Boilers
What should a proper boiler service include?
3 min read · Last updated · Reviewed for accuracy before publishing
A proper annual service is done by a Gas Safe registered engineer, who checks the boiler's main components for wear and checks for carbon monoxide, as Baxi describes. The Gas Safety (Installation and Use) Regulations also require the flue, the supply of combustion air, operating pressure or heat input and safe operation to be examined. Baxi says a service takes 40 to 60 minutes on average. A five-minute look and a sticker is not a service, whatever the invoice says.
Why it matters beyond safety
Baxi says all its warranties require a yearly service, and other manufacturers set their own conditions, so check yours. Skip a year and a long warranty can lapse — the expensive way to save a little. By law the engineer must be Gas Safe registered.
Baxi's 800 Combi 2, for example, is covered for 10 years, subject to registration within 30 days and an annual service.
What we leave you with
A completed checklist — what was measured, what the readings were, anything flagged for attention and how urgent it honestly is. 'Watch this next year' and 'fix this now' are different things, and we say which. A dated copy stays with you for your warranty file.
The best time to book
Before the heating season, when small problems are cheap to fix and you aren't waiting for a breakdown slot in the cold. Landlords: pair it with the CP12 in one visit.
“A real service produces readings, not just a sticker. If nobody showed you numbers, nobody measured anything.”
Sources
- Baxi — How long does a boiler service take? ("between 40 and 60 minutes" on average; Gas Safe engineers check for CO at every service and check the main components for wear; "all our warranties have a requirement that the boiler has a yearly service"; accessed 19 Oct 2026)
- Gas Safety (Installation and Use) Regulations 1998, regulation 26(9) (after work on a gas appliance the engineer must examine the effectiveness of any flue, the supply of combustion air, its operating pressure or heat input (or combustion performance where that is not reasonably practicable) and its safe operation; accessed 19 Oct 2026)
- HSE — Gas safety: home owners and occupiers ("Anyone employed to work on gas appliances in domestic premises must be a Gas Safe registered engineer"; the engineer's competencies are marked on the back of their Gas Safe ID card; accessed 19 Oct 2026)
- Baxi — warranty terms (register within 30 days of installation or commissioning; an annual service in line with the instructions keeps it valid; verified 27 Oct 2026)
David founded Datum after years on the tools across heating and plumbing. He writes the boiler and cost guides from what actually happens on real installs.