Are air source heat pumps really cheaper than gas?
When heat pumps can cost less to run than gas, and when headline savings depend on tariffs, efficiency assumptions or unfair boiler comparisons.
How installers usually work out running cost
They take annual heat demand (space heating plus hot water), divide by an assumed SPF or SCOP, then multiply by an electricity unit rate. Gas side uses your gas kWh and boiler efficiency.
Change the SCOP by a small amount or swap the tariff and the annual figure can move by hundreds of pounds.
When the heat pump often looks cheaper
- The quote only compares to your current boiler, which may be old or inefficient.
- A special heat-pump or time-of-use tariff is assumed.
- Low flow temperature and upgraded radiators support a higher SCOP on paper.
- Solar or battery offset is counted toward heating electricity.
When gas may still be competitive
- Standard electricity tariff with moderate SCOP.
- High flow temperatures without radiator upgrades.
- A fair comparison that includes a new condensing gas boiler with realistic install cost.
The question to keep in mind
The technology may work for your home. The quote still needs to prove the saving for your tariffs, your emitters and your alternatives.
Use your actual bills, test a standard tariff figure, and compare 10–20 year total cost (install, grant, loan, maintenance), not just year-one running cost. The Heat Pump Quote Reality Checker can help with the arithmetic.
Costs that may be missing
- Radiator or pipework upgrades
- Hot water cylinder and controls
- Electrical supply upgrades
- Redecoration after pipe runs
Common questions
Do heat pumps always beat gas on running cost?
No. At some electricity-to-gas price ratios, or with modest SCOP and high flow temperatures, gas can be competitive, especially against a new efficient boiler.
Why do two quotes show different savings?
Different heat loss, tariffs, SCOP and baseline boilers produce different results for the same house.
Related guides
Why heat pump savings claims can be misleading
Headline savings are model outputs. The assumptions behind them are what you need in writing.
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Read more →Why comparing a heat pump to an old boiler can distort the figures
If your boiler is old, almost any upgrade looks good. That does not show a heat pump beats a new gas boiler.
Read more →COP and SCOP explained in plain English
They tell you how much heat you get per unit of electricity, for stated conditions you should ask about.
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