Heat Pump Cost Calculator — Installation, Grants and Savings

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.