Heat Pump Grant Calculator (UK BUS 2026)

UK Heat Pump Guide 2026

What's the key thing to understand about The Boiler Upgrade Scheme (BUS) 2026?

The BUS provides upfront grants for switching from fossil fuel heating to a heat pump or biomass boiler. Current grant levels (as of 2026/27): air source heat pump (ASHP) £7,500. Ground source heat pump (GSHP) £7,500. Biomass boiler £5,000 (rural off-gas-grid only). The grant is paid to the installer, who deducts it from your bill — you pay only the net cost. Eligibility: must be a MCS-certified installer; must be replacing fossil fuel heating; valid EPC required, with no outstanding loft or cavity wall insulation recommendations unless there's a good reason they can't be installed.

What's the key thing to understand about True Cost of Installation?

Average UK heat pump installation costs 2026: ASHP £10,000-15,000 typical (£12,500 average) — net of grant: £2,500-7,500. GSHP £18,000-30,000 typical — net of grant: £10,500-22,500. Hybrid systems £8,000-14,000 typical. Additional costs that may apply: radiator upgrades (heat pumps work at lower flow temperatures, so existing radiators may be undersized) £100-300 per radiator replaced; hot water cylinder if you currently have a combi boiler £500-1,500; electrical supply upgrade £200-2,000 if the existing supply isn't sufficient for the heat pump's electrical demand.

What's the key thing to understand about Running Cost Reality?

The energy crisis years have changed heat pump economics significantly. As of 2026: heat pumps achieve real-world COP (coefficient of performance) of 2.5-3.5 in UK conditions. So 1 kWh of electricity produces 2.5-3.5 kWh of heat. Gas boilers have efficiency around 0.85-0.92 — 1 kWh of gas produces 0.85-0.92 kWh of heat. Current unit rates: electric ~28.6p/kWh, gas ~6.4p/kWh. Per useful kWh of heat: heat pump costs ~9-11p/kWh; gas boiler costs ~7-7.5p/kWh. THIS MEANS GAS IS STILL CHEAPER per kWh of delivered heat under standard tariffs — the case for a heat pump rests on efficiency (a heat pump moves 3-4 units of heat per unit of electricity, a gas boiler converts roughly 0.85-0.92 units) and on the £7,500 grant reducing the upfront cost gap, not on the per-kWh price alone.

When Heat Pumps Actually Pay Back Fast?

Best-case scenarios: (1) Replacing oil heating in rural homes — oil at 7.5p/kWh × 0.85 efficiency = 8.8p/useful kWh; heat pump at 9-11p/useful kWh competitive PLUS no fuel deliveries. (2) Well-insulated newer homes where heat pump runs at high COP (3.5+) — drops cost to 8p/useful kWh, cheaper than gas. (3) Combined with solar PV that powers daytime heat pump operation — effectively free heat for sunny periods. (4) Octopus Cosy tariff — 4-6 hours/day of 13p/kWh electric — combined with thermal storage (a hot water cylinder or thermal battery) to shift most heating into the cheap electricity window — these tariff-optimised setups pay back significantly faster than a heat pump on a standard variable tariff.