What the heat pump vs oil boiler running cost difference is in 2026
The most searched question is whether a heat pump or oil boiler costs less to run each year. For a typical 3-bedroom UK home using 12,000 kWh of heat per year, an air-source heat pump costs roughly £900–£1,200 annually while an oil boiler costs £1,300–£1,700. That gives an average saving of £300–£600 per year with the heat pump.
These figures come from current 2026 energy prices. Ofgem’s price cap for electricity from October to December 2026 is 24.5p per kWh (Ofgem, 2026). A modern air-source heat pump has a Seasonal Coefficient of Performance (SCOP) of 3.0–3.5, meaning it delivers 3.0–3.5 kWh of heat for every 1 kWh of electricity used. At an SCOP of 3.0, the cost per kWh of heat is roughly 8.2p. For a home needing 12,000 kWh of heat, that works out at around £980 per year.
Heating oil prices are more volatile. DESNZ’s average UK heating oil price in September 2026 was 62p per litre (DESNZ, 2026). A condensing oil boiler at 85–90% efficiency uses about 1.1 litres to deliver 10 kWh of heat. That means each kWh of heat costs roughly 6.8p from oil. On the same 12,000 kWh heat demand, the annual oil cost is around £820. However, this is a best-case calculation. In practice, oil boiler efficiency often drops to 80–85% as the system ages, and oil prices can spike. The Energy Saving Trust’s typical running cost estimates for a 3-bedroom home put oil boiler costs at £1,300–£1,700 per year, which accounts for real-world conditions and an older system (Energy Saving Trust, 2026).
So for a home using 12,000 kWh of heat, a heat pump at SCOP 3.0 costs about £980 per year. An oil boiler at 85% efficiency costs about £1,480 per year. That is a saving of £500 annually with the heat pump.
How the upfront installation costs compare for a UK homeowner
The upfront cost gap between the two systems is significant. An air-source heat pump installation for a typical 3-bedroom home costs £10,000–£15,000, according to MCS-certified installer quotes from 2026 (MCS, 2026). This price includes the indoor unit, outdoor unit, a new hot water cylinder, and necessary radiator upgrades. The Energy Saving Trust’s installation cost report for 2026 confirms this range (Energy Saving Trust, 2026).
An oil boiler replacement costs £3,000–£5,500, based on OFTEC-registered installer quotes (OFTEC, 2026). This covers a condensing boiler, standard flue, and basic controls. No hot water cylinder is needed if one already exists.
The heat pump has additional costs that the oil boiler does not. Radiator upgrades typically add £1,500–£3,000 because heat pumps run at lower flow temperatures (45–55°C versus 70–80°C for oil), so larger radiators or underfloor heating is needed to deliver the same heat. A new hot water cylinder costs £800–£1,200 if the property does not already have one. Insulation improvements may also be required, adding another £1,000–£3,000 for cavity wall or loft insulation.
Quick numbers, key decision metrics in a single table
| Metric | Heat Pump (Air-Source) | Oil Boiler (Condensing) | Source |
|---|---|---|---|
| Upfront cost (typical 3-bed home) | £10,000–£15,000 | £3,000–£5,500 | MCS installer quotes, OFTEC |
| Annual running cost (12,000 kWh heat) | £900–£1,200 | £1,300–£1,700 | Ofgem, DESNZ |
| Lifespan (years) | 15–20 | 15–20 | EST, OFTEC |
| Efficiency rating | SCOP 3.0–3.5 | 85–90% | MCS, DESNZ |
| Carbon emissions (kg CO2/year) | 1,200–1,800 | 3,200–4,000 | DESNZ carbon factors |
| Annual maintenance cost | £150–£250 | £150–£250 | EST, OFTEC |
Which system is cheaper when you account for the Boiler Upgrade Scheme grant
The Boiler Upgrade Scheme (BUS) grant changes the cost equation dramatically. From 2026, the grant for an air-source heat pump is £7,500 (GOV.UK, 2026). After the grant, the net upfront cost of a heat pump drops to £2,500–£7,500. That puts it in the same price bracket as an oil boiler replacement at £3,000–£5,500, which has no equivalent grant.
