Medium
H.01 – .21 on Baxi Assure

Your boiler is heating up too quickly when you turn on the hot water, likely because the water isn't flowing through the system fast enough.

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

Ensure all internal stopcocks and the main water supply valve are fully openCheck for any visible leaks around the boiler or pipeworkRestart the boiler to see if the temporary fault clears

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