The Trane Company

American Standard Inc.

Andrew J Schlangen

Jerry W McClead

Thomas A Garavalia

A controller for operating a two-speed fan motor at one of two speeds and for selecting the appropriate speed in response to conditions such as a maximum and minimum duct static pressure in a fan unit having moveable inlet guide vanes for controlling air flow rates through the fan unit when employed in a variable air volume system. Position sensing switches are provided on the fan unit for indicating to the controller when the inlet guide vanes are in their preferred switching positions, which may be full open or full closed. The controller then selects one of the two fan speeds as appropriate within an operating deadband limit which serves to prevent undesirable changes of motor speed.

Controller for two-speed fans in VAV systems having inlet vanes

A centrifugal blower for air conditioning applications is shown having an adjustable inlet guide vane control for a blower wheel having forwardly curved blades. The pivot axis of each inlet guide vane is substantially offset or displaced from the plane of the inlet guide vane.

Centrifugal blower control apparatus

An electric heater control circuit is shown which utilizes a 10-step controller for obtaining eighteen steps of heating control. Electrical and magnetic control circuitry operates this 10-step controller effectively through two cycles, one at a low level power output mode and a second at a high level power output mode, to thereby substantially increase the effective number of steps of heat control. In addition, means are provided for instantaneously energizing or de-energizing a plurality of small electric heaters upon shifting modes to compensate for the de-energization or energization respectively of a large heater to thereby avoid momentary periods of excess heat or cold while the controller is shifting modes.

Growing community of inventors

La Crescent, MN, United States of America

Andrew J Schlangen