When is a boiler not worth repairing?

A boiler generally isn't worth repairing once it's over 12–15 years old, has broken down two or more times in the last couple of years, or when a single repair quote comes to more than about half the cost of a new boiler (roughly £1,000–£1,500). At that point you're usually throwing good money after bad, and a new, efficient boiler pays back through lower bills and reliability.

How much does a boiler repair cost in 2026?

The average UK boiler repair is around £300, with most falling between £120 and £750 depending on the fault. A gas valve is roughly £180–£220, a heat exchanger £400–£750. Call-out fees for an independent Gas Safe engineer are typically £60–£100, and emergency or out-of-hours visits cost more.

At what age should you replace a boiler?

Most gas boilers last 10–15 years. Under about 10 years with a minor fault, repair is usually the right call. Once a boiler is past 12–15 years — especially if it's breaking down repeatedly or running inefficiently — replacement generally makes more sense than continuing to fix it.

Is it cheaper to repair or replace a boiler?

A single minor repair (around £300) is far cheaper up front than a new boiler (£1,800–£3,500 installed). But repeated repairs on an old, inefficient boiler add up, and an old boiler wastes money on gas every month. Over a few years, a new efficient boiler often works out cheaper than nursing an old one along.

Boiler Advice

Repair or Replace? When Your Boiler Isn’t Worth Fixing

22 July 2026 • 7 min read

An older boiler that's broken down — deciding whether to repair or replace it

Your boiler’s packed up, an engineer’s given you a repair price, and now you’re wondering whether it’s worth it or whether you’re just delaying the inevitable. Here’s the honest rule of thumb: repair it if it’s under about 10 years old and the fix costs well under half a new boiler; replace it if it’s past 12–15 years or it’s broken down more than once recently. Below is how to make the call properly — the money test, the age question, and the signs you’re throwing good money after bad — with real 2026 figures.

The Two-Minute Money Test

Before anything else, do this simple sum. A new combi boiler costs £1,800–£3,500 installed in 2026 (see our full boiler cost guide). Compare your repair quote to that:

Repair quote under ~25% of a new boiler (roughly £600 or less): almost always repair.
Repair quote over ~50% of a new boiler (roughly £1,000–£1,500+): replacement usually wins — especially on an older boiler.
In between: it’s a judgement call, and age plus repair history decides it (below).

The short version of the rule: if a single repair is more than about half the price of a new boiler, replace it. You’d be putting a big chunk of a new boiler’s cost into an old one that could fail again next winter.

What Repairs Actually Cost

To run that test you need a feel for what’s a fair repair price. In 2026 the average boiler repair is around £300, with most falling between £120 and £750:

Common repair	Typical cost
Thermostat / valve fix	£100 – £300
Gas valve replacement	£180 – £220
Kettling / limescale repair	~£300
Heat exchanger replacement	£400 – £750

Call-out fees for an independent Gas Safe engineer are usually £60–£100; emergency or out-of-hours visits (evenings, weekends, bank holidays) cost noticeably more. The big, expensive parts — heat exchanger, gas valve — are the ones that tip an older boiler into “replace” territory.

The Five Things That Decide It

Age. Most boilers last 10–15 years. Under 10 with a one-off fault — repair. Past 12–15 — lean towards replacing, because more failures are coming.
The repair cost vs a new boiler — the money test above. Over ~half, replace.
Repair history. Two or more breakdowns in two years usually means the components are wearing out together — the next failure is likely to be a big one. If you’ve spent £800–£1,000 on repairs in three years and it’s over 8 years old, you’re in diminishing returns.
Efficiency. An old boiler can run at 70% efficiency or worse; a new A-rated one is 90%+. On an old, tired boiler you’re quietly overpaying on gas every month — a new one claws some of that back.
Parts availability. Very old or discontinued boilers can have scarce, pricey parts — sometimes the deciding factor, because the repair simply isn’t possible or economic.

Repair If… / Replace If…

Repair if…

It’s under ~10 years old · this is the first or only fault · the repair is well under half a new boiler · and parts are readily available. A young boiler with a single failed part is almost always worth fixing.

Replace if…

It’s past 12–15 years · it’s broken down more than once recently · the repair is more than about half a new boiler · parts are obsolete · or it’s clearly running inefficiently and your gas bills show it.

Put simply: repair the young, replace the old. A £300 fix on a 7-year-old boiler is a no-brainer; a £900 fix on a 14-year-old one that’s failed twice already is money you’ll likely spend again.

Don’t Be Pushed Into a New One

Worth saying plainly: not every engineer who recommends a full replacement is right, and a new boiler is a much bigger sale than a repair. If your boiler’s relatively young and you’re told it needs replacing, get a second opinion — especially before committing to a four-figure job. A straight-talking Gas Safe engineer will tell you honestly whether yours is worth saving, and won’t push a new boiler you don’t need. Equally, if it’s genuinely old and unreliable, they’ll save you from pouring more money into it.

The Short Version

Do the money test first: if a repair is more than about half the cost of a new boiler (~£1,000–£1,500), or the boiler is past 12–15 years or breaking down repeatedly, replacing usually makes more sense. Under ~10 years with a single, affordable fault, repair every time. Average repairs run around £300; a new combi is £1,800–£3,500 installed. When in doubt, get an honest second opinion before spending four figures either way.