Boilers
How long does a boiler last — and when should I replace mine?
3 min read · Last updated · Reviewed for accuracy before publishing
Baxi says a boiler lasts 10 to 15 years if it is serviced annually and looked after properly — some soldier on longer, but parts can get harder to find past that point. The rule of thumb: under 10 years old with a single fault, repair; beyond 10–15 with rising bills, repeat faults or discontinued parts, replacement often wins on total cost. The worst option is the one most people choose: waiting for the fatal breakdown on the coldest week of the year.
The warning signs worth acting on
Repeat call-outs for different faults, yellow or lazy flame behaviour flagged at service, rising gas use for the same warmth, pressure that won't hold, and parts on back-order. Any two of those together is the boiler telling you its plans.
Why efficiency shifts the maths
Approved Document L expects a replacement gas boiler in an existing home to meet 92% (ErP) efficiency. An older boiler may fall well short of that, so we estimate the saving from your own gas bills rather than quote a generic figure — before you count the avoided emergency call-outs.
Planned beats emergency, every time
A planned replacement is a surveyed, fixed-price, one-day job with the right boiler chosen calmly. An emergency replacement is whatever's in stock, fitted at distress speed, in a cold house. Same boiler, very different experience and price.
“Boilers rarely die quietly — repeat call-outs, rising gas use, parts on back-order. Any two of those together is the boiler telling you its plans.”
Get the repair-vs-replace numbers →
Sources
- Baxi — How long does a boiler last? ("10 to 15 years if you have it serviced annually and look after it properly"; accessed 19 Oct 2026)
- Baxi — warranty terms (register within 30 days of installation or commissioning; an annual service in line with the instructions keeps it valid; verified 27 Oct 2026)
- GOV.UK — Approved Document L, volume 1: dwellings (before a new heating appliance is installed the central heating and primary hot water circuits should be thoroughly cleaned and flushed, a chemical inhibitor added, the feed water to combination boilers treated in hard water areas, and the system commissioned to BS 7593 — paragraph 8.8 of the 2021 edition incorporating 2023 amendments, 7.8 of the 2026 edition; a replacement gas boiler in an existing dwelling should meet 92% ErP efficiency, or in exceptional circumstances 78% SEDBUK; accessed 19 Oct 2026)
- GOV.UK — Planning permission: after you apply (most applications are decided within 8 weeks; 13 weeks in England for unusually large or complex applications; verified 27 Oct 2026)
David founded Datum after years on the tools across heating and plumbing. He writes the boiler and cost guides from what actually happens on real installs.