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Witten by Bernard Morgan (Engineer) & Adam Apperley (Marketing). Published: February 22, 2024. Updated: February 22, 2024

Glow Worm F1 Fault – How to Fix

Glow Worm F1 Fault | Boilerhut

Encountering an F1 fault code on your Glow Worm boiler signals a crucial need for troubleshooting. This guide will go through the F1 fault code, allowing you to restore your boiler’s functionality.

Glow Worm Boiler - F1 Fault

The F1 fault code on a Glow Worm boiler indicates an ignition problem. It is often related to gas supply issues, signalling the system to halt as a safety measure. This could stem from faulty spark electrodes, probe or ignition lead issues, blocked flue or condensate pipes, a malfunctioning fan, or direct gas supply problems.

Each issue requires a detailed inspection by a Gas Safe registered engineer.

Troubleshooting Steps and Solutions

  • Electrical Component Check: Using a multimeter, engineers can diagnose and fix or replace faulty spark electrodes, probes, or ignition leads, often costing less than £80 for parts.
  • Flue and Condensate Pipe Inspection: Blockages in these pipes can lead to dangerous gas buildup or water overflow. Clearing blockages or installing protective measures like flue guards can mitigate these issues.
  • Fan Functionality: A faulty fan needs immediate attention, potentially requiring speed adjustments or replacements, with costs varying based on the extent of damage.
  • Gas Supply Assessment: Frozen regulators, stuck valves, or blocked burner jets can impede gas flow. Solutions range from thawing and insulating components to replacing malfunctioning parts.

When to Seek Professional Help

Handling a Glow Worm F1 fault entails expertise beyond DIY. Certified Gas Safe engineers are equipped to address and rectify these issues safely and efficiently.

Considerations for Replacement

Old boilers or persistent issues may require replacement. Newer boilers can lower energy bills and repair costs.


Addressing a Glow Worm F1 fault requires understanding its causes and potential fixes. While some preliminary checks can be homeowner-managed, most solutions need professional intervention. Regular maintenance and timely repairs ensure safety and efficiency, while upgrading to a newer model could offer enhanced benefits and savings.

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