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When should you replace your boiler?

Replace your boiler when it is old, breaks down often, or costs nearly as much to mend as to replace. Most boilers are built to last roughly ten to twelve years. This guide lists seven signs, so you can decide calmly before it fails in winter.

Only a Gas Safe registered engineer may work on a gas boiler. We do not vet or guarantee the engineers who respond to our quote form, so check the Gas Safe Register yourself.

Seven signs it is time

1. It is over ten to twelve years old

Many manufacturers expect a boiler to last about ten to twelve years with regular servicing. After that, parts get harder to find and breakdowns become more likely. Age alone is not a reason to replace it, but it still raises the odds.

2. It breaks down more than once a year

One fault is normal wear. Repeated call-outs for different faults suggest the boiler is failing. The repair bills add up, yet they buy you no extra life.

3. A repair costs close to a new boiler

If a quote for repair is a large share of a new, fitted boiler, replacement is usually better value, because a new boiler comes with a warranty and modern efficiency. Ask the engineer for both prices in writing.

4. Your bills are rising

If you use heating the same way but your gas bills climb, an old boiler may be wasting fuel. Although savings differ, older non-condensing boilers are less efficient than modern condensing ones. Savings differ between homes, so ask for an estimate for yours.

5. It makes odd noises or smells

Banging, whistling or kettling can point to a failing part or limescale, since water and heat build up pressure. A smell of gas or any sign of carbon monoxide is an emergency. Leave the house and call the National Gas Emergency Service on 0800 111 999.

6. Parts are hard to get

For very old models, an engineer may struggle to find parts, because makers stop supplying them. That can turn a small repair into a long wait without heat.

7. The flame or system looks wrong

A yellow or orange flame instead of a steady blue one, or black marks around the boiler, needs an engineer at once. Do not use the boiler until an engineer checks it.

What a new boiler costs

Price guides from MyJobQuote and Fantastic Services suggest a like-for-like combi swap costs about £1,800 to £3,000 fitted, although some guides go higher. See our new boiler cost guide for the detail and the sources.

Grants rarely cover a like-for-like gas boiler, because the main schemes fund heat pumps. Our boiler grants guide explains what each scheme does fund.

How to get a fair price

Get at least three written quotes, and compare what each includes, because the cheapest may leave things out. Ask about the boiler make and warranty, the flue, controls and removal of the old unit. Then choose on value, not on price alone. If your boiler has failed, see emergency boiler repair.

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Compare quotes from plumbers in your city.

Keep reading and compare quotes

Each city page covers prices, how to choose and how to get free quotes in that area. You can also start from our plumbers page.

Before you choose an engineer, read how to find a tradesman you can trust and how to read tradesperson reviews.

Frequently asked questions

How long does a boiler last?

Most last around ten to twelve years with regular servicing. Some last longer, while some fail sooner.

Is it worth repairing an old boiler?

Sometimes. If the repair is small and the boiler is otherwise sound, repair is fine. If the boiler is old and the repair is large, replacement is often better.

Should I service my boiler every year?

Manufacturers usually advise an annual service, and it may be a condition of the warranty. A service also helps catch problems early.

Will a new boiler cut my bills?

A modern condensing boiler is more efficient than an old one, so many homes save fuel. The saving depends on your home and how you use heating.

Written by the Trusted Tradesmen Quotes team. Last updated 9 October 2026.