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Heat Pump Calculator — UK 2026

Running costs vs your boiler, £7,500 BUS grant, payback period — AI-explained.

Heat pump type

ASHP: installed outside, SCOP ~2.8. Most common, lower upfront cost.

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Get quotes from MCS-certified heat pump installers

Your installer handles the £7,500 BUS grant application on your behalf. Up to 3 no-obligation quotes, typically within 2 business days.

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Heat pumps in the UK — costs, grants, and performance (2026)

Heat pumps extract heat from the outdoor air (air source) or ground (ground source) and transfer it into your home, achieving efficiencies of 2.5–3.5× the electricity they consume. In 2026, the UK government is incentivising the switch from fossil fuel boilers via the Boiler Upgrade Scheme — a £7,500 grant paid directly to your MCS-certified installer.

The running cost question

The most common question is whether heat pumps are cheaper to run than gas boilers. At current Ofgem price cap rates (electricity 24.5p/kWh vs gas 6.24p/kWh), a heat pump with SCOP 2.8 costs ~8.75p per kWh of heat delivered. A modern gas boiler at 89% efficiency costs ~7p/kWh. The current gas-electricity price ratio makes heat pumps marginally more expensive to run for gas users — but significantly cheaper for oil (7.5p/kWh boiler efficiency ~85%, effective ~8.8p/kWh) and LPG users.

The Boiler Upgrade Scheme — how it works

The BUS grant is paid directly to your MCS-certified installer, who deducts it from your invoice. You cannot apply directly — your installer applies on your behalf. Eligibility conditions include: property is in England or Wales, the heating system being replaced is oil, gas, or electric (not a biomass system in most cases), and the property must have a valid EPC. The grant is £7,500 for both air source and ground source heat pumps.

This content is reviewed by James Thornton (MCS).

Frequently Asked Questions

What is the Boiler Upgrade Scheme (BUS) grant?

The Boiler Upgrade Scheme (BUS) is a UK government grant providing £7,500 towards the cost of installing an air source or ground source heat pump in England and Wales. The grant is paid directly to your MCS-certified installer, who deducts it from your bill. You do not apply yourself — your installer handles the application. The scheme is available to homeowners and small business landlords replacing fossil fuel heating systems.

How does SCOP affect running costs?

SCOP (Seasonal Coefficient of Performance) is the annual average efficiency of a heat pump. An ASHP with SCOP 2.8 produces 2.8 units of heat for every 1 unit of electricity. This means if you pay 24.5p/kWh for electricity, the effective heat cost is ~8.75p/kWh — comparable to gas (6.24p/kWh) but more expensive per unit. However, a ground source heat pump with SCOP 3.5 can get the effective cost down to ~7p/kWh, closer to gas parity.

Are heat pumps cheaper to run than gas boilers?

At current UK energy prices (electricity ~24.5p/kWh vs gas ~6.24p/kWh), a heat pump typically costs more to run than a modern gas boiler per kWh of heat produced — even accounting for the higher SCOP. Running costs are closest for ground source heat pumps in well-insulated homes. However, oil and LPG users often find heat pumps significantly cheaper to run. The economics improve as the gas-electricity price ratio narrows and the grid decarbonises.

What EPC rating do I need for a heat pump?

While there is no legal EPC requirement to install a heat pump, MCS guidelines and industry best practice recommend a minimum EPC rating of C. Heat pumps deliver heat at lower temperatures than boilers, making insulation more important for efficiency. Poorly insulated homes (D or below) may need additional investment in loft and wall insulation before a heat pump performs well. Your installer will carry out a heat loss survey.

Is the BUS grant available in Scotland?

The Boiler Upgrade Scheme is available in England and Wales only. Scotland has its own scheme — Home Energy Scotland grants and loans are available for heat pumps through the Scottish Government and Energy Saving Trust. Scotland has historically offered more generous support. Check the Home Energy Scotland website for current grant amounts.

What size heat pump do I need?

Heat pump sizing is based on a heat loss calculation of your property — typically carried out by an MCS-certified installer. As a rough guide, most UK homes need a 5–12 kW heat pump. Oversizing is counterproductive: a heat pump that is too large will cycle on and off, reducing efficiency. This calculator uses a simplified heat demand model based on property size; always get a proper heat loss survey from an installer.

Do heat pumps work in cold weather?

Modern air source heat pumps operate efficiently down to -15°C or lower. In very cold UK winters (rare), performance does reduce, but the SCOP figure already accounts for the full UK seasonal range. Heat pumps need to run longer at lower temperatures to maintain the same heat output, which is why good insulation is important. Ground source heat pumps are largely unaffected by outdoor temperature.