How long do boilers last — and is it worth repairing or replacing?

A modern condensing boiler should last 12–18 years with annual servicing. What tends to fail along the way is predictable: diverter valves and printed circuit boards often need replacing at 8–12 years, at £250–£500 a time, and heat exchangers — the expensive bit — typically fail first at 10–15 years.

That failure pattern drives the repair-or-replace maths. A single affordable repair on a boiler under 10 years old is almost always worth doing, especially if the boiler is still under warranty. But once a boiler passes 15 years, replacement is usually more economical than ongoing repairs — you are paying repeatedly to keep an inefficient unit alive. A 10-year-old boiler typically runs at 80–85% efficiency versus around 94% for a current model, so an old boiler quietly costs you extra on every gas bill as well.

For context on the replacement side: the average boiler replacement in 2026 is £2,000–£3,500 supplied and fitted, and new boilers usually come with a 7–12 year warranty — see our boiler replacement cost guide for the full breakdown by boiler type and house size.

Can you make a boiler last longer? Largely, yes. An annual service is the single biggest factor — it stops small faults becoming failures and is usually a condition of the manufacturer warranty, so skipping it can void cover on the expensive parts. A magnetic system filter, the correct inhibitor in the system and an occasional power-flush of sludgy radiators all take strain off the pump and heat exchanger. Warning signs the end is near include a boiler that needs frequent topping up or resetting, rising gas bills for the same heat, a yellow rather than crisp blue flame, or repeated fault codes — at that point, put repair money towards a replacement instead.

If you do replace, choose the installer as carefully as the boiler — our guide to choosing a boiler installer explains what to check, or get three free quotes from vetted heating engineers.