Aprilaire Humidifiers provide humidity in the form of pure water vapor to prevent minerals from entering the air stream. Water is supplied to the distribution tray and flow evenly across the Water Panel. Heat from the heating system causes the water to evaporate. Properly humidified air (vapor) is then distributed throughout your entire home. Call Nortek Environmental, Inc. at (630) 548-1500 for all of your HEATING, COOLING AND INDOOR AIR QUALITY NEEDS.