Heat pump vs oil boiler: running cost and the £9,000 grant
For a typical 3-bedroom semi (about 12,000 kWh/yr), an air source heat pump (SCOP 3.5) costs about £902/yr to run versus about £933/yr for heating oil. That is about £31 saved a year. Use the calculator to put in your own home and tariff.
Running cost compared, by home size
Typical yearly running cost of an air source heat pump (SCOP 3.5) against heating oil, at the national Ofgem price cap, for five common UK homes. Every figure comes from the same model as the calculator below.
| Home | Heat kWh/yr | Oil boiler £/yr | Heat pump £/yr (cap) | Heat pump £/yr (HP tariff) | Saving/yr |
|---|---|---|---|---|---|
| 1 bed flat | 4,500 | £350 | £338 | £193 | £12 |
| 2 bed terraced house | 8,000 | £622 | £602 | £343 | £21 |
| 3 bed semi-detached house | 12,000 | £933 | £902 | £514 | £31 |
| 4 bed detached house | 19,250 | £1,497 | £1,448 | £825 | £50 |
| 5+ bed detached house | 24,000 | £1,867 | £1,805 | £1,029 | £62 |
This table assumes heating oil at 7p per kWh, an estimate rather than a live price. Heating oil is not covered by the price cap and is bought at market prices, so enter the price from your latest delivery in the calculator below for a real comparison. Homes heated by oil or LPG with no mains gas connection can get £9,000 off an air source heat pump until March 2027.
At the national price cap a heat pump undercuts heating oil on running cost once its SCOP is above about 3.4, and a typical air source heat pump runs at SCOP 3.5. Heat pump cost = yearly heat ÷ SCOP × the electricity unit price; heating oilcost = heat ÷ 0.9 boiler efficiency × the fuel price. Prices are the Ofgem cap (Oct-Dec 2026); full model in the methodology.
An estimate: heating oil is not price-capped, so enter the price from your latest delivery.
Your standard rate. The tariff scenario is shown separately.
Efficiency. 3.5 is typical.
On a standard tariff (price cap)
electricity at 26.32p/kWh
£31 /yr saved
Heat pump £902/yr · payback 72.7 yrs
On a heat pump tariff (~15p/kWh)
cheap-rate electricity
£419 /yr saved
Heat pump £514/yr · payback 5.4 yrs
Heat pump tariffs (Octopus Cosy, EDF, Scottish Power) offered off-peak rates of about 14p to 15p/kWh in June 2026. The ~15p scenario assumes most heating runs in the cheap hours.
- Now: heating oil heating
- £933/yr
- Heat pump electricity use
- 3,429 kWh/yr (~286/month)
- Indicative system size
- ~6kW
- Install after grant
- £2,250
- CO₂ saved
- 2,584 kg/yr
If you buy through links on this site we may earn a commission. It never changes the price you pay.
Estimate only. Real figures depend on your home, install and tariff. Prices: Ofgem cap, Oct-Dec 2026.
The tariff you are on matters more than the house
Every figure above uses the 26.32p/kWh price cap. A dedicated heat pump tariff runs nearer 15p in its cheap windows, roughly 43 percent off the unit rate, which moves the running cost further than any change to the property itself.