BoilerFaultCodesWhat the manual says
Manufacturer manualHigher flow temperature
What causes this fault?
This fault occurs when the water inside the boiler heats up much faster than the system can carry it away, often due to a blockage or a pump failure. It is essentially a safety mechanism that trips when the unit detects that the heat isn't being circulated properly into your radiators or hot water tank. Common culprits include a seized internal pump or a buildup of debris that has restricted the flow of water through the main heat exchanger.
This issue often surfaces during the first cold spell of autumn when the heating is turned back on after sitting idle all summer, which can cause the pump to stick.
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 C1: no call-out fees, no surprise bills.
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