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.

Why Grant Schemes Change Frequently and Vary by Nation

Government support for heat pump installation — whether structured as a direct grant, a voucher, or a reduction applied at the point of installation — has changed shape and funding level multiple times as energy and climate policy has evolved, and the scheme available can differ between England, Scotland, and Wales, with different administering bodies and eligibility rules in each. Because of this volatility, any specific grant amount should be checked against the current scheme details at the time of actually applying, rather than relying on a figure that may reflect a previous iteration of the scheme that has since been revised, replaced, or had its funding level changed.

What Usually Determines Eligibility Beyond the Headline Grant Figure

Beyond the grant amount itself, eligibility for heat pump support schemes commonly depends on factors like the type of property, whether it's owner-occupied or privately rented, the installer being certified under a recognized quality scheme, and sometimes a requirement that the property meets a minimum standard of insulation first — since a heat pump's efficiency and running cost depend heavily on how well the building retains heat. Combining a grant with the underlying running-cost comparison against the heating system being replaced (usually gas) gives a fuller financial picture than the grant amount alone, since a heat pump's higher upfront cost even after a grant may still take a number of years to be offset by lower running costs, depending on relative electricity and gas prices and the home's heat demand.

Why Correct Sizing Matters More Than the Grant Amount

<p>An undersized heat pump struggles to reach temperature on the coldest days and relies on inefficient backup heating to make up the gap, while an oversized one cycles on and off more than it should, wearing components faster and running less efficiently than a correctly matched system. Proper sizing depends on a heat loss survey of the specific property — its insulation, floor area, window performance and existing radiators or underfloor heating — not a rule of thumb based on square footage alone. This matters for the economics as much as comfort: a correctly sized heat pump paired with suitably sized radiators (often larger than the radiators a gas boiler needed, since heat pumps run at lower flow temperatures) delivers the efficiency that makes the running-cost case work. Skipping or rushing the heat loss survey is one of the most common reasons a heat pump installation underperforms the savings a grant calculator or installer quote implied, regardless of how large the upfront grant was.</p>

Worked Example: Grant, Net Cost and Payback for a Typical Home

Say a semi-detached house needs an air source heat pump (ASHP) quoted at £13,000 installed, replacing an ageing gas boiler. Under a scheme like the Boiler Upgrade Scheme, a grant currently in the region of £7,500 is available for an ASHP (check the current figure before budgeting, as these grants are reviewed and can change). That brings the net upfront cost to £5,500. If the heat pump cuts annual heating and hot water costs from roughly £1,400 (gas) to £1,150 (efficient ASHP running on typical electricity tariffs), the saving is about £250 a year — a simple payback on the net cost of roughly 22 years. That number changes a lot with three inputs: the size of the grant actually received, how well the system is sized and commissioned, and the gap between your electricity and gas unit rates. A well-sized heat pump in a well-insulated home, replacing an old G-rated boiler, can show payback in well under 10 years; a poorly sized one replacing a modern condensing boiler may never clearly pay back on running costs alone, and the case then rests more on carbon reduction and removing a gas connection.

Grant Amounts and Eligibility Vary Significantly by UK Nation

Heat pump grant schemes are not uniform across the UK, and mixing up figures from one nation with another is one of the most common planning mistakes.

Beyond the headline amount, eligibility commonly depends on things like property type, whether you own or rent, whether there's an existing fossil-fuel heating system being replaced, and sometimes an EPC or insulation threshold. Funding pots can also be reviewed annually or paused when a budget allocation is exhausted, so always confirm current availability with the official scheme portal rather than relying on a figure you saw even a year ago.