Medium
F.86 on Vaillant ecoFIT Pure 825

Your boiler has detected that the external safety switch connected to an underfloor heating system is signaling a fault or that the connection is open.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description

Fault: Underfloor heating contact

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

F.85View →

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