Most modern domestic boilers last somewhere between ten and fifteen years. Serviced annually and installed properly, the top end of that is realistic. Neglected, or installed on a system full of sludge, ten is optimistic.

What actually shortens a boiler life

• Sludge and scale. The single biggest factor. A system that has never been flushed or dosed with inhibitor wears the heat exchanger and kills pumps.
• Skipped servicing. Small faults become large ones, and it invalidates most warranties.
• Being oversized. A boiler far larger than the house needs cycles on and off constantly, and cycling is wear.
• Hard water. Scale on the heat exchanger, which matters across Cambridgeshire and north Hertfordshire.

The honest repair-or-replace test

There is no single rule, but this is the arithmetic we would use on our own house.

• Under 8 years. Repair. It should not be failing and parts are readily available.
• 8 to 12 years. Repair, unless the failure is a heat exchanger or a gas valve and the boiler has a history.
• Over 12 years, with a second significant repair inside two years. Replacement is usually cheaper across three years than continuing.
• Parts no longer available. Decision made for you.

Signs it is nearing the end

• Repairs more than once a year
• Rising gas bills with no change in use
• Persistent kettling that returns after flushing
• Parts becoming hard to source
• A non-condensing boiler, which is inherently far less efficient than anything current

What makes the replacement last

Correct sizing for the property rather than the biggest available, a system cleanse before the new boiler goes on, a magnetic filter, the right inhibitor dose, and an annual service. A new boiler fitted onto a dirty system inherits the problem that killed the last one.

Frequently asked questions

How long should a combi boiler last?

Ten to fifteen years with annual servicing.

Is it worth repairing a 15 year old boiler?

Usually not if it needs a major component. Get the figures before deciding.

Does a new boiler need a power flush first?

A system cleanse, yes. Fitting a new boiler to a sludged system shortens its life and can affect the warranty.

Do boilers get less efficient with age?

Yes, and an old non-condensing boiler is markedly less efficient than a current one.

Want it sorted properly?

Still stuck? We repair this fault regularly across Hertfordshire, Bedfordshire and Cambridgeshire. Call 01462 506374 to get an engineer booked, or to talk it through first if you would rather. Genuine 24 hour cover, 365 days a year.

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