Heat Pump vs Gas Boiler UK 2026 — Cost, Running Cost & Carbon Compared
This is the question almost every UK household with a gas heating system asks in 2026, and there isn't one right answer. Whether a heat pump or a gas boiler is the better choice for you depends on your home, your fuel, your tariff, and how long you'll live there. Here's the honest comparison — and the cases where each option genuinely wins.
Install cost compared
| System | Install cost (typical home) | Grants available | Net cost |
|---|---|---|---|
| Combi gas boiler (replace existing) | £2,500–£3,500 | None for like-for-like | £2,500–£3,500 |
| System gas boiler with cylinder | £3,500–£5,000 | None for like-for-like | £3,500–£5,000 |
| Air source heat pump (typical home) | £10,000–£13,000 | £7,500 BUS (£9,000 oil/LPG from July 2026) | £2,500–£5,500 |
| Ground source heat pump (trench) | £20,000–£28,000 | £7,500 BUS | £12,500–£20,500 |
| Air-to-air heat pump | £4,000–£8,000 | £2,500 BUS | £1,500–£5,500 |
The eye-catching number: after BUS, a typical air source heat pump install can be cheaper than a top-spec system boiler. For oil/LPG households waiting for July 2026's £9,000 BUS uplift, the heat pump is regularly cheaper to install than the replacement boiler would have been.
Running cost compared
The thing most people get wrong about this comparison: it's not about gas-cost-per-kWh vs electricity-cost-per-kWh. It's about cost-per-kWh-of-heat-delivered.
At Ofgem Q2 2026 prices (gas 6.3p/kWh; electricity 24.5p/kWh on standard cap):
| System | Efficiency | Cost per kWh of heat (standard cap) | Cost per kWh of heat (smart tariff) |
|---|---|---|---|
| Gas combi boiler | ~88% (90% nameplate) | 7.0p | n/a |
| Gas system boiler with cylinder | ~85% (some standing losses) | 7.4p | n/a |
| Oil boiler | ~85% | 8.5–10.5p (varies with oil price) | n/a |
| LPG boiler | ~85% | 10.5–13.5p | n/a |
| Heat pump (SCOP 2.9, UK average) | 290% | 8.4p | ~5.1p (Cosy) |
| Heat pump (SCOP 3.4, well-insulated) | 340% | 7.2p | ~4.4p (Cosy) |
| Heat pump (SCOP 4.0, ground source well-tuned) | 400% | 6.1p | ~3.7p (Cosy) |
Translating to typical annual heating cost (12,000 kWh of heat for a UK semi):
| System | Annual cost | Standing charge | Total |
|---|---|---|---|
| Gas combi (cap) | £840 | £117 | £957 |
| Oil boiler | £1,140 | n/a | £1,140 + oil delivery costs |
| LPG boiler | £1,440 | n/a | £1,440 + LPG delivery costs |
| Heat pump (SCOP 2.9, cap) | £1,008 | (included in electricity) | £1,008 |
| Heat pump (SCOP 2.9, Cosy) | £612 | (included) | £612 |
| Heat pump (SCOP 3.4, Cosy) | £528 | (included) | £528 |
| Heat pump (SCOP 4.0, Cosy) | £444 | (included) | £444 |
Key observations from this data:
- On the standard cap, a UK-average-SCOP heat pump costs ~£50/year more than gas — basically a tie.
- On Cosy Octopus, the same heat pump beats gas by £345/year.
- For oil and LPG households, heat pumps win on the cap by £100–£400/year and on Cosy by £500–£800/year. This is why the BUS oil/LPG uplift to £9,000 makes such strong sense.
- A well-insulated home with a tuned heat pump on Cosy saves £429/year vs gas.
What would your specific saving be? Our running cost calculator uses your home's actual fuel use and runs the maths against four tariff options.
Try the calculator →15-year total cost of ownership
Putting install + running together over a typical 15-year horizon (gas boiler life is 10–15 years; heat pump life is 15–20 years):
| Scenario | Install | 15× running cost | Replacement | 15-year total |
|---|---|---|---|---|
| Gas boiler (cap, replacement at year 12) | £3,000 | £14,355 | £3,500 mid-period | £20,855 |
| Heat pump (SCOP 2.9, Cosy) | £4,000 (after BUS) | £9,180 | None | £13,180 |
| Heat pump (SCOP 3.4, Cosy) | £4,000 | £7,920 | None | £11,920 |
| Heat pump (SCOP 2.9, cap) | £4,000 | £15,120 | None | £19,120 |
| Oil boiler (oil at 9p/kWh of heat) | £3,500 | £17,100 | £3,500 mid-period | £24,100 |
| Heat pump replacing oil (SCOP 2.9, Cosy, July 2026 £9k BUS) | £2,500 (after £9k BUS) | £9,180 | None | £11,680 |
On a 15-year basis:
- Heat pump on Cosy vs gas: heat pump saves £7,675–£8,935.
- Heat pump replacing oil (post-July 2026): heat pump saves £12,420 vs continuing with oil.
- Heat pump on standard cap (no smart tariff): roughly breakeven with gas. This is the case in which the heat pump doesn't pay back — and it's why we tell people not to install one without switching tariff.
