Home Heat Pump Guide

Should I Replace My Oil Boiler with a Heat Pump?

If there is one group of homeowners who stand to benefit the most from switching to a heat pump, it is those currently heating with oil. Oil is the most expensive common heating fuel in the UK, its price is volatile and unpredictable, and oil boiler maintenance is costly. Switching to a heat pump delivers the biggest annual savings compared to any other fuel type.

For most oil boiler households, the answer to "should I switch?" is a clear yes. This guide explains why, walks through the numbers, and covers the practical steps involved.

Why Oil Boiler Homes Are the Best Candidates

The Highest Running Costs

Heating oil (kerosene) currently costs approximately 55p to 70p per litre, which translates to roughly 5.5p to 7p per kWh. At a typical boiler efficiency of 85% to 90%, the effective cost is 6p to 8p per kWh of delivered heat.

For a home needing 18,000 kWh of heat annually (oil-heated homes are often larger, rural, and less well insulated), heating oil costs approximately £1,200 to £1,600 per year.

A heat pump delivering the same heat with a seasonal COP of 2.8 (slightly conservative for these properties) uses approximately 6,400 kWh of electricity. At 24.50p/kWh, that is roughly £1,570 per year.

At first glance, the saving looks modest. But several factors swing it dramatically in the heat pump's favour.

Oil Price Volatility

Oil prices are notoriously unstable. In 2022, heating oil briefly exceeded £1 per litre — nearly doubling heating bills overnight. Unlike gas and electricity (which are regulated by the Ofgem price cap), heating oil has no price protection whatsoever. You are exposed to global crude oil markets, exchange rate fluctuations, and local supply shortages.

Electricity prices, by contrast, are capped and far more predictable. A heat pump gives you stable, budgetable heating costs.

Off-Grid Properties Get Additional Support

Many oil-heated homes are off the gas grid — exactly the properties the government most wants to decarbonise. The Boiler Upgrade Scheme grant of £7,500 applies fully to off-gas-grid properties. Some local authorities offer additional funding for rural and off-grid homes, potentially reducing costs further.

The Full Financial Picture

Installation Costs

A new oil boiler installation costs approximately £3,000 to £5,000, plus the cost of maintaining your oil tank (which must be replaced every 15 to 20 years at £500 to £1,500).

An air source heat pump installation for a typical rural property costs £10,000 to £16,000. After the £7,500 BUS grant, the net cost is £4,000 to £8,500.

The additional upfront cost compared to a new oil boiler is roughly £1,000 to £3,500 after the grant — a gap that the running cost savings close within 2 to 4 years.

Running Cost Savings

Using realistic figures for a rural four-bedroom detached house (18,000 kWh heat demand):

  • Oil boiler annual cost: £1,400 (at 65p/litre, 87% efficiency)
  • Heat pump annual cost: £1,100 (at COP 2.8, 24.50p/kWh electricity)
  • Annual saving: approximately £300

If oil prices return to 80p/litre (as they were in 2022-2023):

  • Oil boiler annual cost: £1,900
  • Heat pump annual cost: £1,100
  • Annual saving: approximately £800

With time-of-use electricity tariffs (heating overnight at 10p to 15p/kWh) and solar panels, heat pump running costs can drop to £600 to £800 per year — saving £600 to £1,100 annually compared to oil.

See our detailed running costs guide for more scenarios.

Maintenance Savings

Oil boilers need annual servicing (£150 to £250), plus you must maintain and eventually replace the oil storage tank. Heat pumps need annual servicing (£100 to £200) with no tank to worry about. The maintenance saving is £50 to £150 per year, plus the avoided tank replacement cost.

Total 15-Year Comparison

  • Oil boiler total cost (15 years): approximately £28,000 to £35,000 (including fuel, servicing, tank replacement, and one boiler replacement)
  • Heat pump total cost (15 years): approximately £22,000 to £26,000 (including installation after grant, electricity, and servicing)
  • Saving over 15 years: approximately £6,000 to £9,000

Practical Advantages Beyond Cost

No More Oil Deliveries

With a heat pump, you never need to order fuel again. No watching oil prices, no scheduling deliveries, no risk of running out during a cold snap, and no tanker needing access to your property.

Remove the Oil Tank

Once you switch, you can decommission and remove your oil tank — freeing up garden space and eliminating the risk of leaks, spills, or soil contamination (which can be extremely expensive to remediate). Your installer or a specialist contractor can handle tank removal.

