HeatPumpHeat Pump vs Oil Boiler — The Clearest Case for Switching
If there's one heating switch that's an absolute no-brainer, it's this one. Oil costs £1,800 or more per year to run. A heat pump costs £800-£1,200. Add the £7,500 BUS grant, and most oil-heated homes can switch for under £5,000 out of pocket while saving £600+ every single year. Here's the full picture.
Bottom line: switching from oil to a heat pump saves £600-£1,500/yr
With the BUS grant covering £7,500 of the installation cost, payback is typically 3-5 years. After that, it's pure savings — and you never have to worry about oil deliveries or price spikes again.
Head-to-Head Comparison
| Factor | Heat Pump (ASHP) | Oil Boiler | Winner |
|---|---|---|---|
| Installation cost | £10,000 – £15,000 | £3,000 – £5,000 | Oil boiler |
| After BUS grant | £2,500 – £7,500 | No grant available | Heat pump |
| Annual running cost | £800 – £1,200 | £1,800 – £2,500 | Heat pump |
| Running cost (off-peak tariff) | £281 – £375 | £1,800 – £2,500 | Heat pump |
| Price stability | Electricity regulated by Ofgem | Oil prices highly volatile | Heat pump |
| Maintenance | £100 – £200/yr | £100 – £250/yr + tank inspection | Similar |
| Lifespan | 20 – 25 years | 15 – 20 years | Heat pump |
| Carbon emissions | ~0.7 tonnes CO2/yr | ~3.5 tonnes CO2/yr | Heat pump |
| Smell / mess | None | Oil smell, tank in garden, delivery access | Heat pump |
| Government support | £7,500 BUS grant + 0% VAT | None — likely phase-out coming | Heat pump |
Running Cost Breakdown
Oil heating is expensive. Here's why the numbers are so different:
Oil boiler: ~£1,800 – £2,500/yr
- Typical 3-bed home uses 1,500 – 2,000 litres of kerosene per year
- Current price: ~65-80p/litre (highly variable)
- Oil boiler efficiency: ~85%
- At 70p/litre and 1,800 litres: £1,260 in fuel alone, plus standing charge and delivery
- Larger or draughtier homes easily exceed £2,000/yr
Heat pump: £281 – £918/yr (depending on tariff)
- Same home needs 12,000 kWh of heat
- Heat pump COP 3.2 = 3,750 kWh electricity used
- At standard rate (24.5p): £918/yr — saving ~£900/yr vs oil
- At Economy 7 (10p): £375/yr — saving ~£1,400/yr vs oil
- At Octopus Cosy (7.5p): £281/yr — saving ~£1,500/yr vs oil
Even at the worst-case standard electricity rate, a heat pump saves roughly £600 to £900 per year compared to oil. On an off-peak tariff, you're saving £1,200 to £1,500 per year. For full tariff calculations, see our running costs guide.
Payback Period
With the £7,500 BUS grant, the upfront cost of switching from oil to a heat pump is typically £2,500 to £7,500 — less than many people expect. Here's how quickly it pays back:
| Scenario | Net Cost After Grant | Annual Saving vs Oil | Payback |
|---|---|---|---|
| Small home, standard rate | £2,500 | ~£700 | 3.5 years |
| Medium home, standard rate | £5,000 | ~£900 | 5.5 years |
| Medium home, off-peak tariff | £5,000 | ~£1,400 | 3.5 years |
| Large home, off-peak tariff | £7,500 | ~£1,500 | 5 years |
After payback, you're saving £700-£1,500 every year for the remaining 15-20 years of the heat pump's life. Over 20 years, the total saving compared to staying on oil is typically £12,000 to £25,000.
Dealing with Your Oil Tank
Once you switch, you'll want to remove the old oil tank. Here's what's involved:
- Decommissioning: A registered technician drains any remaining oil and disconnects the tank from the boiler. Cost: £200-£400.