Carbon footprint compared
A typical UK home heated by gas emits about 2,000 kg of CO₂ per year from heating alone. A heat pump using grid electricity emits about 500 kg (and falling, as the UK grid decarbonises). Over a 15-year heat pump life, that's roughly 23 tonnes of CO₂ avoided per household.
The carbon-per-kWh of UK electricity has fallen from ~500g CO₂/kWh in 2010 to ~190g in 2025 to forecast ~110g by 2030 (per NESO). Heat pump carbon emissions fall automatically as the grid cleans up; gas boiler emissions don't.
From 2035, gas boilers cannot be installed in new homes (Future Homes Standard) and a phase-out of new gas boiler sales is confirmed for 2035 across the UK. If you're installing in 2026, you're either choosing a heat pump now or replacing your boiler again before the phase-out.
When each option clearly wins
Heat pump wins clearly when…
- You're currently on oil or LPG. Heat pump beats both significantly on running cost. With the July 2026 £9,000 BUS, payback is 3–6 years.
- Your home has at least decent insulation (EPC C or above, or insulation upgrades planned via WHLG/ECO4).
- You can switch to a smart tariff (Cosy Octopus, EDF Heat Pump Tracker).
- You'll stay 8+ years in the home.
- You care about lifetime carbon.
- Your existing boiler is at end of life — meaning you're replacing it anyway. The marginal cost of going heat pump vs boiler at this moment is small.
Gas boiler still makes sense when…
- You live in a poorly insulated old home you're not going to insulate. A heat pump in a leaky home means SCOP 2.3 and high running costs.
- You're moving in 1–2 years. Heat pump payback is too long to make the install worth it before you sell.
- The BUS grant isn't available to you (you've already claimed at the property; or you live in a property type that's not eligible). Without the grant, payback stretches to 15+ years.
- You're not willing to switch tariff. Heat pump on standard cap is a wash.
- Your home can't physically fit a hot water cylinder (some flats; some combi-boiler homes with no airing cupboard or loft space). Air-to-air may still work; full air-to-water won't.
The 1–5 year outlook
Three things are working in the heat pump's favour over the next 5 years:
- Heat pump install prices are falling. Octopus, Aira and BOXT have all introduced fixed-price quoting models that have pulled the median ASHP install price down ~10% in the last 2 years. The Clean Heat Market Mechanism (boiler manufacturer obligation) is also adding ~£36 to boiler prices to fund subsidies for heat pumps.
- UK electricity is decarbonising and gas is becoming more expensive. The UK grid carbon intensity is falling toward 110g CO₂/kWh by 2030 (from 190g in 2025). UK gas prices are structurally exposed to global LNG markets that are trending higher.
- The smart tariff ecosystem is maturing. Cosy, EDF Tracker and forthcoming products will offer better terms as grid flexibility becomes more valuable. Heat pump tariffs in 2030 will likely give 40–50% running cost savings vs the standard cap, not the current 25–35%.
The single argument against waiting: 0% VAT reverts to 5% on 31 March 2027. On a £12,000 install that's a £600 swing. Combined with the July 2026 £9,000 BUS for oil/LPG, the window for the very best total economics for off-gas households is roughly July 2026 – March 2027.
Explore more
- Main heat pump pillar — full guide.
- Heat pump cost UK 2026 — detailed cost breakdown.
- How heat pumps work — the physics.
- Running cost calculator — your specific numbers.
- BUS deep dive — including July 2026 £9,000 uplift mechanics.
Frequently asked questions
Will a heat pump definitely save me money?
Only if you can switch to a heat pump tariff (Cosy / EDF Tracker) and your insulation is reasonable. On the standard cap with a poorly insulated home, a heat pump can cost slightly more to run than gas. The right answer depends on your specific scenario — use our calculator.
How long does a gas boiler last?
10–15 years for a modern condensing combi; 15+ years for higher-end system boilers with proper servicing. The 2035 new-installation phase-out doesn't affect existing boilers — you can keep yours running as long as you can get it serviced and parts.
Is gas going to get banned?
The UK has confirmed a 2035 phase-out of new gas boiler installations. Existing boilers can continue indefinitely. Gas networks are likely to continue operating into the 2040s, with grid hydrogen blending being trialled in some regions.
What happens to my gas standing charge if I install a heat pump?
If you keep your gas supply (for the hob, or as a backup), you keep paying the gas standing charge (~£117/year). If you disconnect from gas entirely, you save it — but disconnection costs around £200–£400 to physically have the supplier cap the supply.
What if my heat pump breaks down in winter?
Most heat pumps have a built-in immersion-element backup that kicks in if the heat pump fails. It's expensive to run (essentially 100% efficient electric heating, no COP advantage) but it keeps you warm. Most warranty and service contracts include 24-hour winter callout.
Can I keep my gas boiler as backup?
Not as a "hybrid" if you want the £7,500 BUS — hybrid systems aren't eligible. You can keep gas for hob and a stand-alone water heater, but the BUS pump must be the primary central heating system.
Sources
- BUS — Energy Saving Trust
- Q2 2026 energy price cap — Ofgem
- Cosy Octopus heat pump tariff
- Britain's Energy 2025 Review — NESO
- Heat pump savings calculator — Heat Geek
Page changelog
- 19 May 2026 — Initial publication. Reflects Q2 2026 cap of £1,641, July 2026 BUS oil/LPG uplift, current Cosy / EDF Tracker pricing, and the EST 742-home SCOP field trial.
See your specific comparison
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