Medium
No code 213 on Worcester Bosch Greenstar 12i System

Your boiler is struggling because the water leaving the heater is much hotter than the water returning from your radiators, indicating a lack of flow through your heating system.

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

Temperature difference between supply and return exceeding limit

DIY fix possible

Check that all radiator valves (TRVs) are fully open to allow water to circulate freelyEnsure your system pressure is at the correct level, typically between 1 and 1.5 barBleed all radiators in the house to remove trapped air that may be blocking the flow

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