Glow-worm Flexicom fault F4

What it means

Flame extinguished unexpectedly during an active heating or hot water demand.

Likely causes

1. Gas tap is closed
2. Gas valve connector is loose, unconnected, faulty, or wires are trapped
3. Ignitor connectors are loose, unconnected, faulty, trapped
4. Faulty ignitor
5. Low gas inlet pressure
6. Incorrect gas valve adjustment
7. Electrode ignition leads loose, unconnected, faulty, trapped
8. Electrode broken, defective, or position incorrect
9. Air inlet blocked, flue inlet blocked, flue duct leaking
10. Earthing connection loose, disconnected
11. Condensate blocked
12. Flue components not correctly assembled, fixed or supported
13. Flue or flue terminal obstructed
14. Faulty seals around appliance burner, internal flue seals, door and case seals
15. Incorrect gas type or supply pressure/rate not checked prior to commissioning
16. Analyser not zeroed/calibrated correctly in fresh air prior to use

Where to start

1. Follow boiler manufacturer's installation instructions, verify gas type and check gas supply pressure/rate prior to commissioning
2. Visually check integrity of whole flue system (especially where flue fitted by others) to confirm components correctly assembled, fixed and supported
3. Check manufacturer's max. flue lengths have not been exceeded and guidance followed (e.g. Gas Safe Technical Bulletin TB008)