How often should you service your boiler?

The short answer: once a year

A domestic gas boiler should be serviced every twelve months by a Gas Safe registered engineer. Manufacturers set the interval, gas safety guidance is built around it, and almost every boiler warranty makes annual servicing a condition of cover.

Skipping a year rarely causes an immediate problem, which is exactly why it happens. The cost shows up later, as a component that failed earlier than it should have, or a warranty claim that gets refused.

What actually happens during a service

A proper service is not a five-minute look at the display. The engineer inspects the appliance, flue and ventilation, analyses the flue gases to confirm the boiler is burning correctly, checks the gas rate against the manufacturer's data, cleans the components the manufacturer specifies, and verifies system pressure, expansion vessel charge and controls operation.

You should be left with a written record of what was checked and what was found — including anything worth watching before next year.

Why the timing matters

Book the service in late summer or early autumn if you can. Heating engineers everywhere are busiest during the first cold snap, and a fault found in September is a scheduled repair rather than an emergency in December.

If you have just moved into a property with no service history, get the appliance checked regardless of when the last one was — you have no way of knowing what was done.

Landlords: servicing is not the same as a CP12

A landlord gas safety check confirms an appliance is safe. A service cleans and maintains it. They are separate pieces of work with different purposes, and only the safety check is a legal duty each year. Most landlords sensibly book both on the same visit so the property is safe and the appliance keeps working.