Oil to gas conversion cost in Northern Ireland.

Prices on this page are indicative ranges based on 2026 Belfast and NI installer pricing. Every installer quotes independently and the exact figure depends on your property, existing system and gas connection status.

The typical cost

A straightforward oil-to-gas conversion in a standard NI home sits in the £4,000 to £5,500 range for the installation work. Old oil tank removal typically adds £350–£500. Separately, the gas provider (Phoenix or Firmus) charges for the service connection to the street, typically £0 to £600 depending on coverage and whether a subsidy scheme is active at the time.

Total end-to-end: £4,400 to £6,600 for most domestic conversions. Larger homes with unvented cylinders for multiple bathrooms can push to £7,000+.

What's actually in the quote

• Removal of the old oil boiler and (optional) oil tank.
• New gas boiler (typically Worcester, Vaillant or Ideal combi).
• Flue, condensate drain and all pipework.
• System flush to protect the new boiler's warranty.
• Commissioning, combustion check, gas safety certificate.
• Building Control notification.
• Manufacturer warranty registration by the installer on your behalf.

The gas provider cost

Most of NI is served by Phoenix Natural Gas (Belfast, East and North). Lisburn and Western coverage is Firmus Energy. Both run periodic incentive schemes for oil-to-gas switchers:

• Phoenix sometimes waives the connection fee for standard household properties.
• Firmus runs similar schemes in their area.
• Both typically do a site survey before quoting a firm connection price.

The installer liaises with whichever provider covers your postcode, so you don't have to chase connection appointments.

Does it pay off?

Over a 10-year view, gas is usually cheaper per kWh than oil, though oil prices are volatile and sometimes dip below gas. Rough numbers:

• Typical oil-heated NI home: £1,800–£2,400/year on oil.
• Same home on gas: £1,300–£1,800/year.
• Annual saving: £300–£700.
• Payback on £4,000 conversion: 6–12 years.

That said, most people don't convert purely for financial reasons. They convert because:

• No more oil tank to fill in January when stock gets tight.
• No more dirty deliveries on the drive.
• Smaller wall-mounted gas boilers free up significant floor space.
• Gas boilers need less maintenance than oil (no annual nozzle change, no sooty heat exchanger).

Check you're on the gas network first

The first question is whether gas mains runs past your property. Phoenix and Firmus both have coverage maps; neither covers the whole of NI. In rural Antrim, Tyrone, Fermanagh and some of Down, gas isn't an option, oil or LPG are the only choices.

Send your postcode via a quote request and the installer will check coverage before quoting.