Ground Source Heat Pump vs Oil Boiler: UK Cost Comparison
Around 1.5 million UK homes still rely on heating oil -- and most homeowners dread every fill-up. Oil prices are volatile, the environmental credentials are poor, and the oil boiler ban for new installations is approaching. Ground source heat pumps offer the most efficient alternative, but the upfront cost is high. This guide gives you the full financial picture with real 2026 numbers.
See exactly how much you would save by switching from oil
Use Our Free CalculatorEnter your oil usage and property details for an instant comparison.
Running Cost Comparison
| Metric | Oil Boiler | Ground Source HP |
|---|---|---|
| Fuel cost per kWh | ~11.4p (oil) / ~13p (delivered heat) | 26.32p (elec) / ~6.9p (delivered heat) |
| Efficiency | 85-90% | SCOP 3.5-4.0 (350-400%) |
| Annual cost (15,000 kWh demand) | £1,900-£2,010 | £990-£1,130 |
| Annual cost (20,000 kWh demand) | £2,530-£2,680 | £1,320-£1,500 |
| Annual saving (20,000 kWh) | £1,150-£1,300 per year (SCOP 3.8) | |
Oil at about 117p/litre incl. VAT (BoilerJuice, October 2026, indicative), about 11.4p/kWh at 10.3 kWh/litre. Electricity at 26.32p/kWh (Ofgem cap, 1 October 2026 to 31 December 2026). GSHP SCOP 3.5-4.0 (3.8 for the saving). Heating oil is not price-capped and DESNZ figures show liquid-fuel prices up around 90% year on year, so savings move with the oil price: use your latest delivery price.
The running cost gap widens significantly if oil prices rise -- as they did dramatically in 2022. Ground source electricity costs are more stable and predictable. Homes that also install solar panels to generate their own electricity widen the gap further.
Installation Cost Comparison
| System | Installation Cost | After Grant |
|---|---|---|
| New oil boiler | £3,000-£5,000 | No grant available |
| GSHP (horizontal loop) | £15,000-£25,000 | £6,000-£16,000 |
| GSHP (borehole) | £25,000-£35,000 | £16,000-£26,000 |
"After grant" figures use the £9,000 Boiler Upgrade Scheme grant for air-to-water or ground source heat pumps replacing oil or LPG in homes without mains gas (21 July 2026 to 31 March 2027, England and Wales; £7,500 otherwise), which significantly closes the gap. No equivalent grant exists for oil boiler replacements. See the full heat pump cost breakdown.
Payback Period
The payback calculation compares the extra cost of ground source versus a new oil boiler against the annual running cost savings:
After the payback period, the ground source heat pump continues saving around £1,150-£1,300 per year at October 2026 prices for the remainder of its 20-25 year lifespan.
25-Year Total Cost of Ownership
If October 2026 prices held flat for 25 years (20,000 kWh demand), a horizontal-loop ground source heat pump would cost roughly £18,000-£43,000 less than continuing with oil. Real oil and electricity prices will move, so treat this as an illustration, not a forecast. It assumes oil boiler replacement every 12-15 years, excludes maintenance on both sides, and does not account for the ground loop lasting 50+ years, which benefits subsequent heat pump replacements.
Practical Considerations
Existing radiators: Many oil-heated homes have radiators that are large enough to work with a heat pump. Your installer will assess whether radiator upgrades are needed.
Oil tank removal: Once the heat pump is installed, you can remove the oil tank, freeing up space and eliminating the risk of oil spills and contamination. Tank decommissioning should be done by a qualified professional.
Hot water: A ground source heat pump heats your hot water just as effectively as an oil boiler. You will need a hot water cylinder (many oil homes already have one).
For a broader comparison, see our heat pump vs gas boiler guide and our assessment of whether heat pumps are worth it.
Ready to replace your oil boiler?
Request a heat pump quoteCheck if a heat pump suits your home and request a quote. No obligation.
Frequently Asked Questions
Is a ground source heat pump cheaper to run than oil?
Yes, at October 2026 prices. Ground source costs about 7p per kWh of heat at the 26.32p/kWh price cap versus about 13p for oil (around 11.4p/kWh). For a 20,000 kWh home, that is roughly £1,150-£1,300 a year. Oil prices are volatile, so check against your latest delivery price.
How much does it cost to replace an oil boiler with ground source?
£15,000-£30,000 depending on ground loop type. Homes without mains gas replacing oil get a £9,000 BUS grant until 31 March 2027, so the net cost is about £6,000-£21,000.
What is the payback period for switching from oil to ground source?
At October 2026 prices, roughly 1-11 years for horizontal systems and 9-20 years for boreholes, compared with buying a new oil boiler. Faster for larger homes with higher heat demand; slower if oil prices fall.
Can I keep my existing radiators when switching from oil to ground source?
Often yes. Many oil-heated homes already have adequately sized radiators. Your installer will assess compatibility.
Oil to Heat Pump Transition
Replacing oil boilers with heat pumps is central to the UK's decarbonisation of off-grid heating. It connects to the Boiler Upgrade Scheme, future oil boiler installation bans, and the financial case for renewable heating. Combined with solar electricity generation, the transition from oil to ground source offers off-grid homeowners both environmental and financial benefits that only improve over time.