Heat Pump vs Oil Boiler: Why Oil Homes Should Be Switching Now
If you heat your home with oil, this might be the most important comparison you'll read. The case for switching to a heat pump is stronger for oil homes than almost anyone else, and yet plenty of people are still on oil, either through inertia or because they're worried about the disruption. Let me be direct with you: if you're on oil, a heat pump will almost certainly save you money, and there's up to £9,000 waiting for you: £7,500 from the Boiler Upgrade Scheme plus a £1,500 top-up until March 2027, because you're on oil with no mains gas connection.
Here's why this is a no-brainer for most oil homes.
The Running Cost Sum, With the Working
Start with the fuel, because that's where the argument is won. Kerosene is running at 113.52p a litre for a 1,000 litre order (BoilerJuice UK average). At 10.35 kWh a litre that's 10.97p per kWh of oil, and an 85% oil boiler turns it into 12.9p per kWh of heat in the room.
A heat pump at SCOP 3.5 on the current 26.32p electricity cap delivers heat at 7.52p per kWh. That's 58% of the oil figure, so the heat pump cuts the fuel bill by about 42%.
Put a house around it. Oil-heated homes are usually rural, detached and on the large side, so take one needing 18,000 kWh of heat a year, space heating plus hot water.
The 10-Year Cost Comparison
| Oil Boiler | Air Source Heat Pump | |
|---|---|---|
| Installed cost | £2,000–£4,000 | £9,000–£13,000 |
| Grant available | None | £7,500, plus £1,500 for oil homes with no mains gas, until March 2027 |
| Net installation cost | £2,000–£4,000 | £0–£4,000 |
| Annual fuel for 18,000 kWh of heat | £2,323 (21,176 kWh of oil at 10.97p) | £1,354 (5,143 kWh of electricity at 26.32p) |
| Annual servicing | £150–£200 | £150–£200 |
| 10-year running cost | £24,700–£25,200 | £15,000–£15,500 |
| Total 10-year cost | £26,700–£29,200 | £15,000–£19,500 |
That's roughly £970 a year on fuel and somewhere between £7,000 and £14,000 over a decade. Scale it to your own house: the saving is about 42% of whatever you currently spend on oil, whatever size you are.
Two honest caveats. The servicing figures are a quote range, not a published statistic, so we've used the same for both rather than pretending to know which is dearer. And the oil boiler replacement cost is what installers quote rather than something anyone publishes, so treat £2,000 to £4,000 as a sanity check on your own quotes. Oil prices are also genuinely volatile in a way electricity isn't, which cuts both ways: they spiked hard in 2022 and they could fall.
Oil Is Expensive and Unpredictable
This is the bit that really hurts oil users. You're at the mercy of global commodity markets. When oil prices spike (as they did in 2022), your heating bills can double almost overnight. You also need to manage deliveries, keep your tank topped up, and hope your delivery doesn't get delayed in cold weather.
With a heat pump, your heating runs on electricity. That's still not cheap, but it's regulated by the price cap and far more stable. You can fix your rate, move onto a tariff built for heat pumps, and if you have solar panels you can use your own generation during the day.
On tariffs, be precise about what you're buying. Cosy Octopus, the heat pump tariff, isn't a cheap-overnight deal: it gives three cheap windows a day (04:00 to 07:00, 13:00 to 16:00 and 22:00 to midnight) at 51% below the regional day rate, with a 16:00 to 19:00 peak at 50% above it. Intelligent Octopus Go is the overnight one, 8p a unit from 23:30 to 05:30, which suits a big cylinder and a well-insulated house that can coast. Octopus prices Cosy regionally and doesn't publish a single national rate, so check yours rather than assuming a number.
The Grant Changes Everything for Oil Homes
Here's the critical point. If your oil boiler breaks down and needs replacing, you're looking at £2,000 to £4,000 for a new one, with no grant at all. If you switch to a heat pump instead, you get £7,500 from the Boiler Upgrade Scheme, plus another £1,500 until March 2027 because gov.uk gives an uplift where the property is heated by oil or LPG and has no mains gas connection. That's £9,000 off a £9,000 to £13,000 job, so the net cost is £0 to £4,000. In a lot of cases the heat pump genuinely costs less upfront than a new oil boiler.
Let that sink in. You could spend less upfront, remove your oil tank, get off volatile fuel prices, and reduce your carbon footprint, all in one move.
What Oil Homes Need to Think About
Oil-heated homes are often rural, older, and sometimes less well-insulated than newer urban properties. That matters for heat pumps, because insulation affects how hard the heat pump has to work.
Before you install a heat pump, it's worth thinking about:
- Insulation: Is your loft insulated? Are your walls solid or cavity? A heat pump in a draughty, poorly insulated house will struggle and cost more to run. It can still work, but get your insulation sorted first if you can.
- Radiators: Heat pumps work at lower flow temperatures than boilers. You may need larger radiators in some rooms to get enough heat output. A good installer will do a heat loss calculation for every room.
- Hot water cylinder: Most heat pump systems need one. If you're on an oil boiler you very likely already have a cylinder, though it may need replacing with a bigger, better-insulated unit designed for heat pump flow temperatures. It's normally inside the quote rather than on top of it, so check which.
- Oil tank removal: You'll need to decommission and remove the tank, and there's no published figure for it because it depends on the tank, the access and whether there's contaminated ground under it. Get it priced separately rather than assuming. Some people find a home for a sound tank with a neighbour or a local farmer.
The One Reason to Hesitate
There is one scenario where switching to a heat pump right now might not make sense: if your home has genuinely terrible insulation and upgrading it would cost a huge amount (think £10,000+ for solid wall insulation across a large property). In that case, it might make more sense to do the insulation first, then install the heat pump. The heat pump will run more efficiently and cost less to run.
But even in that case, you're still better off planning for a heat pump rather than investing in another oil boiler. Get quotes for both the insulation and the heat pump, and see whether the combined cost makes sense with the grant factored in.
The Verdict: Switch Now
Oil homes have the strongest financial case for switching to a heat pump of any heating type in the UK. The running cost saving is about 42%, where a gas home switching over saves more like £170 a year. The grant is bigger, not the same: £9,000 against £7,500, because of the oil and LPG uplift. And a replacement oil boiler comes with no financial support whatsoever.
If your oil boiler is over 10 years old, start getting heat pump quotes now. Don't wait for it to break down in January. This is the most impactful change you can make to your home's running costs and carbon footprint. The economics are on your side. For help choosing a unit, see our best heat pumps UK guide and heat pump costs guide.