Abstract: An impedance heating system generally includes an outer tubular member having a first end and a second end, and an inner tubular member having a first end and a second end positioned coaxially inside the outer member. The inner member extends substantially the entire length of the outer member such that the first and second ends of the inner member terminate in close proximity to the first and second ends of the outer member, respectively. A power source is electrically connected to the first end of the inner member for supplying current to the inner member upon energization of the impedance heating system. A return path for current flow from the inner member to the power source generally includes either the outer member or a return cable electrically connected to the inner member. One or more spacer members are secured around the circumference of the inner member at spaced-apart intervals.

Abstract: A structure is provided for supporting at least one heating element inside an electric heater housing. To produce the support structure, a web is cut out of a metal sheet that includes a rectangular member, one or more support brackets and a neck portion connecting each support bracket to one side of the rectangular member. The support rail is formed by bending the rectangular along its longitudinal median into an L-shape configuration with a first portion integrally formed with a second portion in a perpendicular relationship. The first portion is secured to the electric heater housing. The second portion extends inwardly in the electric heater housing. The neck portions extend inwardly from the second portion, and are twisted approximately 90.degree. with respect to the support rail. The support brackets extend inwardly from each neck portion. Each support bracket has one or more openings formed therein, each adapted to receive electrical insulating means, such as coil bushings.

Abstract: A temperature controller with an integral liquid level control is contained within one unit. The unit consists of an electrical and heat conductive housing, which serves as a first electrode of the liquid level sensor. A metal clamp and a means to attach the housing to the liquid vessel is insulated from the housing and serves as a second electrode. The electrodes are connected in an electrical circuit such that when the electrodes are immersed within a conductive liquid, the resistance between the electrodes is reduced and a current is allowed to flow. A temperature sensor, such as a thermistor, RTD, or thermocouple, is contained within the housing. The housing conducts heat from the housing environment for radiation within the housing.

Abstract: A temperature controller with an integral liquid level control contained within one unit. The unit consists of an electrical and heat conductive housing, which serves as a first electrode of the liquid level sensor. A metal clamp and a means to attach the housing to the liquid vessel is insulated from the housing and serves as a second electrode. The electrodes are connected in an electrical circuit such that when the electrodes are immersed within a conductive liquid the resistance between the electrodes is reduced and a current is allowed to flow. A temperature sensor, such as, a thermistor, RTD, or thermocouple, is contained within the housing. The housing conducts heat from the housing environment for radiation within the housing.

Abstract: This duct heater assembly includes a duct section having upper and lower wall portions and opposed side portions. The upper and lower portions include end margin portions connectible to the end margins of conventional duct line section by "S" strip connectors. The side portions include C-shaped flanges connectible to the C-shaped flanges of conventional duct line sections by "C" strip connectors. One of the side portions incorporates a control box having an overhanging end spaced from the side wall of an adjacent conventional duct line section to accommodate the "C" strip connectors.