Cost of Boiler Installation in the UK (2025)
Boiler installation costs £500–£1,200 in labour. The total cost (boiler + installation) typically ranges from £1,800 to £4,500 depending on boiler brand and type.
Like-for-like vs conversion
A like-for-like swap (e.g., replacing an old combi with a new combi in the same location) is the most straightforward and affordable installation. Converting from a conventional (heat-only) system with a cylinder to a combi boiler requires removing the cylinder and cold water tank, which adds £200–£600 to the job. Your heating engineer will advise on the best approach.
Boiler brands and warranties
Worcester Bosch, Viessmann, and Vaillant are consistently rated as the most reliable brands with 10-year warranty options. Budget brands (Ideal, Baxi, Glow-worm) cost less upfront but may have shorter warranties. An engineer who is brand-accredited can offer the manufacturer's extended warranty, which is worth having.
Cost Breakdown
All prices are indicative UK averages for 2025. Actual costs vary by location, specification, and contractor. London and South East rates are typically 20–35% higher.
| Item | Low | High |
|---|---|---|
| Labour only (like-for-like swap) | £500 | £1,000 |
| Budget combi boiler + fit | £1,800 | £2,500 |
| Mid-range combi + fit | £2,200 | £3,200 |
| Premium combi + fit | £2,800 | £4,500 |
| System boiler + fit | £2,500 | £4,000 |
| Flue extension or relocation | £150 | £500 |
What Affects the Cost?
- ✓Whether it is a like-for-like swap or system conversion
- ✓Boiler brand and model chosen
- ✓Length of warranty required
- ✓Whether a magnetic filter is included (highly recommended)
- ✓Whether the system needs power flushing before the new boiler is fitted
- ✓Location — London and South East rates are higher
Get Free Quotes for This Work
Post your job on Quote2 and receive up to 3 quotes from local, reviewed tradespeople. Free for homeowners.
Post a Job — It's FreeFrequently Asked Questions
Does my heating engineer have to be Gas Safe registered?
Yes — by law, all work on gas appliances must be done by a Gas Safe registered engineer. Always check their registration at GasSafe.co.uk before booking.
Should I power flush before a new boiler?
If your system has significant sludge build-up (shown by cold radiator spots or discoloured water from the bleed valve), a power flush before installation protects the new boiler and is often required to keep the warranty valid.
How long does boiler installation take?
A straightforward like-for-like swap takes 4–8 hours. A full system conversion can take 1–2 days.