Damper actuator

A stack damper control apparatus, adapted for use with a damper in an exhaust stack of a fuel burning temperature conditioning system, for coupling an energy source to a source of fuel in response to a signal from a temperature sensitive switch, said apparatus comprising:

• motor means responsive to said signal and coupled to said damper for driving said damper between a substantially open and a substantially closed position;
• limit switch means coupled to said motor means for controlling the coupling of said energy source to said source of fuel when said motor means drives said damper to said open position, said limit switch means comprising first switch means responsive to said motor means for coupling said energy source to said motor means and second switch means responsive to said motor means for coupling said first switch means to said source of fuel, and third switch means responsive to said motor means for coupling said motor means to said first relay switch means when said damper is in said substantially closed position and coupling said motor means to said second relay switch means when said damper is not in said substantially closed position, wherein said first switch means couples said energy source to said motor means when said damper is not in said substantially open position and couples said energy source to said second switch means when said damper is in said substantially open position and said second switch means couples said first switch means to said source of fuel when said damper is in said substantially open position.

A damper actuator adapted for use with a damper in an exhaust stack of a temperature conditioning system and for coupling an electrical energy source to a fuel source in response to the closing of a temperature-sensitive switch, said damper actuator comprising;

• motor means coupled to said damper for rotating said damper between a substantially closed and a substantially open position;
• first switch means coupled to said damper for coupling said electrical energy source to said fuel source when said damper is in said substantially open position, sad first switch means having a first contact coupled to said motor means, and a common contact coupled to said electrical energy source, and a second contact;
• second switch means coupled to said damper for coupling said electrical energy source to said fuel source, said second switch means having a first contact, a common contact coupled to said second contact of said first switch means, and a second contact coupled to said fuel source, said first switch means and said second switch means coacting in response to said motor means to form an electrically conducting path between said temperature-sensitive switch and said fuel source when said damper is in said substantially open position;
• relay means coupled to said electrical energy source for coupling said motor means to said electrical energy source, said relay means comprising a coil means for storing energy, said coil means having a first contact and a second contact coupled to system ground, said relay means further comprising first relay switch means for coupling said electrical energy source to said coil means, sad first relay switch means having a first contact coupled to said electrical energy source, and a common contact coupled to said first contact of said coil means, said first relay switch means forming an electrically conducting path between said temperature-sensing switch and said coil means in response to said coil means storing energy, said relay means further comprising second relay switch means for coupling said electrical energy source to said motor means when said coil means does not store energy, said second relay switch means having a first contact coupled to said electrical energy source, a common contact coupled to said motor means and a second contact;
• and
• third switch means coupled to said damper for coupling said relay means to said motor means, said third switch means having a first contact coupled to said common contact of said first relay switch means, a common contact coupled to said first contact of said first switch means, and a second contact coupled to said common contact of said second relay switch means, said third switch means coacting with said first switch means to form an electrically conducting path between said electrical energy source and said coil means when said damper is substantially closed, and said third switch means coacting with said second relay switch means to form an electrically conducting path between said electrical energy source and said motor means when said damper is not fully closed and said coil means does not store energy.