Improved Property Value and EPC

An oil-heated home typically has a poor EPC rating (D or E). Switching to a heat pump, especially combined with insulation improvements, can lift your rating to C or even B. This matters increasingly as energy efficiency becomes a factor in property valuations and mortgage approvals.

Environmental Impact

Oil heating produces approximately 250 to 300g CO2 per kWh of heat. A heat pump on UK grid electricity produces roughly 50 to 70g CO2 per kWh of heat. That is a 75% to 80% reduction in carbon emissions — the biggest reduction of any boiler-to-heat-pump switch.

Cooling in Summer

Some heat pumps can provide cooling during hot weather — an increasingly valuable feature as UK summers become warmer. Your oil boiler cannot do this.

Addressing Common Concerns

"My house is old and draughty"

Many oil-heated homes are older properties. While insulation improvements help any heating system work better, a heat pump can still operate effectively in an older home. Your installer will size the system appropriately for your property's heat loss. If significant insulation work is needed, consider doing it in stages — some improvements (loft insulation, draught-proofing) are cheap and fast, while others (solid wall insulation) can be done later.

"I live in a very cold rural area"

Modern air source heat pumps work efficiently down to -15°C to -25°C. Scotland, northern England, and other cold regions have thousands of successful heat pump installations. The ground temperature for ground source heat pumps is virtually unaffected by air temperature, making them particularly well-suited to cold climates.

"I have large radiators already"

Many oil-heated homes were fitted with oversized radiators — which is actually ideal for heat pumps. A heat pump runs at lower flow temperatures than an oil boiler, and larger radiators perform better at these temperatures. You may not need to change any radiators at all. Read more in our radiator guide.

"I am worried about the electricity supply"

A heat pump typically draws 3 to 5 kW — similar to an electric oven. Most rural properties can accommodate this without a supply upgrade. Your installer will check your electrical supply as part of the survey. In rare cases where an upgrade is needed, your electricity network operator will advise on the process.

"What about power cuts?"

Your oil boiler also needs electricity to run its pump, controls, and igniter. During a power cut, neither system works. If power cuts are frequent in your area, a battery backup system can keep a heat pump running during short outages.

The Step-by-Step Process

  1. Get a survey: Request quotes from MCS-certified heat pump installers. Use our free quote service to connect with local installers
  2. Assess insulation: Your installer will identify any insulation improvements worth doing before or alongside the heat pump installation
  3. Apply for the BUS grant: Your installer applies on your behalf — the £7,500 is deducted from your invoice
  4. Installation: Typically 2 to 4 days. The heat pump is installed, connected, and commissioned. See our installation guide
  5. Oil system decommissioning: Your old oil boiler is removed and the oil tank decommissioned. Any remaining oil can often be pumped out and disposed of by the removal contractor
  6. Enjoy lower, stable bills: Your heating is now electric, predictable, and low-carbon

Frequently Asked Questions

How much will I save by switching from oil to a heat pump?

Savings depend on oil prices (which fluctuate), but typically £300 to £800 per year on fuel, plus £50 to £150 on maintenance. Over 15 years, total savings are typically £6,000 to £9,000 compared to continuing with oil.

Can I get a grant to replace my oil boiler with a heat pump?

Yes. The Boiler Upgrade Scheme provides £7,500 towards heat pump installation, regardless of whether you are replacing gas, oil, or another fuel type. Off-gas-grid properties are a priority for the scheme.

What happens to my oil tank?

Your oil tank should be professionally decommissioned and removed. This involves draining any remaining oil, cleaning the tank, and disposing of it responsibly. Costs are typically £200 to £500 and can often be included in the heat pump installation quote.

Do I need planning permission?

Most air source heat pump installations fall under permitted development and do not need planning permission. Rural properties have generous permitted development rights. Listed buildings or properties in conservation areas may need to check with the local planning authority.

Will a heat pump work with my existing heating system?

In most cases, yes. Your existing radiators and pipework can often be reused, though some radiators may need upsizing. If you have underfloor heating anywhere in your home, that is ideal for a heat pump. Your installer will assess compatibility during the survey.

Is it worth switching if my oil boiler is still working?

If your oil boiler is more than 10 years old, switching now makes financial sense because you avoid the cost of a replacement oil boiler (£3,000 to £5,000) that you would need in a few years anyway. If your oil boiler is newer than 5 years, you might wait — but monitor oil prices and the BUS grant timeline, as both could change.