Total Cost of Ownership: Heat Pump vs Gas Boiler Over 20 Years
Comparing a heat pump to a gas boiler on installation cost alone is like comparing a Tesla to a petrol car based on the sticker price. Over 20 years, a heat pump with the BUS grant and a TOU tariff costs £31,200 total -- saving £7,150 compared to the gas boiler's £38,350. Even on a standard tariff, the two systems cost virtually the same.
This guide calculates the complete 20-year cost for both systems in a typical UK home. No cherry-picked figures. For installation costs alone, see our cost guide. For the broader comparison, see heat pump vs gas boiler.
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Our Baseline Assumptions
| Property | 3-bed semi, 12,000 kWh annual heat demand |
| Gas boiler efficiency | 92% |
| Heat pump seasonal COP | 3.0 |
| Gas rate | 6.76p/kWh |
| Electricity rate | 24.50p/kWh |
| Annual inflation | 3% for both fuels |
| BUS grant | £7,500 |
Installation Cost
The difference is just £1,300 after the grant. Without the grant, the gap is £8,800. See our full cost breakdown.
Annual Running Costs (Year 1)
Gas boiler: £999/year (£882 fuel + £117 standing charge). Heat pump: £980 standard / £863 with gas standing charge saved. At current prices, running costs are remarkably similar. See our running costs guide.
Maintenance and Replacement
Gas boiler: £175/year average, plus replacement at year 13 (~£4,800). Heat pump: £155/year average, potential compressor replacement at year 18 (~£4,250). Fewer moving parts and no combustion components give heat pumps a slight maintenance edge.
The 20-Year Total Cost Comparison
With the grant and a TOU tariff, the heat pump saves £7,150 over 20 years. Without the grant, the gas boiler is cheaper. This is why the BUS grant matters so much.
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What Could Change the Numbers
Energy price rebalancing: If electricity levies shift to gas bills, the heat pump saves an additional ~£510 per year. Gas boiler ban effect: From 2035, maintenance costs may rise. Carbon pricing: Even a modest £50/tonne CO2 adds ~£100/year to gas bills.
Properties with solar panels can further reduce the heat pump's electricity costs, widening the gap in the heat pump's favour.
For a broader assessment beyond pure cost, our are heat pumps worth it guide covers the full picture. Use our suitability checker to confirm your home is suitable.
Frequently Asked Questions
Is a heat pump cheaper than a gas boiler over 20 years?
With the BUS grant and standard rates, roughly equal. With a TOU tariff, the heat pump saves ~£7,000. Without the grant, gas is cheaper.
How long does it take for a heat pump to pay for itself?
With BUS grant and TOU tariff, approximately 4-6 years from gas. From oil or LPG, 3-5 years even at standard rates.
What if energy prices change dramatically?
If electricity gets cheaper relative to gas (as intended), the heat pump wins decisively.
Should I wait for heat pump prices to drop?
Acting while the £7,500 grant is available is usually financially sensible.
What about hydrogen boilers?
No UK hydrogen grid exists. Basing a 20-year decision on hydrogen availability would be speculative.
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About this guide: This article provides a comprehensive 20-year cost comparison between heat pumps and gas boilers. For most UK homes, the BUS grant makes a heat pump cost-competitive over its lifetime. Combining with solar panels further tilts the economics in the heat pump's favour by reducing electricity costs.