Boiler service: how often, what it costs and when to book

How often does a boiler need a service?

Once a year. The Health and Safety Executive (HSE) says gas appliances, flues and pipework should be serviced at least annually by a Gas Safe registered engineer. Which? and the Energy Saving Trust give the same advice.

If you own your home, there’s no law that makes you do it. There are still good reasons to:

• Safety. A service checks the flue, the seals and the safety devices, which is how problems like a carbon monoxide leak get caught.
• Your warranty. If the boiler is still under its manufacturer’s warranty, missing a yearly service could invalidate it. Check the terms in your paperwork.
• Fewer breakdowns. An engineer can spot a worn part before it fails on the coldest night of the year.

If you rent

Your landlord must arrange a gas safety check every 12 months, carried out by a Gas Safe registered engineer, and you can’t be charged for it. According to Shelter, they must give you a copy of the record before you move in and within 28 days of each yearly check. They can book the visit up to two months early without changing the date the next one is due.

What does a service cost?

Prices vary by area, by the time of year and by the boiler. As checked on 31 October 2026:

• Which? says a one-off gas boiler service should cost somewhere from £70 to £110, with an average of around £79.
• The Energy Saving Trust, in November 2025, quoted around £80 to £120.

Any repairs or parts the engineer finds are extra. Some people pay monthly for a boiler cover plan that includes the service. Whether that’s worth it depends on what the plan covers and how old your boiler is, so compare the yearly total with a one-off service.

What’s checked

A proper service isn’t a quick look. Which? lists a visual check of the boiler and flame, flue checks, pressure or heat input checks, safety device checks, checking the case seal, taking off the casing to inspect the main parts, firing the boiler to look for faults, cleaning where needed, and a written report. It says a good service should take at least 30 minutes. The Energy Saving Trust says around 40 minutes to an hour.

Keep the report. It’s your proof of servicing if you ever need to claim on the warranty.

Why winter is the worst time to book

When the heating goes on, breakdowns go up and engineers get booked out with urgent call-outs. That can mean a longer wait for a routine service, and emergency repairs in winter can cost more. Booking in spring or summer means the boiler is checked before you need it, while there’s still time to fix anything it finds.

If it’s already autumn and you’re overdue, book now rather than waiting another year. Then set next year’s date earlier.

Check the engineer

Only a Gas Safe registered engineer can legally work on a gas boiler. Ask to see their Gas Safe ID card: the back shows which types of gas work they’re qualified for. You can check an engineer on the Gas Safe Register website or by calling 0800 408 5500.

HSE also recommends a carbon monoxide alarm as an extra precaution, but says it doesn’t replace a yearly service.

A simple plan

1. Find your last service date. It should be on the last report or in the boiler’s logbook.
2. Pick a month outside winter for next time, ideally between April and September.
3. Book a Gas Safe registered engineer and check their ID card when they arrive.
4. Keep the report with your warranty paperwork.
5. Set a reminder for the same month next year.

While you’re looking at heating costs, check when your energy fix ends. And if you have a boiler cover plan, it renews every year too, so it’s worth a look at the renewal tax before it rolls over.