If you’re a homeowner in Northern Ireland with an oil boiler, two live grant schemes may apply in 2026: the NIHE Boiler Replacement Scheme (up to £1,700) and the NI Sustainable Energy Programme (NISEP, variable). They can be used to replace an old oil boiler with a new oil boiler, or to switch from oil to gas entirely.
Here’s what each covers, who qualifies, and the order to apply in.
The two main schemes for oil homeowners
1. NIHE Boiler Replacement Scheme
- Maximum grant: £1,700 (household income under £40k), £1,000 (under £60k)
- Existing boiler: 15+ years old
- Applies to: owner-occupiers
- Covers: new condensing boiler (oil, gas, LPG or wood pellet)
- Installer must be: OFTEC registered for oil, Gas Safe for gas
- Grant paid to: installer, not homeowner
Full details: Boiler Replacement Scheme NI.
2. NI Sustainable Energy Programme (NISEP)
- Run through: energy suppliers (Power NI, SSE Airtricity, Budget Energy, Click Energy)
- Income tested: low-income households, benefits, fuel poverty
- Covers: boiler replacement, insulation, oil-to-gas conversion
- Grant amount: variable, sometimes up to 100% of cost for qualifying households
- Apply: through your energy supplier directly
Which to choose
The honest comparison:
| Your situation | Best route |
|---|---|
| Oil boiler 15+ years old, household £40-£60k | NIHE Boiler Replacement (£1,000) |
| Oil boiler 15+ years old, household under £40k | NIHE Boiler Replacement (£1,700) |
| Low-income / on benefits, oil boiler any age | NISEP (often pays more) |
| Low-income, switching oil-to-gas | NISEP + PNG connection grant |
| Pensioner on limited income, oil heating | NISEP + Warm Home Discount |
| Higher-income, oil boiler under 15 years | Neither (not eligible) |
You can only claim from ONE boiler-replacement scheme, so pick whichever pays more. You CAN additionally claim PNG connection grants (Phoenix Natural Gas grants) alongside either, since that’s the gas supply side rather than the boiler side.
Oil-to-oil replacement: still grant-eligible?
Yes. NIHE Boiler Replacement Scheme covers like-for-like oil replacement, as long as the new boiler is a condensing oil boiler meeting minimum efficiency.
Typical Belfast oil-to-oil replacement cost:
| Item | Typical range |
|---|---|
| New condensing oil boiler (Grant, Warmflow, Firebird) fitted | £2,400-£3,800 |
| Oil line renewal | £120-£220 |
| Tank gauge and filter renewal | £85-£140 |
| Minor system flush | £180-£280 |
| Commissioning + OFTEC cert | included |
| Gross total | £2,800-£4,400 |
| Less NIHE grant (up to £1,700) | |
| Net out-of-pocket | £1,100-£2,700 |
See Oil Boiler Servicing for current-boiler care before replacement becomes urgent.
Oil-to-gas switch: the bigger picture
Many homeowners consider using the grant to switch to gas rather than replace oil-to-oil. The maths:
| Route | Gross cost | After grants (NIHE + PNG) | Annual running cost saving |
|---|---|---|---|
| Oil-to-oil replacement | £2,800-£4,400 | £1,100-£2,700 | £100-£250 |
| Oil-to-gas conversion | £4,500-£8,500 | £2,800-£6,800 | £450-£900 |
Payback on the extra conversion cost: usually 4-7 years. Full maths: Oil to gas conversion cost NI.
Reasons to stay on oil: outside the PNG network, large heat load with bulk oil contract, listed property with flue restrictions.
Reasons to switch: in-network, oil boiler 12+ years old, staying 5+ years.
Application order
- Check NIHE eligibility at nihe.gov.uk (5-minute form)
- Check your energy supplier for NISEP — often more generous if you qualify
- Pick the better of the two
- If switching to gas: also check PNG network coverage at your address (energiani.com)
- Apply to your chosen scheme
- Wait for offer letter
- Get installer quotes against the offer
- Book the install
Don’t apply to both NIHE and NISEP hoping to stack, you can’t. Both will ask whether you’ve applied to the other, and both will check.
What we do
We are OFTEC registered for oil boilers and Gas Safe registered for gas. On a scheme install we:
- Quote against the grant offer letter inside 48 hours
- Handle direct invoicing to NIHE where applicable
- Remove and dispose of the old boiler safely
- Commission the new boiler and issue the OFTEC / Gas Safe certificate
- Register the boiler for warranty
Areas covered: Belfast, Lisburn, Newtownabbey, Bangor, Ballymena, Carrickfergus, Newtownards, Downpatrick and surrounding. See Areas we cover.
Book a survey
Send us:
- Current oil boiler make and age
- Your grant offer letter (if you have one) OR your NIHE application reference
- Postcode
Related services: Oil to Gas Conversion · Oil Boiler Servicing · Gas Boiler Installation
Related guides: Boiler Replacement Scheme NI · Boiler Grants Northern Ireland · Oil to gas conversion cost NI · Phoenix Natural Gas grants