Frost protection display
Ventilation units with an internal PTC heat register keep the heat exchanger free from frost.
You can see under Ventilation/ventilation settings whether the PTC heat register is switched on or off (active/inactive).
Frost protection active: Frost protection equipment switched on. The outside air is warmed to avoid icing of the heat exchanger.
Frost protection inactive: Frost protection equipment switched off. No pre-heating of the outside air.