BoilerFaultCodesTechnical description
ALTERNATING 'H' 'F' GO TO FRAME 94
What causes this fault?
This fault occurs when the boiler fails to detect a flame after multiple ignition attempts, leading to a safety shutdown. The most common reasons include a lack of gas supply to the unit, a worn-out ignition spark electrode, or a blockage in the flue that prevents the necessary air-to-gas ratio for combustion.
This fault is frequently reported during extreme cold snaps, as the external condensate pipe can freeze and back up, preventing the boiler from successfully igniting.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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