BoilerFaultCodesHeatline F77 Fault Code
The Heatline F77 fault code means: your boiler has detected an issue with the valve that controls the supply of gas to the burner, meaning it has safely shut itself down and will not provide heating or hot water.. It appears on 8 Heatline models in our database.
Technical description: Fault in gas valve motor. (Defective gas valve / Defective condensate pump (option))
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Heatline models that show the F77 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Heatline F77 fault code information on this page is sourced and cross-checked against the official Heatline service / installation manuals for each affected model.
- Heatline CaprizPlus 28 manual (PDF)
- Heatline CaprizPlus 24a manual (PDF)
- Heatline Compact 24 manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026