Medium Warning
60:20 on Viessmann Vitodens 200-W

Your boiler is getting too hot while trying to heat your water, which usually means the heat isn't being transferred to your hot water tank quickly enough.

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

During DHW loading, the boiler water temperature is max. 20K higher than set DHW temperature

What causes this fault?

This fault occurs when the water inside the boiler gets much hotter than the water in your tank, suggesting that heat is trapped and cannot circulate properly. The most common reason is a blockage or limescale buildup in the heat exchanger, or a failing diverter valve that is stuck and preventing the flow of hot water to your cylinder.

Engineer required

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

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Related fault codes

F2View →A9View →

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