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Heat Pump vs Gas Boiler: The Complete UK Comparison 2025

Gas boilers are being phased out in UK new builds. But is a heat pump the right replacement for your home? We compare costs, efficiency, and practicalities.

📅 15 January 20259 min read
Heat Pump vs Gas Boiler: The Complete UK Comparison 2025

The Heating Landscape Is Changing

The UK government's Future Homes Standard means new homes built from 2025 will not be connected to the gas grid. With the phase-out of gas boiler sales planned for 2035, many homeowners are asking whether they should switch to a heat pump now or wait.

Efficiency

A modern condensing gas boiler achieves up to 94% efficiency — meaning 94p of every £1 spent on gas becomes heat. A heat pump achieves 300–400% efficiency (CoP 3–4), producing 3–4 kW of heat per 1 kW of electricity. However, electricity costs roughly 4× as much as gas per unit in 2025, so the running cost advantage narrows significantly.

Running Costs in 2025

With gas at approximately 7p/kWh and electricity at 24p/kWh (Ofgem averages), a typical 3-bedroom home might spend:

  • Gas boiler: £900–£1,200/year
  • Heat pump (CoP 3): £700–£1,000/year (depending on insulation and tariff)

Heat pump running costs improve significantly on an Octopus Cosy or Economy 7 tariff designed for heat pump users. As the electricity–gas price ratio normalises towards its historical average, heat pumps will become increasingly cheaper to run.

Installation Costs

A gas boiler replacement costs £2,000–£4,500 installed. An air source heat pump costs £12,000–£18,000 installed, reduced to £4,500–£10,500 after the £7,500 Boiler Upgrade Scheme grant. The higher upfront cost is the main barrier for most homeowners.

Environmental Impact

Heat pumps produce zero direct carbon emissions. When powered by the UK grid, which is now over 50% renewable, they produce significantly fewer lifetime CO₂ emissions than gas boilers. As the grid decarbonises further, this advantage grows.

Is Your Home Ready for a Heat Pump?

Heat pumps work best in well-insulated homes with underfloor heating or oversized radiators. A free heat loss survey from an MCS-accredited installer will tell you whether your property is suitable and what efficiency you can expect.

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heat pump vs boilergas boilerheating costs UKBoiler Upgrade Scheme

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