The Evap40 Whole Room Evaporative Vortex Humidifier creates a comfortable, perfectly humidified living space quickly and quietly. Vornado's deep pitch blades pull large volumes of harsh, dry air through two humidifying filters. Then, using Vornado's signature Vortex Action, circulates the humidified air throughout the room. This provides complete and uniform humidification in spaces up to 1,000 sq. ft. The Evap40 delivers automatic humidity control with a built-in humidistat. An easy-to-use control panel allows you to choose your desired humidity level and fan speed (low, medium, or high). Its extra-large 4 gallon capacity provides up to a 4 gallon water output every 24 hours when operated continuously on high. This allows for long, uninterrupted operation and fewer refills.