The radiator actuator is equipped with an automatic "window open detection" which is switched off at the factory. As soon as the radiator actuator detects a cooling by more than 0.3°C within 2 minutes, this is evaluated as "window open" and the thermostat is closed. OPN (open) is shown in the display.
The radiator actuator must detect the cooling at its mounting location in order to use the function. Depending on the position of the radiator in the room, it may be that it becomes colder in the room, but the radiator actuator does not register this cooling. This may be the case, for example, if the radiator is located at a greater distance from the window or if the radiator is mounted in a niche.
The "Window open detection" can always be switched off in the menu. To do this, press the menu key and select the menu item dEt (Detection) with the Plus key and briefly press the menu key. Change the state with the Plus key and confirm with the Menu key. To exit the menu, press the menu key again.
Alternatively, the temperature can be lowered when the windows are open using external window/door contacts.