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

Your boiler is failing to switch on for heating even though your hot water is working perfectly fine.

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 not operating during central heating demand (HW ok). Check: Live demand at ST10-LR, Facia mounted timer, CH knob in winter position, Diverter valve, Control board.

Engineer required

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

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