Abstract: An electronic level control structure for regulating a fluid level in a vessel, such as a humidifier tank. The electronic level control has at least two Teflon.RTM. coated probes for sensing fluid level in the tank and extending downwardly from a main body member. A downwardly extending sleeve positions about a portion of the upper regions of each of the probes. The Teflon.RTM. coating and the sleeve at the upper region of each probe inhibits the formation of scale between the probes at the upper end of each probe by preventing or minimizing the amount of contact by vaporous gases, mineral salts and other contaminants about the upper regions of each probe. This also prevents buildup of electrical conductive scale. In one embodiment, three probes of different lengths extend downwardly from a body member.

Abstract: A humidifier for use with a forced air heating system. The humidifier comprises a water reservoir in the form of a sealed container having a water inlet connection and suitable control means for maintaining the level of the water at a predetermined depth within the reservoir. An electric immersion type heater is also provided within the sealed container at a level which is normally below the water level and, when energized, heats the water to produce steam. The reservoir can be mounted completely external to a duct of the forced air heating system, but an inverted U-shaped tube having preparations along the base thereof is disposed within the duct and has its parallel legs passing through the duct and reservoir so as to communicate with the portion of the reservoir above the level of the water therein. As such, the steam passes through the U-shaped tube and out its perforations to thereby add moisture to the air passing through the duct.

Abstract: A humidifier unit is used with a forced air heating system and includes a water reservoir, a water inlet connection to the reservoir, control means for maintaining the water level at a predetermined depth, and a heat exchanger for heating the water to produce steam. This reservoir has a removable top plate for closing the open top defined by the upper edges of side and end walls. Horizontal flanges extend inward from the upper edges of the reservoir side and end walls and act as a gasket base. Lips extend upward from the inner edges of those horizontal flanges and act as an internal horizontal gasket retainer. Finally, flanges depend from all sides of the top plate and are positioned to surround the upper edges of the side walls and to act as an external horizontal gasket retainer.