Boiler shows F16, burner may light then shut down, combustion unstable

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 electrode gap or position, Contaminated burner, Poor earth bonding, Low gas pressure at burner

Safety: Isolate power and gas before internal combustion checks. Only a qualified engineer should open the combustion chamber.

Check earthing: Ensure the boiler's earth connection is secure at the fused spur and consumer unit.
Engineer tasks:
- Inspect and clean the burner and ionisation electrode.
- Set the correct electrode gap and position as per Glow-worm manual.
- Measure gas pressure and adjust if necessary.
- Check for correct flue installation and adequate air supply.

Weak flame signal issues must be resolved to prevent unsafe operation.

Professional Required 5/5

Ignition and Ionisation Electrode Set

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