Flue Inspection and Multiple Appliances: Gas Safety Duties for Landlords

Flues sit at the intersection of two compliance headaches for landlords: they are invisible (running inside walls and up through roof voids), and responsibility for them can be split between the flat landlord and the freeholder. Meanwhile, properties with multiple gas appliances raise questions about how many inspections are needed and whether one engineer can cover everything. Both issues are simpler than they look once you understand how GSIUR 1998 treats them.

What the Annual Check Covers on Flues

Every gas appliance the landlord is responsible for that vents through a flue must have that flue checked as part of the annual gas safety check under Regulation 36. The engineer checks flue draw (is the flue pulling combustion gases up and out), spillage (are gases leaking back into the room), physical integrity (cracks, blockages, disconnections), and the terminal position (the external vent must be clear and correctly sited).

This applies to:

• Open-flue appliances — older boilers and gas fires where combustion air comes from the room and exhaust gases rise through a chimney or flue pipe. These are the highest risk because a blocked or defective flue pushes carbon monoxide directly into the living space.
• Room-sealed (balanced-flue) appliances — modern boilers with a concentric flue terminal through an external wall. The combustion circuit is sealed from the room, but the engineer still checks the flue terminal for obstruction, damage, and correct clearances.
• Fan-assisted flues — the engineer checks that the fan is operating correctly and that the pressure switch or flue-flow device shuts the appliance down if the fan fails.

Each flue must be itemised on the Landlord Gas Safety Record alongside the appliance it serves. A CP12 that lists "boiler — pass" without mentioning the flue is incomplete.

Shared Flues in Leasehold Buildings

In a block of flats, the landlord's Regulation 36 duty covers gas appliances they own and provide, plus installation pipework and any flue they provide that serves a tenant-owned appliance. Responsibility for communal gas risers or shared boiler installations serving multiple flats rests with the freeholder or superior landlord under Regulations 3 and 35; individual landlords should confirm that communal flues serving their appliances receive the required checks.

As a flat landlord, you still need to confirm that any shared flue serving an appliance you provide receives the required safety checks. If the freeholder is not maintaining the communal flue system, your own flat's gas safety check could show a spillage defect caused by a downstream blockage you do not control. Document the freeholder's obligations and chase them in writing if needed. You remain responsible for the appliances you provide, their installation pipework, and flues you provide that serve tenant-owned appliances.

Multiple Appliances on One Record

A property with a gas boiler, a gas hob, and a gas fire does not need three separate inspections or three separate CP12s. One annual visit by a qualified engineer can cover all appliances, and they all go on a single Landlord Gas Safety Record with individual entries.

Each appliance gets its own row: description, location, the tests performed, the safety verdict, and any defects found. A pass on the boiler is independent of the hob. If the engineer finds the gas fire is At Risk while the boiler and hob pass, the defect classification and required remedial action apply only to the fire.

The qualification issue matters here. The engineer must hold valid Gas Safe categories for every appliance type present. If you have both natural gas and LPG appliances, or if you have gas fires alongside a boiler, check that the engineer's ID card lists categories for all of them. An engineer without the gas fire category cannot inspect the gas fire — doing so would invalidate that portion of the record.

Where no single engineer covers all categories, two visits may be needed. Make sure the record or records together identify every appliance and flue checked and the qualified engineer who checked each; provide the required record or records to the tenant within the 28-day window.

For a system that tracks your property's appliance inventory against engineer qualifications and ensures nothing falls off the annual record, the Landlord Gas Safety Certificates guide covers the full process.

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