- Tank removal: Plastic tanks can be cut up and removed easily. Steel tanks may need a crane or cutting equipment. Total removal cost: £300-£800.
- Soil testing: If the tank has leaked or there's staining around it, you may need soil testing and remediation. This can cost £500-£3,000 for contaminated sites — but most domestic tanks are fine.
- The upside: You get your garden space back, eliminate the oil smell, remove a fire/pollution risk, and never need to worry about oil delivery access again.
Many heat pump installers can coordinate tank removal as part of the overall project, or recommend a local specialist. Budget £500-£1,500 for tank removal and decommissioning in most cases.
Environmental Impact
Oil is one of the dirtiest ways to heat a home. Switching to a heat pump delivers a dramatic carbon reduction:
- Oil boiler: ~3.5 tonnes CO2 per year (for a typical 3-bed home)
- Heat pump: ~0.7 tonnes CO2 per year (using current UK grid electricity)
- Reduction: ~80% fewer carbon emissions from day one
- As the UK grid continues to decarbonise (renewables now exceed 50% of generation), the heat pump's carbon footprint will fall further. By 2030, it could be near zero.
Beyond carbon, oil boilers produce local air pollutants (NOx, particulates) and carry a risk of fuel spills contaminating soil and groundwater. Heat pumps produce zero local emissions.
How the Switch Works
- Get quotes from MCS-certified installers — ask specifically about oil-to-heat-pump conversions. Not all installers have experience with this. See our choosing an installer guide.
- Survey and system design — the installer assesses your home's heat loss, checks radiator sizes, and designs the system. They will also check if your electrical supply can handle the heat pump (most can).
- BUS grant application — your installer applies to Ofgem for the £7,500 grant. See our BUS grant guide for the full process.
- Installation (2-5 days) — the outdoor unit is fitted, the indoor unit and cylinder installed, and the system connected to your existing pipework. Some radiators may be swapped out.
- Oil system decommission — the old boiler and oil tank are removed (can be done during or after the heat pump install).
- Commissioning and handover — the installer sets up the system, shows you how to use it, and registers it with MCS.
Related Guides
BUS Grant Guide
How to claim the £7,500 grant for your heat pump.
Installation Costs
Full cost breakdown for ASHP and GSHP.
Running Costs
Annual cost at every electricity tariff.
Heat Pump vs Gas Boiler
The gas comparison is more nuanced — read it here.
Frequently Asked Questions
How much will I save switching from oil to a heat pump?
Most households save £600 to £1,200 per year on running costs. Oil heating typically costs £1,800 to £2,500/yr depending on usage and oil prices. A heat pump costs £800 to £1,200/yr at standard electricity rates, and as little as £281/yr on Octopus Cosy tariff.
Can I use my existing radiators with a heat pump?
Often yes. Heat pumps run at lower flow temperatures (35-45°C vs 60-80°C for oil boilers), so some radiators may need upsizing. A good installer will do a room-by-room heat loss calculation. Many oil-heated homes have oversized radiators already, which actually helps.
What happens to my oil tank?
You will need to decommission and remove the oil tank. This typically costs £500 to £1,500 depending on size, location, and whether soil testing is needed (required if there has been any leakage). Your heat pump installer can usually arrange this or recommend a specialist.
Is the BUS grant available for replacing oil boilers?
Yes. The £7,500 BUS grant is available for any existing property in England and Wales, regardless of your current fuel type. In fact, off-gas-grid properties replacing oil boilers are one of the most common BUS grant applications.
Will a heat pump work in a rural property?
Yes. Heat pumps work in any UK location. Air source heat pumps are effective down to -15°C and modern units are designed for the UK climate. Rural properties are often ideal candidates because they tend to have space for the outdoor unit and are already off the gas grid.
What about oil price volatility?
Oil prices are notoriously volatile. In 2022, heating oil peaked at over 90p/litre before falling back. Electricity prices are regulated by the Ofgem price cap and are far more predictable. Switching to a heat pump removes your exposure to oil market fluctuations entirely.