Boiler vs heat pump: the full picture
Replacing a gas boiler is one of the biggest decisions UK homeowners face. A new condensing gas boiler is the familiar option at £1,500 to £3,500, but gas boilers are being phased out and gas prices remain volatile. An air source heat pump costs more upfront (£7,000 to £13,000) but the £7,500 BUS grant narrows the gap considerably, and running costs can be lower in a well-insulated home.
Running costs compared
Gas costs 6.76p per kWh (Ofgem Q1 2026) and a modern condensing boiler is around 92% efficient. Electricity costs 24.5p per kWh, but a heat pump delivers 2.5 to 3.5 kWh of heat per kWh of electricity (its coefficient of performance or COP). This means the effective cost per kWh of heat is roughly 7.35p for gas and 7p to 9.8p for a heat pump, depending on efficiency. In a well-insulated home with a properly sized heat pump, running costs are comparable or lower than gas.
Why insulation matters so much
Heat pumps operate at lower flow temperatures than gas boilers (35 to 45C vs 60 to 70C). This works well in insulated homes but less efficiently in draughty ones, because the heat pump has to work harder and its COP drops. This is why we always recommend checking your insulation first and improving your EPC rating before installing a heat pump. The order matters: insulate, then install the heat pump.
Frequently asked questions
Is a heat pump cheaper to run than a gas boiler?
In a well-insulated home, yes. Despite electricity costing more per unit than gas, heat pumps are 2.5 to 3.5 times more efficient. In a poorly insulated home, a gas boiler may still be cheaper to run. Calculate your specific running costs.
How much does a heat pump cost compared to a new boiler?
A new gas boiler costs £1,500 to £3,500. An air source heat pump costs £7,000 to £13,000. The Boiler Upgrade Scheme provides a £7,500 grant, reducing the gap to roughly £0 to £2,000 in many cases.
Will gas boilers be banned?
The government plans to ban new gas boiler installations in new-build homes. For existing homes, the transition will be gradual, but gas boilers installed now will likely need replacing with a low-carbon alternative within their 15-year lifespan. A heat pump future-proofs your home.
Should I replace my boiler with a heat pump?
If your home is well insulated (or you plan to insulate it), a heat pump is usually the better long-term investment. The £7,500 grant makes it financially competitive with a new boiler, and running costs are comparable or lower. If your home is poorly insulated and you can't improve it, a gas boiler may still make more sense in the short term.