Annual boiler service: what should happen at the visit

The HSE advises that gas appliances, flues and pipework are serviced at least once a year by a Gas Safe registered engineer unless the manufacturer says otherwise. On a gas boiler, the engineer checks the gas pressure and burner, measures combustion with a flue gas analyser, inspects the flue along its accessible length and its terminal outside, checks seals, the condensate trap and pipe, the heat exchanger, the expansion vessel and system pressure, and tests the safety devices.

The visit should end with a written record: what was checked, the combustion readings and any defects found. Many manufacturers' extended warranties depend on annual servicing, so keep those records together with the Benchmark checklist from installation.

Some engineers offer a cheaper 'safety check' in place of a service. It may confirm the boiler is safe to use, but it is not the same as the manufacturer's service routine. Ask which one you are booking.

• combustion analysis readings
• visual and operational check of the flue and terminal
• condensate trap cleaned, pipe checked for frost risk
• system pressure and expansion vessel charge
• safety devices and controls tested
• written record and any warning notice explained

Landlords must have every gas appliance and flue they provide checked every 12 months and give tenants the record. That legal check confirms the appliance is safe; it does not require the full manufacturer's service, although many engineers do both at one visit. If you are a landlord, book both explicitly so you do not end up with one and assume it was the other.

Homeowners have no legal duty to service their own boiler, but the HSE's advice, the warranty terms and basic safety all point to doing it yearly.

Source: hse.gov.uk

LPG boilers are gas appliances and need a Gas Safe engineer with LPG on their card. Oil boilers are serviced by technicians registered with OFTEC or another competent person scheme for oil; the service includes the burner nozzle and filter, combustion analysis and a check of the oil tank and supply line.

Biomass and pellet boilers need more frequent attention: ash removal, cleaning of the heat exchanger and flue, and an annual service by a technician trained on that make. The chimney or flue of any solid fuel appliance needs sweeping, and the MCS handover pack sets out the servicing schedule.

The HSE lists signs of incomplete combustion that can mean carbon monoxide: yellow or orange flames where they should be blue, soot or yellow-brown staining on or around the appliance, a pilot light that keeps going out, and more condensation on the inside of windows than usual. Headaches, dizziness, nausea and tiredness that improve when you leave the house are symptoms to take seriously.

If you suspect a gas leak or carbon monoxide, call the National Gas Emergency Service on 0800 111 999, stop using the appliance, ventilate the room and seek medical advice. Do not wait for the next service.

Tell us the boiler type, make and fuel, and whether it is a home or a rented property. Engineers in your area see the job without your personal details, and one engineer can buy it; nobody else can then see it. The engineer pays Offrano, not you.

We send you the engineer's name, address and phone number before your details go to them. We cannot promise that every request is taken, and unsold requests are withdrawn after 21 days. Offrano confirms that the buyer is a registered business, not its Gas Safe or OFTEC status, so check that yourself before the visit.