How Does the Aprilaire 700 Fan Powered Humidifier Work? What is included with the Aprilaire 700 humidifier? Get a quick and informative overview here! The Aprilaire 700 Whole Home Humidifier is a fan -powered humidifier that uses the heat from your furnace and it’s own fan to push humidified air through your vents and into your home. This unit can humidify up to 4,200 sq feet and deliver up to 18 gallons of water per day! The unit measures 18″ high by 15 29/32″ wide by 10 11/32″ inches deep and requires a plenum opening of 14 3/4″ by 14 5/16″.