BoilerFaultCodesWhat the manual says
Manufacturer manualCondensate pump or feedback of accessories blocks heating | Condensate pump defective or flume flap feedback triggered
What causes this fault?
This fault occurs when the boiler detects a blockage or failure in the system that removes waste gases and water. It is usually caused by a stuck internal flap that prevents exhaust fumes from escaping safely, or a pump failure that stops waste water from being drained away. When these systems fail, the boiler shuts down as a safety precaution to prevent internal flooding or the buildup of dangerous gases.
This fault can be more frequent during extreme cold spells if the external pipe that carries waste water away freezes and causes a backup into the pump area.
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.
Avoid the next call-out bill
A cover plan would handle faults like F.77: no call-out fees, no surprise bills.
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