Overview
Gas boilers burn natural gas to produce heat. Air source heat pumps extract heat from outside air and amplify it using a refrigerant cycle — producing 3–4 units of heat for every 1 unit of electricity used.
Upfront cost
Gas boiler: £999–£1,799 fitted. Air source heat pump: £8,000–£15,000 fitted (£500–£7,500 after current government grant). Gas boiler wins significantly on upfront cost.
Running costs
With gas at 7p/kWh and electricity at 28p/kWh: a heat pump at 300% efficiency costs around 9.3p/kWh — slightly more than gas. Well-insulated homes can approach gas parity.
Carbon footprint
Heat pumps produce zero direct emissions and run on increasingly green grid electricity. Gas boilers produce CO₂ directly. Heat pump wins for environment.
Practical requirements
Heat pumps work best with underfloor heating or large radiators, good wall and loft insulation, and require outdoor space for the unit. Gas boilers work in any property without modification.
Verdict
Gas boiler: right choice if your home isn't well insulated, you need an urgent replacement, or budget is constrained. Heat pump: right choice for new builds, well-insulated homes, and environmentally-motivated buyers with available grant.