How much does it cost to change from oil to gas heating in Northern Ireland?

The researched NI 2026 range for a full oil-to-mains-gas conversion is £3,500 to £6,500, typically over three to five days. That covers the switch as a package: connecting the property to the gas main, the new gas boiler, and the pipework changes to serve it, with your existing radiators usually staying put. What moves you within the range is mostly the connection itself (distance from the main and where the meter goes), where the new boiler is sited relative to the old one, and whether the survey turns up pipework or controls that need bringing up to standard at the same time.

Availability is the first gate, and in Northern Ireland it rules most homes out before price enters it. Roughly two thirds of NI homes heat with oil, and mains gas only exists where the Phoenix or Firmus network has been laid. So the first call is not to a heating engineer, it is to the network operator for your area to confirm your street has gas at all. Worth knowing on incentives: Phoenix Natural Gas ran a commercial cashback of up to £600 toward a new gas boiler whose advertised offer ended on 30 June 2026, so check directly for any current offer, and remember those are energy-company offers rather than government grants.

Whether it is worth it is really a comparison against your alternatives. A like-for-like oil boiler swap on your existing tank and pipework runs £2,500 to £4,500, so the conversion premium is £1,000 to £2,000 and you should weigh that against the running-cost difference, which moves with fuel prices rather than sitting still. If your oil tank is also due for replacement the maths shifts toward converting, since boiler plus new bunded tank runs £4,000 to £6,500 on the oil side. And a conversion is a legal dividing line for who can do the work: the gas side must be done by a Gas Safe registered engineer, not the OFTEC engineer who serviced your oil boiler, and once you are on gas the annual service changes too, with landlords needing a gas safety certificate every 12 months.

Before accepting any conversion quote, sanity-check it against the researched NI ranges with our free Quote Checker, and read the full oil boiler replacement guide linked below for the complete cost table this answer draws from, including the tank, flue and full-system scenarios on the oil side.