BoilerFaultCodesTechnical description
Temperature difference between flow/return NTC too large
What causes this fault?
This fault occurs when the water inside the boiler heats up too quickly because it isn't moving away into your radiators fast enough. The most common reasons are a failed internal pump that has stopped spinning or a blockage in the pipework that is restricting the flow of water. Either way, the boiler shuts down as a safety precaution to prevent the heat exchanger from overheating.
This fault is more common in autumn when heating systems are turned back on after a long summer break, as pumps can seize during periods of inactivity.
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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