The Aprilaire Model 800 Steam Humidifier is a self-contained device that takes clean tap water and boils it, using electrode technology, to create steam. The humidifier generates steam by energizing two electrodes that extend into a canister of water. Electrical current flowing between the electrodes causes the water to boil, creating steam. The steam flows through a hose and is injected into a moving airstream by the way of a distribution tube. The steam flows out of the distribution tube into the duct work through a series of tiny tubes which create an even, drip-free transfer of steam into the moving airstream.