BoilerFaultCodesHeatline F.22 Fault Code
Also written as F22 — same fault.
The Heatline F.22 fault code means: your boiler has detected that there is not enough water in the system to operate safely and has shut down as a precaution.. It appears on 3 Heatline models in our database.
Technical description: Low water pressure in the heating installation.
DIY fix possible
Locate the filling loop (the flexible silver hose) underneath the boiler.Slowly open the one or two taps on the filling loop until you hear water entering.Monitor the pressure gauge and close the taps once the needle reaches between 1.0 and 1.5 bar.
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Heatline models that show the F.22 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Heatline F.22 fault code information on this page is sourced and cross-checked against the official Heatline service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026