Boiler shows E1 234, may indicate flue gas recirculation or combustion issues.

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

Incorrect flue terminal position, Damaged flue seals, Blocked flue, Condensate backing up into flue

Safety first: Flue and combustion work must be done by a Gas Safe engineer. Do not modify the flue yourself.

Engineer checks:

Inspect the entire flue system for correct assembly, secure joints, and intact seals.
Verify terminal clearances and orientation comply with Worcester Bosch installation instructions.
Check for signs of condensate leakage or pooling in the flue; ensure condensate trap and pipework are clear.
Perform a combustion analysis and rectify any issues with gas/air ratio.

Professional Required 5/5

Flue Kit and Seals

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