Medium
H.01 – .21 on Baxi Suprima 60

Your boiler is overheating because water isn't moving through the system quickly enough when heating your water.

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

Temporary error – flow temperature increasing too fast in domestic hot water (DHW) mode, insufficient circulation or sensor error.

DIY fix possible

Check that your external pump is running and hasn't seizedEnsure all isolation valves under the boiler are fully openCheck that your cylinder thermostat is not set to an unusually high temperature

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