Medium
On / Off (Demand fault) on Worcester Bosch Greenstar i Junior

Your boiler is receiving a signal to turn on even though your thermostat or timer is not asking for heating or hot water, which may keep the boiler running unnecessarily.

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

Boiler operating without live demand at ST10-LR (from external roomstat timer). Check for low voltage return at ST10-LR from older thermostats or permanent live from another source.

Engineer required

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

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