BoilerFaultCodesGlow-worm F22 Fault Code
The Glow-worm F22 fault code means: your boiler has detected that there is not enough water pressure in the system to operate safely, which has caused it to shut down.. It appears on 23 Glow-worm models in our database.
Technical description: Low water pressure or No water in boiler
What causes the Glow-worm F22 fault?
This fault occurs when the water pressure inside your heating system drops below the minimum level required for the boiler to heat up safely. The most common reason is a slow leak from a radiator valve or pipework, though it can also happen if you have recently bled your radiators and didn't top the pressure back up.
This fault often appears when you turn your heating back on for the first time in autumn, as small leaks or air pockets may have developed during the months of inactivity.
DIY fix possible
Locate the external filling loop, which is usually a flexible silver hose with two small valves underneath or near the boiler.Slowly open both valves to allow water into the system while watching the pressure gauge.Close both valves tightly once the pressure gauge reaches between 1.0 and 1.5 bar.
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Glow-worm models that show the F22 fault code
Click a model for the full fault code list and model-specific repair notes.
- Betacom4 Repair: £80-150
- Easicom 24 Repair: £0-120
- Easicom3 Combi Repair: £0-£120
- Easicom3 System Repair: £80-120
- Energy System Repair: £0-£100
- Energy7 Combi Repair: £80-150
- Energy7 System Repair: £80-150
- Essential Repair: £80-150
- Flexicom 18sx Repair: £60-120
- Flexicom 24c / 28c Repair: £80-150
- Flexicom cx Repair: £80-150
- Flexicom hx Repair: £60-120
- Flexicom hxi Repair: £80-150
- Flexicom sx Repair: £60-120
- Sustain 12s Repair: £0-120
- Ultimate 3 25R Repair: £0-£120
- Ultimate3 Combi Repair: £80-150
- Ultimate3 System Repair: £0-£120
- Ultracom 2 CXI Repair: £60-120
- Ultracom 2 HXI Repair: £60-120
- Ultracom 24cx 30cx Repair: £60-120
- Ultracom 35 Store Repair: £60-120
- Ultracom cxi Repair: £60-120
Source
Glow-worm F22 fault code information on this page is sourced and cross-checked against the official Glow-worm service / installation manuals for each affected model.
- Glow-worm Betacom4 manual (PDF)
- Glow-worm Easicom 24 manual (PDF)
- Glow-worm Easicom3 Combi manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026