The heat pump now lands at roughly the same upfront cost as a new gas combi after the grant. There is effectively no upfront premium to recover, so the comparison now comes down to running costs and lifespan.
Annual running cost comparison (2026 prices)
These figures use 2026 average tariffs: gas at 6.5p/kWh + standing, electricity at 28p/kWh standard tariff or 15p effective on a heat-pump tariff like Octopus Cosy.
| Annual cost | New gas combi | Heat pump (standard tariff) | Heat pump (heat-pump tariff) |
|---|---|---|---|
| Heating fuel use | 13,500 kWh gas | 3,550 kWh elec (SCOP 3.8) | 3,550 kWh elec (SCOP 3.8) |
| Heating fuel cost | £878 + standing charge ~£110 | £994 | £533 |
| Service plan | £180/year | £240/year | £240/year |
| Total annual running cost | ~£1,168 | ~£1,234 | ~£773 |
| Annual saving vs gas | — | −£66 (gas slightly cheaper) | +£395 (heat pump cheaper) |
Two important things to notice:
- On a standard electricity tariff, the heat pump runs roughly the same as gas, so the saving only really shows up on a heat-pump tariff.
- On a heat-pump tariff (Octopus Cosy or equivalent), the heat pump saves ~£400/year — and with no upfront premium to recover, that is a saving from year one.
The tariff choice is the single biggest variable in this whole comparison. Thermova helps every customer switch to an appropriate heat-pump tariff at handover. 10-year total cost of ownership Adding upfront + 10 years of running costs gives the headline number most homeowners actually care about:
| 10-year total | Gas combi | Heat pump (standard tariff) | Heat pump (heat-pump tariff) |
|---|---|---|---|
| Upfront (after grant) | £3,500 | £3,200 | £3,200 |
| 10 years of running | £11,680 | £12,340 | £7,730 |
| Mid-life part replacements | ~£800 (pumps, valves) | ~£600 (filters, sensors) | ~£600 |
| 10-year total cost of ownership | ~£15,980 | ~£16,140 | ~£11,530 |
On a heat-pump tariff, the heat pump comes out roughly £4,450 cheaper than the gas combi over 10 years (£11,530 vs £15,980). On a standard tariff, the two are line-ball — the heat pump costs only about £160 more over 10 years (£16,140 vs £15,980). Then year 11 onwards, the heat pump diverges sharply in its favour: the boiler is end-of-life and needs replacing (~£3,500), while the heat pump has another 10+ years left. Sensitivity: what if gas prices rise? The numbers above assume gas prices stay roughly flat in real terms over 10 years. That is the optimistic case for gas. Two scenarios that change the maths:
- Gas prices rise 4% above inflation per year (broadly consistent with 2020–2025 trend): the heat pump (on a heat-pump tariff) is roughly £7,600 cheaper than gas over 10 years.
- Carbon pricing extends to gas heating (proposed but not legislated; pencilled into HM Treasury modelling): heat pump pulls further ahead, by roughly £9,000+ over 10 years.
The structural direction of UK energy policy is toward more expensive gas and cheaper renewable electricity. Betting on gas costing the same in 2036 as 2026 is the bet most analysts wouldn’t take.
Carbon footprint comparison
For households where carbon matters — and it does for an increasing share of buyers when you come to sell — the gap is much wider than the cost gap:
| Carbon metric | Gas combi | Heat pump |
|---|---|---|
| Annual CO₂ from heating | 2,470 kg | 685 kg |
| 10-year CO₂ from heating | 24,700 kg (24.7 tonnes) | 6,850 kg (6.85 tonnes) |
| Annual CO₂ saved | — | 1,785 kg (−72%) |
And as the UK grid keeps decarbonising (current trajectory is roughly halving by 2035), the heat pump’s carbon footprint keeps falling automatically. The gas boiler’s carbon footprint doesn’t.
When a heat pump wins decisively
Some Lancashire homes are no-brainer heat pump cases. If yours hits two or more of these, install a heat pump:
- You’re off mains gas (oil, LPG, or electric heating) — savings often £1,500+/year, payback under 7 years
- Your home is reasonably well insulated (EPC C or D, loft and floor at minimum)
- You have outdoor space for a unit roughly washing-machine-sized
- You’re willing to switch to a heat-pump electricity tariff at handover
- You plan to be in the property 8+ years (longer ownership = bigger lifetime saving)
- You’re combining with solar PV and a battery (Thermova’s whole-home route shifts the maths further)
When a gas boiler still makes sense
Heat pumps aren’t always the answer. Be honest about which case you’re in:
- You’re selling in 1–3 years and have no urgent need to improve EPC for sale — the running-cost saving won’t have time to add up before you move
- Your home is very poorly insulated (EPC F or G) and you have no plan to upgrade — heat pumps perform poorly on uninsulated leaky homes
- You have no outdoor space for an outdoor unit (small flats, certain terraces with no rear access)
- You won’t switch tariffs for whatever reason — the heat-pump case is much weaker on a standard tariff
- You’re replacing a boiler in an emergency with no time for a heat-pump survey and BUS application — a gas combi as a stop-gap, then plan the heat pump for next year, is sometimes the pragmatic answer
When a hybrid heat pump might be the answer
A hybrid system keeps your gas boiler as cold-weather backup and pairs it with a smaller heat pump that does 80–90% of the annual heating. The maths is genuinely competitive for:
- Older Lancashire properties with high heat demand at design temperature (typically pre-1930 solid wall)
- Homes where a single large heat pump won’t fit the available outdoor space
- Homes where the upfront cost of the full heat pump conversion is the blocker — hybrids come in roughly £1,000 cheaper
Hybrids are also BUS-grant-eligible at the same £7,500 rate. Thermova quotes hybrid as an option alongside the full heat pump where the property suggests it.