The radiator control starts with the preheating phase at the "adaptive heating start" to reach the desired temperature by the specified time. When adaptive heating starts, the next switching time is highlighted in black on the display of the radiator control FRITZ!DECT 302.

This preheating phase starts a maximum of one hour before the set time. The exact start time varies depending on the current room temperature. For example, the preheating period starts earlier if the room temperature is significantly below the desired temperature. If the room temperature is only slightly below the desired temperature, the radiator control starts to preheat later because the difference between the actual room temperature and the desired temperature is smaller.

"Adaptive heating start" is automatically enabled when you set up the schedule. If you are using a FRITZ!Box with FRITZ!OS 7.50 or later, the adaptive heating start can be disabled on the profile page of the radiator control or the group under "Smart Home > Devices and Groups".