Boilers
Should I repair or replace my boiler?
3 min read · Last updated · Reviewed for accuracy before publishing
The rule of thumb: under about 10 years old with a single, non-major fault — repair. Beyond the 10–15-year mark, or facing a big-ticket part (heat exchanger, PCB, fan) on top of rising bills and repeat call-outs — replacement often wins on total cost. The two questions that settle most cases: is the failed part a major one, and are parts still available for your model? A discontinued boiler needing a heat exchanger is a replace; a five-year-old boiler needing a diverter valve is a repair. We quote both, every time, and let you choose with the real numbers.
When repair is the right call
A relatively young boiler (say, under 10) with a well-defined, cheaper fault — a valve, a sensor, a pump — is worth repairing. It's sound, parts are available, and a new boiler wouldn't pay for itself. Replacing it would be selling you something you don't need, which we won't do.
When replacement wins
Age beyond 10–15 years, a major component failure, discontinued parts, falling efficiency and repeat breakdowns for different faults — any two of those together and the maths tips. A new boiler comes with a fresh warranty and, under Approved Document L, must meet 92% (ErP) efficiency in an existing home — before you count the avoided emergency call-outs.
The honest number we give you
We diagnose the actual fault, then quote the repair and a like-for-like replacement side by side — including the efficiency difference and the warranty you'd gain. No pressure, no scare tactics; the decision is yours, made on real figures rather than a doorstep sales pitch.
“Two questions settle it: is the failed part a major one, and can you still get parts? We quote both routes every time — the decision should be yours, made on real numbers.”
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)
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.