Boiler repair vs replacement — which is cheaper?
When to repair a UK boiler and when to replace it — typical 2026 prices, lifespan, energy savings, and the rules around installer choice.
Updated 14 May 2026
If your boiler breaks down and you're staring at a £400 repair quote, the question is always the same: fix it or replace it? Here's the rule of thumb most heating engineers use.
The 50% rule
If the repair quote is more than 50% of a like-for-like replacement, and the boiler is more than 7–8 years old, replace. Modern combi boilers run much more efficiently — a typical replacement saves £200–£400 a year on a 4-bed home.
Typical repair costs
Diverter valve: £180–£280. PCB (electronic board): £250–£500. Heat exchanger: £350–£700 (often the moment to replace). Pressure release valve: £100–£180. Diagnostic call-out: £60–£90.
Typical replacement costs
A standard combi like a Worcester Bosch 2000 or Ideal Logic Max installed: £1,800–£2,500. A premium combi (Vaillant, Viessmann): £2,500–£3,500. System or regular boiler with cylinder: £2,800–£4,500. Add £400–£1,000 if you're moving the boiler location or upgrading the gas supply.
Lifespan
Modern condensing boilers last 10–15 years with annual servicing. Beyond 15 years, parts get harder to source and efficiency drops 10–20% below modern equivalents.
Manufacturer warranty matters
Worcester, Vaillant and Viessmann offer 10–12 year warranties when installed by an accredited installer. That's effectively £150–£300/year of free cover.
Frequently asked questions
Is it worth getting boiler cover?▾
If your boiler is under 7 years old, probably not — repairs in that period are rare. If it's 8–12 years old and out of warranty, cover (£15–£25/month) often pays for itself.
Can I install a boiler myself?▾
Absolutely not. Any work on a gas boiler in the UK must be done by a Gas Safe registered engineer. DIY installation is illegal and invalidates all home insurance.