How often should a boiler be serviced?

Why your boiler needs a yearly service

Gas Safe Register advises getting your boiler serviced every year, or in line with the manufacturer's instructions if they say otherwise. The manufacturer's manual for your boiler is the best guide, but for almost every gas boiler in a UK home, the answer is once every 12 months.

A service isn't just a box-ticking exercise. It does three useful jobs:

• Safety: the engineer checks the boiler is burning gas properly and that fumes are leaving through the flue. A badly burning boiler can produce carbon monoxide, which you can't see or smell.
• Efficiency: a clean, well-adjusted boiler uses less gas to heat your home, so it costs less to run.
• Warranty: most manufacturers make an annual service a condition of the warranty. Miss one and a later repair may not be covered, even if the boiler is only a few years old.

Small faults found at a service, like a weak seal or a failing part, are usually cheaper to fix than the breakdown they would have caused in the middle of winter.

What happens during a boiler service?

Every engineer works slightly differently, but a standard gas boiler service normally includes:

• A visual check of the boiler, its pipework and controls for leaks, corrosion or damage.
• Removing the boiler casing to inspect and, where needed, clean internal parts such as the burner and heat exchanger.
• Checking gas pressure and flow, and that the boiler is burning the gas correctly.
• Checking the flue and ventilation are clear and working safely.
• Testing the boiler's controls, safety devices and system pressure.
• Running the heating and hot water to make sure everything works, then giving you a record of what was done.

If the engineer finds a problem, they should explain it and tell you whether it's safe to keep using the boiler. Ask for any repair to be quoted separately before it's done.

How much does a boiler service cost?

As of September 2026, UK price guides put a typical gas boiler service at roughly £80 to £140. Checkatrade gives £80 to £120 for a gas boiler, with an average around £100, and MyBuilder quotes £80 to £140. Combi boilers are often at the lower end of the range.

What you pay usually depends on:

• Where the boiler is and how easy it is to reach, for example in a loft or a tight cupboard.
• Its age and condition. Older or neglected boilers can take longer to clean.
• Whether you book a one-off service or a yearly plan that bundles the service with repair cover.
• Any parts needed. These are normally charged on top of the service price.

When you get a price, ask what's included, whether it covers parts, and whether the engineer will give you a written service record. Keep every record with your boiler paperwork.

Is a boiler service the same as a gas safety check?

Not quite. A boiler service is maintenance: the engineer cleans and adjusts the boiler so it keeps working well. A gas safety check looks at every gas appliance, pipe and flue in the property to make sure they're safe to use, and the engineer records the results.

Homeowners aren't legally required to have either, although both are strongly recommended. Landlords are different: they must have a gas safety check carried out every 12 months, give tenants a copy of the record within 28 days, and keep records for at least two years. Many engineers can do a landlord's gas safety check and a boiler service in the same visit.

When is the best time to book a boiler service?

Late summer and early autumn are ideal. You'll find out about any faults before you rely on the heating every day, and engineers are usually easier to book than in the first cold snap, when breakdown call-outs fill their diaries.

If your boiler is new, book the first service for around its first anniversary, and keep to the same time each year so the warranty history is unbroken.

Signs your boiler needs looking at sooner

Don't wait for the yearly service if you notice any of these:

• Black marks, soot or scorching on or around the boiler.
• A lazy yellow or orange flame instead of a crisp blue one.
• The pressure gauge keeps dropping and you need to top it up often.
• New banging, gurgling or whistling noises.
• Water dripping from the boiler or the pipes underneath it.
• People in the home getting headaches, feeling dizzy or sick, especially when the heating is on.

Safety: If you smell gas or think there's carbon monoxide, turn off the gas at the meter if you can, open windows and doors, get everyone outside into fresh air and call the National Gas Emergency Service on 0800 111 999. Don't use light switches or anything that could spark. If anyone feels unwell, get medical help.

Choosing a Gas Safe registered engineer

Only a Gas Safe registered engineer is allowed to service a gas boiler. Anyone working on gas in your home must be registered, and it's worth checking before any work starts. Ask to see their Gas Safe ID card and check:

• The photo matches the person at your door.
• The business name matches the company you booked.
• The card is in date. Engineers renew their registration every 12 months.
• The back of the card lists the type of gas work they're qualified to do, such as domestic boilers.
• The card has the Gas Safe hologram.

If someone doesn't have a valid card, or won't show you one, don't let them work on your boiler. You can also check an engineer's licence number on the Gas Safe Register website.