Medium Information
S.14 on Vaillant ecoTEC Pro / ecoTEC Plus

Your boiler is confused and thinks you are asking for hot water even though your taps are turned off, preventing the heating from starting.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

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

Hot water demand via fan sensor error

What causes this fault?

This fault occurs when the boiler's internal flow sensor incorrectly detects that water is running through the hot water pipes, even when all your taps are closed. The most common reason is a sticking internal component or a faulty sensor that is sending a false signal to the boiler's brain. Because the boiler thinks you are prioritising a hot bath or shower, it refuses to switch over to provide heat for your radiators.

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.22View →F.75View →S.10View →

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