Boiler vs Heat Pump Calculator
Compare running costs of a traditional gas boiler versus a heat pump. See the long-term financial impact.
Affects heat pump efficiency (COP)
Your current annual bill
Annual Saving
£1078.13
with heat pump
Carbon Reduction
8873
kg CO2 per year
Payback Year
3
approximate
Gas Boiler
Installation Cost
£2500.00
Annual Costs
Key Specs
- Efficiency: 90%
- Lifespan: 15 years
- Emissions: 9000 kg CO2/year
- Maintenance: Annual service required
Air Source Heat Pump
Installation Cost
£13000.00
£5500.00 net
Annual Costs
Key Specs
- COP (efficiency): 3.2
- Lifespan: 25 years
- Emissions: 127 kg CO2/year
- Maintenance: Minimal (annual check-up)
10-Year Total Cost Comparison
Heat pump saves £8281 over 10 years
Gas Boiler Pros & Cons
Pros
- Lower upfront cost
- Proven, familiar technology
- No disruption to install
- Works with existing radiators
- Fast heat-up, instant hot water
Cons
- Rising gas prices (5-15% per year)
- High carbon emissions
- Needs annual maintenance
- Boiler replacement needed every 15 years
- Vulnerable to future fuel taxes/bans
Heat Pump Pros & Cons
Pros
- Lower running costs (30-50% cheaper)
- Minimal maintenance required
- 25-year lifespan (longer than boiler)
- Low carbon emissions (grid-dependent)
- Works with solar for zero-cost heat
- Future-proofs against fuel bans
- Eligibility for BUS grant (£7,500)
Cons
- Higher upfront cost (£10-13k)
- Needs outdoor unit space
- Slightly lower comfort in very cold weather
- Requires quality insulation for best results
- Slightly longer heat-up time
Which Should You Choose?
Choose Gas Boiler if:
- You need the lowest upfront cost
- You plan to move in 5-7 years
- Your property is poorly insulated
- Space is very limited for outdoor unit
Choose Heat Pump if:
- You plan to stay 10+ years
- Your property is well insulated (or you'll improve it)
- You want lower running costs and carbon emissions
- You have space for outdoor unit
- You're eligible for BUS grant
- You already have or plan solar panels
💡 Best Approach
- Improve insulation first: Better insulation increases heat pump efficiency and reduces costs
- Check BUS grant eligibility: You may qualify for £7,500 towards heat pump
- Get multiple quotes: Prices vary significantly between installers
- Consider timing: Older boilers (10+ years) are good replacement candidates
- Combine with solar: Heat pump plus solar panels = near-zero heating costs
- Plan for the long term: Gas will likely be phased out by 2035
Upfront Cost vs Running Cost
A new gas boiler costs around £2,500 installed, runs at roughly 90 percent efficiency, and costs the typical UK household £1,500 a year to heat a 3-bed semi (the calculator's default annual heating cost). A heat pump costs £10,000 to install plus £3,000 in extras (cylinder, radiators, pipework upgrade), so £13,000 total, less the £7,500 BUS heat-pump grant - net £5,500.
Running costs flip in the opposite direction. A heat pump with a coefficient of performance (COP) of 3.2, on an electricity price of 28p/kWh, runs at roughly £1,055 a year for the same heat output (£1,500 x 0.9 / 3.2 = £422 of energy at gas-equivalent terms, scaled by the electricity-to-gas price ratio). The 10-year cost gap shrinks fast: £4,000 in extra capital up front, around £450 a year saved in running, payback in roughly 9 years on average insulation.
Insulation Matters More Than COP
A heat pump in a draughty 1930s semi with single glazing performs poorly because it has to work harder to maintain the flow temperature, and the COP drops. The same heat pump in a well-insulated 2010s home delivers a real-world COP of 3.5 to 4 and runs cheaper than a gas boiler. The calculator adjusts the COP based on insulation level (poor: 2.8, average: 3.2, good: 3.5).
If you are within 2 to 3 years of a planned move, the maths usually points to a new boiler. If you are staying 7+ years and the home is reasonably insulated, a heat pump pays back. If insulation is poor, fix that first - spending £4,000 on the fabric usually saves more than spending £8,000 on the heat source. For the insulation prioritisation step, [Insulation Savings Calculator](/insulation-savings-calculator) ranks measures by payback.
Frequently Asked Questions
How much is the heat pump grant in 2026?
The Boiler Upgrade Scheme (BUS) pays £7,500 for an air source heat pump and £7,500 for ground source heat pump in England and Wales. The grant is paid to the installer who reduces the customer's bill. Scotland's equivalent is the Home Energy Scotland grant and loan, which can be more generous.
Are heat pumps cheaper to run than gas?
It depends on your tariff and your home. With a COP of 3.2 and current 2026 prices (gas 6p, electricity 28p), a heat pump runs roughly the same cost as a gas boiler. With a heat pump tariff (special heat pump electricity rates around 18p/kWh) the heat pump is 30 to 40 percent cheaper. In a poorly insulated home, a heat pump is more expensive than gas to run.
Will a heat pump work in my old house?
Yes, but it will work better with insulation upgrades first. Older houses often need bigger radiators (or underfloor heating) to deliver the same heat output at the lower flow temperatures heat pumps prefer (45 degrees C versus 70 degrees C for boilers). Budget £500 to £2,000 for radiator upgrades on top of the heat pump install.
How long do heat pumps last?
Air source heat pumps typically last 20 to 25 years, double the lifespan of a gas boiler (10 to 15 years). Ground source heat pumps last even longer (25 to 30 years for the heat pump unit, 50+ years for the ground loop). Lifecycle cost comparisons over 25 years usually favour the heat pump even before grants.
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