Vitodens 100-W WB1B (Heating water too hot)

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Hi,

I've got a Vitodens 100 WB1B (i would say it doesn't have an outside sensor), when water for heating starts heating, the power is always on MAX (it doesn't matter which one is set 1-6). And the water is always heated to the MAX temperature (80°C)

I even tried to do the Set maximum heating input. I can get it to the high-fire test, but when I rotate the water temperature selector, the screen does the water heating - not the icon -.-.-