Sime Short Cycling / Early Flame Loss

Boiler starts then shuts down after a few seconds without showing an error code

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Blocked or undersized system, Incorrect minimum power setting, Faulty flame detection, Over-sensitive temperature sensor

Safety first: Monitor the boiler; if it repeatedly starts and stops, avoid prolonged operation until checked.

Check all radiators are open: Ensure TRVs and valves are open to provide sufficient load.
Lower flow temperature: Reducing CH flow temperature can lengthen run times and reduce cycling.
Engineer tasks: The engineer should check flame stability, sensor readings, and adjust minimum burner power within Sime's commissioning parameters. They should also verify system design and bypass arrangements.

Hard 4/5

Burner Assembly

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