F22 Meaning: 

According to the Vaillant Installation and Service book, the F22 fault code means ‘Safety switch-off: low water pressure’

F22 Cause:  

 No or too low water pressure in the boiler, water pressure sensor defective, cable to pump or water pressure sensor loose/not connected/defective.


F22 Fix:  

The usual remedy to this is making sure the system pressure is topped up to around 1.2bar and to observe that this pressure does not fluctuate more than 0.5 bar during operation, otherwise servicing may be required.



Please note, should you end up over pressurising the boiler beyond 2 bar, it would be recommended to reduce the pressure by releasing through a drain off valve within the boiler, drain off valve on the heating system or via a radiator vent (this method will take much longer, however is easiest for homeowners)

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