Heat Pump vs Gas Boiler: Real Running Cost Comparison 2026

To compare running costs fairly, you need three figures: the efficiency of each system, the fuel price, and your home’s annual heat demand.

Gas boiler: A modern condensing boiler operates at roughly 90% efficiency in real-world conditions (not the 94% on the data sheet). At a gas price of 7p/kWh, the cost per kWh of useful heat is about 7.8p.

Air source heat pump: A well-designed system achieves a seasonal COP (SCOP) of 3.5–4.0. At an electricity price of 24p/kWh, the cost per kWh of useful heat is 6–6.9p.

For a typical three-bedroom house with an annual heat demand of 12,000 kWh, that translates to:

• Gas boiler: £936/year • Heat pump: £720–£828/year

The heat pump is already cheaper to run — and this gap widens significantly with solar panels.

If you pair your heat pump with a 4 kWp solar array, you can generate 3,400–3,800 kWh of free electricity per year. Much of this can be used directly by the heat pump, especially with smart scheduling.

Realistically, solar might cover 30–40% of your heat pump’s annual electricity consumption, saving an additional £200–£300 per year. Your effective heating cost drops to around £450–£550/year — roughly half the cost of gas.

Gas prices are subject to the Ofgem price cap and international wholesale markets. Over the past five years, gas prices have fluctuated wildly — from 3p/kWh in 2020 to over 10p/kWh in 2022–2023.

Electricity prices are also volatile, but there is a crucial difference: with solar panels and battery storage, you can generate your own electricity. You cannot generate your own gas. This energy independence is a significant long-term advantage.

A gas boiler requires an annual service (£80–£120) and has an average lifespan of 12–15 years. A heat pump also needs an annual service (similar cost) but typically lasts 20–25 years.

Over 20 years, you are likely to need at least one boiler replacement (£2,500–£4,000), while your heat pump should still be running. Factor this in and the lifetime cost difference becomes very significant.