The most comfortable RH (Relative Humidity) level range is between 40% to 60%. For your health and comfort, when no target RH is selected, Philips Humidifier humidifies the air continuously and automatically stops once 70% RH level is reached. When environmental RH is lower than 70%, the appliance will resume according to previous settings.
When the target RH is selected, the appliance also automatically stops once the selected target RH is reached. When environmental RH falls below the selected target RH, the appliance will resume according to previous settings.