Error 2927 B

Safety first:

1) If you smell gas: do not operate electrical switches or the boiler. Open windows, leave the building immediately and call your local gas emergency number (or 999 in the UK if you believe there is an immediate danger). Do not attempt to fix the boiler.

2) Ensure you have a working carbon monoxide alarm fitted near the boiler and on every floor; if it alarms, evacuate and call emergency services and a Gas Safe engineer.

3) If there is no smell of gas and no immediate danger, isolate the boiler from its electrical supply before doing any intrusive checks and follow the rest of these checks carefully.

Initial homeowner checks you can safely do:

1) Attempt a single reset using the boiler's reset/control button. Wait and watch a full ignition cycle; note whether the code returns immediately or after several attempts. Do not repeatedly reset if the code returns.

2) Check other gas appliances (hob, gas fire) to confirm the house gas supply is present and the gas meter/main appliance isolation valve is open. If other appliances don’t light, contact your gas supplier.

3) Check the boiler display and note the exact error code (2927 B) and any accompanying symbols or sequence of flashes. Take a photo or write down timings to give to the engineer.

4) Inspect the flue terminal outside for obvious blockages (birds’ nests, leaves, ice) and ensure any required air vents or combustion air openings are not blocked. If you see a removable blockage you can safely clear it from outside but do not dismantle the flue.

5) Check boiler water pressure and basic operating conditions (pressure roughly 1–1.5 bar when cold). Low pressure is not the primary cause of flame failure but is good to confirm.

Further diagnostic checks (what an engineer will do; homeowners should avoid attempting unless competent and qualified):

1) The ignition/ionisation electrode and lead: engineers will check that the electrode is clean, correctly positioned, and that the ignition lead and connector are dry and secure. Homeowners may visually inspect for obvious damage or heavy soot but should not dismantle burner components.

2) Gas supply at the appliance: an engineer will check gas inlet pressure and the internal gas valve operation. Do not attempt to adjust or test the gas valve yourself.

3) Flue and fan operation: the engineer will test the fan for correct speed and check flue gas sensing and flue thermostat for faults or blockages, and clean the flue gas-side of the combustion chamber if required.

4) Burner settings and minimum load: the engineer will check burner calibration, minimum firing settings and the burner control unit. Incorrect settings or a mis-set burner can cause flame loss at low modulation.

5) Control electronics: if flame sensing and gas supply are OK but problem persists, the burner control unit or main PCB may be faulty and require replacement by a qualified engineer.

When to call a professional and what to tell them:

1) Call a Gas Safe registered engineer if the error returns after a single reset, if you find no obvious external blockage, if the electrode appears damaged or wet, or if other gas appliances fail. Also call immediately if you smell gas or if a CO alarm has sounded.

2) When you contact the engineer provide: the exact error code (2927 B), whether you smelled gas, whether other gas appliances work, what you checked (flue terminal, vents, reset), and whether the fault is intermittent or persistent. Send photos of the display and the flue terminal if you can.

Final notes and precautions:

1) Do not repeatedly reset the boiler; one attempt is OK to clear a transient fault but repeated resets can be dangerous and will delay a proper diagnosis.

2) Do not attempt gas-side repairs, replace gas valves, or perform electrical or burner adjustments yourself unless you are Gas Safe qualified. Those tasks must be done by a Gas Safe registered engineer.

3) If the problem is intermittent, arrange a service test and full combustion check. If persistent, do not use the boiler until a qualified engineer has confirmed it is safe to operate.