators need a larger surface area to deliver the same heat output. A professional heat loss survey will identify which rooms need upgraded radiators. In well-insulated homes, existing radiators may be adequate.
Carbon Savings
CO2 savings are calculated using the SAP 10.2 carbon factors (Table 12) that underpin Building Regulations Part L and EPCs. SAP 10.2 puts grid electricity at 0.136 kgCO2/kWh — already lower than mains gas (0.210), heating oil (0.298), and LPG (0.241). Because the heat pump multiplies each kWh of electricity by the COP, the effective emissions per kWh of heat delivered are far lower again (e.g. at COP 3.5, only 0.039 kgCO2 per kWh of heat). As the grid continues to decarbonise, heat pump carbon savings will increase further.
Frequently Asked Questions
A typical air source heat pump (ASHP) costs around £6,900–£14,000 installed in the UK (the lower figure applies to a small 1–2 bed flat; a 3-bed semi is roughly £10,000), while ground source heat pumps (GSHP) range from £14,000–£35,000 depending on property size and ground conditions — small systems start around £14,000 and large borehole installations reach the top of the range. These figures include the unit, labour, electrical work and commissioning. The £7,500 BUS grant can significantly reduce the net cost.
The Boiler Upgrade Scheme (BUS) provides a £7,500 grant towards heat pump installation in existing homes in England and Wales. You must use an MCS-certified installer, and the property must have a valid EPC with no outstanding loft or cavity wall insulation recommendations. The grant is applied at the point of installation — you do not need to pay the full cost upfront.
It depends on the coefficient of performance (COP) and, crucially, on the ratio between electricity and gas prices (the "spark gap"), which shifts every Ofgem cap period. At the Ofgem price cap for 1 July–30 September 2026 (electricity 26.11p/kWh, gas 7.33p/kWh, Direct Debit), a heat pump produces heat more cheaply than a 90% efficient gas boiler once its seasonal COP reaches about 3.2 (breakeven: 26.11 ÷ (7.33/0.90) = 3.2). Most modern air source heat pumps achieve a seasonal COP of 3.0–4.0, so a well-designed system at COP 3.5+ is usually cheaper to run than gas at these rates. Because the spark gap moves each quarter, re-check with your own tariff — a time-of-use or heat-pump tariff tips the balance much further in the heat pump’s favour.
Often yes. Heat pumps operate most efficiently at lower flow temperatures (around 45°C versus 65°C for a gas boiler). At lower temperatures you need larger radiator surface area to deliver the same heat output. A professional heat loss survey will identify which rooms, if any, need larger radiators. In well-insulated homes the existing radiators may be adequate.
Air source heat pumps are far more common (over 90% of UK installations) because they are cheaper to install and require no ground works. Ground source heat pumps achieve higher COPs (typically 4.0 vs 3.5) and are quieter in operation, but cost roughly double to install due to borehole drilling or trench excavation. GSHP is best suited to larger properties with available land, while ASHP works well for most homes.
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Last updated: July 2026
Verified against UK standards · estimates only, confirm with your supplier.