F22
Safety cutout due to low water
System pressure too low — refill to 1.0–1.5 bar and check for leaks.
Fault code index
Glow-worm Boiler Fault Codes Explained
Every common Glow-worm lockout code, what it actually means, and whether it is a simple pressure top-up or a safety fault needing a Gas Safe registered engineer.
Glow-worm diagnostic code matrix
F24
Pump fault / rapid temperature rise
Poor circulation from a failed pump, closed valve or sludge blockage.
F1
Flame loss after ignition
Gas supply or electrode fault requiring engineer attendance.
F28
Ignition failure at start-up
Gas valve, ignition leads or PCB fault.
F75
Pressure sensor / pump fault
No pressure change detected on pump start — sensor or pump replacement.
F13
Contact protection fault
Wiring or PCB communication issue on Energy and Ultimate ranges.
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Glow-worm fault codes — FAQs
What does F22 mean on a Glow-worm boiler?
- F22 indicates safety cutout due to low water. It should be diagnosed by a Gas Safe registered engineer if it returns after a single reset.
Can I clear a Glow-worm fault code myself?
- Low pressure codes can usually be cleared by repressurising the system. Ignition, fan, flame and overheat codes need an engineer.
Do you carry Glow-worm parts?
- We stock common Glow-worm fans, pumps, sensors and electrodes, so many repairs are completed on the first visit.
Will a repair affect my Glow-worm warranty?
- No. We fit genuine manufacturer-approved parts and record the work, keeping your warranty intact.
How fast can you attend a Glow-worm breakdown in Warrington?
- Same-day or next-morning in most cases — we cover Warrington and the surrounding areas every day.
Glow-worm boiler locked out? We can help today.
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