If "MAX" is shown on the display of the radiator control, the valve on the radiator is completely open, which means that it is heating at full power. "MAX" is displayed when the temperature is set to over 28 degrees.

The symbol of a snowflake is displayed if the temperature is set to under 8 degrees or the "Heat off" period configured in the FRITZ!Box user interface applies. The radiator control's limescale protection function and frost protection function remain active.