When in heating mode, people are confined indoors with unusually dry air for extended periods each year. Humidifiers help to keep comfortable levels of moisture, and properly maintained levels of humidity are beneficial for your respiratory system. Whole-house humidifiers work like your more typical room humidifiers. They put moisture into the air, making harsh, dry air much easier to breathe. And whole-house humidifiers help make the whole house comfortable, no more lugging a humidifier from room to room, spilling water on the floor as you go.