Michael L Klaus

US Patent:

52920631, Mar 8, 1994

Filed:

Feb 4, 1992

Appl. No.:

7/830623

Inventors:

Michael J. Klaus - Watertown WI

Assignee:

Johnson Service Company - Milwaukee WI

International Classification:

G05D 2300

US Classification:

236 1G

Abstract:

A stack damper control apparatus for positioning a stack damper and controlling a fuel source in response to closing of a temperature sensitive switch. Limit switches comprising drop cams are coupled to the drive shaft of the damper. In response to a call for heat, a motor turns the damper, coupling a source of energy to a fuel source when the damper is open and the limit switches transfer. A relay coil is energized to hold open a switch providing a parallel energization path for the motor. When the call for heat has been met and the temperature sensitive switch opens, the relay de-energizes closing the parallel energizing path and allowing the motor to close the damper. Provision is made for a safety interlock to ensure the fuel source is not activated when the damper is closed. Provision is also made for interface to a blocked vent shutoff system.