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Heat Pump vs Gas Boiler Running Cost Calculator
Will an air source heat pump really cost more to run than your gas boiler? The honest sum, using this quarter's actual UK energy prices — not a sales-brochure estimate.
Tell us about your home
Estimated annual running cost
Sensitivity check: install quality decides the answer
Same home, same prices — only the heat pump's real-world efficiency (SCOP) changes.
| SCOP 2.8 poorly designed | SCOP 3.5 well designed | SCOP 4.2 excellent design |
|---|---|---|
| £0 | £0 | £0 |
The Boiler Upgrade Scheme grant (England & Wales) currently offers £7,500 off an air source heat pump installation. Running cost is only half the story — the upfront saving can change the sums completely. Check eligibility at gov.uk.
Before you decide, be honest with yourself about these
- The real answer needs a proper room-by-room heat loss survey, not a home-type average.
- Poorly insulated homes often need bigger radiators (or insulation work first) for a heat pump to run efficiently.
- Time-of-use electricity tariffs can cut heat pump running costs further — not modelled here.
- Energy prices change every quarter — re-check this calculator when your bill renews.
Who this is for
Homeowners weighing up a heat pump against a gas boiler, and the heating engineers who share this page with them to have an honest, numbers-first conversation before quoting. Everything runs in your browser — nothing you type is uploaded or stored.
Frequently asked questions
Why is electricity so much dearer per kWh, yet the sums come out close?
A gas boiler burns fuel to make heat — you get back roughly what you put in, minus a bit lost up the flue (that's the "efficiency" percentage). A heat pump doesn't create heat, it moves it: it uses electricity to run a compressor that extracts heat already present in the outside air, so for every 1 kWh of electricity it can deliver 3, 3.5 or more kWh of heat. That "over 100%" multiplier — the SCOP — is what closes the gap between an expensive fuel and a cheap one.
Will a heat pump work in an old house?
Generally yes, but the older and less insulated the house, the more the design matters. Heat pumps work best delivering a gentler, steadier heat over longer periods rather than a boiler's quick, hot blast — so an old, draughty house without insulation upgrades may need a bigger heat pump, bigger radiators, or both to hit a comfortable SCOP.
Do I need to replace my radiators?
Often, some or all of them. Heat pumps typically run at a lower flow temperature than a gas boiler, so radiators sized for boiler heat may need upsizing (or underfloor heating in places) to keep rooms warm at that lower temperature. A proper heat loss survey will tell you exactly which rooms need it.
Who can fit one?
For the £7,500 Boiler Upgrade Scheme grant, the installation must be carried out by an MCS-certified installer. It's also worth getting more than one quote — installer skill genuinely is the single biggest factor in whether your heat pump lands near the "excellent design" end of the sensitivity table above, or the "poorly designed" end. Not sure you'd qualify for the grant? Run through our Boiler Upgrade Scheme Eligibility Checker first — it takes six quick questions.
Please note: this tool gives a guide or estimate only. It may not be 100% accurate and is not professional advice — always check the figures before you rely on them. Rates, thresholds, allowances and rules can change without notice and may be out of date by the time you use this tool. Verify against HMRC / GOV.UK or your accountant before acting. Energy unit rates and the standing charge are editable — the defaults are the current Ofgem price-cap average, so check them against your latest bill or the current cap rate before relying on the result. Figures are estimates for comparison only, not a quote: get a proper heat loss survey and quote from an MCS-certified installer before deciding.
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