BoilerFaultCodesWhat the manual says
Manufacturer manualFlow temperature rise in heat exchanger too rapid
What causes this fault?
This fault occurs when the water inside the boiler heats up much faster than the system can carry it away, causing the unit to shut down to prevent damage. The most common reasons are a failing internal pump that isn't pushing the water through, or a build-up of sludge and debris that has restricted the narrow channels within the heat exchanger.
This issue often comes to light during the first cold spell of autumn when the heating is turned back on after being idle all summer, which can cause internal pump components to seize.
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 2966: no call-out fees, no surprise bills.
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