If the heat pump saves £500 per year on running costs, the payback period depends on the net cost difference. If the heat pump costs £7,500 after grant and the oil boiler costs £4,000, the extra £3,500 is recouped in 7 years. If the heat pump costs £2,500 after grant and the oil boiler costs £5,500, the heat pump is actually cheaper upfront, and the savings start immediately. The payback period ranges from 0 to 9 years for most homes.
The grant is only available for heat pumps installed by an MCS-certified installer. You must apply before installation begins. There is no grant for oil boilers under the BUS or any other scheme.
Which to choose and when
Choose a heat pump if your home has good insulation, you have space for an outdoor unit and a hot water cylinder, and you want lower running costs and carbon emissions. The Energy Saving Trust’s heat pump suitability checklist confirms that homes with cavity wall insulation, loft insulation at 300mm, and double glazing are good candidates (Energy Saving Trust, 2026). You will also need room for a 180–200 litre hot water cylinder and an outdoor unit with at least 1 metre clearance on each side.
Choose an oil boiler if your home has poor insulation that you cannot easily improve, you have limited outdoor space, or your radiators are undersized for a heat pump’s lower flow temperature. If you cannot access the BUS grant because your EPC has outstanding insulation recommendations, an oil boiler may be the only practical option in the short term. DESNZ home heating guidance notes that oil boilers remain a suitable choice for off-gas-grid homes where heat pumps are not feasible (DESNZ, 2026).
The key trade-off is this. The heat pump has lower running costs and emissions but a higher upfront cost and requires a more insulated home. The oil boiler is cheaper to install but more expensive to run and emits roughly twice the CO2.
Eligibility rules and installer certification you must check before switching
To qualify for the £7,500 BUS grant for a heat pump, your property must have an Energy Performance Certificate (EPC) with no outstanding recommendations for loft or cavity wall insulation (GOV.UK, 2026). If your EPC says you need to insulate the loft or cavity walls, you must do that work first or the grant is not available. The heat pump must be installed by an MCS-certified installer registered with TrustMark (MCS, 2026). The heat pump model must also be on the MCS product database.
For oil boilers, the installer must be OFTEC-registered (OFTEC, 2026). There is no equivalent grant. If you are switching from oil to a gas boiler instead, the installer must be Gas Safe-registered (Gas Safe Register, 2026). No grant is available for gas boilers either.
Check your EPC before you get quotes. If insulation work is needed, budget for that separately. The heat pump will not work efficiently in a poorly insulated home, and the grant will not cover it.
How the carbon footprint of each heating system compares for a UK home
The carbon footprint difference is substantial. An air-source heat pump with an SCOP of 3.5 produces 0.15 kg of CO2 per kWh of heat delivered, based on the UK grid carbon intensity of 0.15 kg CO2 per kWh of electricity in 2026 (DESNZ, 2026). A condensing oil boiler at 90% efficiency produces 0.27 kg of CO2 per kWh of heat delivered, based on the oil carbon factor of 0.24 kg CO2 per kWh of fuel.
For a home using 12,000 kWh of heat per year, the heat pump emits about 1,800 kg of CO2 annually. The oil boiler emits about 3,240 kg of CO2 annually. That is a 44% reduction with the heat pump. As the UK grid decarbonises further, the heat pump’s emissions will continue to fall. The oil boiler’s emissions are fixed.
How to improve home insulation before installing a heat pump
Boiler Upgrade Scheme 2026 full eligibility guide
Frequently Asked Questions
A heat pump costs roughly £980 per year versus £1,480 for an oil boiler on a 12,000 kWh heat demand, saving about £500 annually. These figures are based on Ofgem's 2026 electricity price cap and DESNZ's average oil price.
Yes, a heat pump is cheaper to run, saving £300–£600 per year for a typical 3-bedroom home. The Energy Saving Trust confirms oil boiler costs at £1,300–£1,700, while a heat pump costs £900–£1,200.
An air-source heat pump installation costs £10,000–£15,000 for a typical 3-bedroom home. The Boiler Upgrade Scheme offers a £7,500 grant to reduce this upfront cost.
An oil boiler installation costs £3,000–£5,000 for a standard system. This is significantly less than a heat pump but does not qualify for the Boiler Upgrade Scheme grant.
A heat pump lasts 15–20 years, while an oil boiler typically lasts 10–15 years. Heat pumps also require less annual maintenance, with costs around £150–£200 per service.
