It’s automatic. You set the Rh you want. Once it reaches the rh you want it turns offf. If it falls below it turns on. Light can be turned off. The most had the adjustment. Low medium high. I rate it a 9/10. It loses a point cuz I set it 5 rh lower than what I desire Cuz I feel like the gauge on the humidifier reads 5 less rh than the indoor thermometer. Example I’ll set it to 55 rh, my thermometer reads 50 rh. I turn it up 5 rh higher on the humidifier problem fixed. Although that has a lot to do with optimizing your air flow. Which is one thing I’m working on.