BoilerFaultCodesYour boiler has stopped working because it cannot properly drain away waste water or there is a blockage in the ventilation system.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Fault: Flue non-ret. valve/condens. pump - No flue non-return flap feedback; condensate pump overflow
What causes this fault?
This fault happens when waste water from the combustion process cannot escape because the condensate pump has failed or the drainage pipes are blocked. It can also be triggered if the safety flap in the exhaust flue is stuck, which prevents the boiler from safely venting gases. When the system detects that water is backing up or air cannot flow correctly, it shuts down to prevent internal flooding or safety issues.
This fault is more common during freezing winter temperatures, as the external pipe that carries waste water away can freeze solid and cause a backup into the pump.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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