Medium
40-50-80 (ll-ll-ll) on Ariston Clas HE 24

Your boiler is struggling to detect the temperature of the water being used for your taps, which is preventing it from heating your water properly.

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

Thermistor «comfort» (open circuit)

Engineer required

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

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