BoilerFaultCodesTechnical description
Variation on temperature of primary and/or return too high
What causes this fault?
This fault occurs when the boiler's internal sensors detect that heated water isn't moving away from the heat exchanger quickly enough. The most common reasons are a mechanical failure of the circulation pump, a build-up of sludge blocking the pipes, or a faulty sensor providing incorrect temperature readings. To prevent the unit from overheating, the system shuts down as a safety precaution.
This issue often surfaces when the heating is first turned on after summer, as the pump can seize up after long 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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