Furnace stack damper control apparatus

• US 4,439,139 A
• Filed: 02/26/1982
• Issued: 03/27/1984
• Est. Priority Date: 02/26/1982
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Torborg, Ralph H., Nelson, Lorne W.
• Primary Examiner(s): Barrett, Lee E.
• Application Number:
  US06/352,814
• Time in Patent Office: 760 Days
• Field of Search: 431/20, 236/1 G, 236/45, 236/46 R, 126/285 B, 165/12, 307/65, 307/66
• US Class Current: 431/20
• CPC Class Codes: F23N 2225/12 room temperature
• CPC Class Codes: F23N 2235/04 in stacks
• CPC Class Codes: F23N 2235/10 power assisted, e.g. using electric motors
• CPC Class Codes: F23N 2235/14 electromagnetically operated
• CPC Class Codes: F23N 3/085 using electrical or electromechanical means

Abstract

A furnace stack damper control apparatus has a motor for connection to a stack damper to open the damper upon a call for heat by a space thermostat. The motor is driven in a closed direction by electrical energization and in an open direction by a spring return. A relay having two normally open switches and a normally closed switch is energized when a space thermostat calls for heat. The normally closed switch then opens to allow the damper motor to open the damper by the spring return. The motor has an end switch having a normally open and a normally closed circuit. The normally open circuit is used with one of the normally open switches of the relay to energize a gas valve when the damper is open. The normally closed end switch is used to provide the energization circuit for the relay by the space thermostat and the relay is maintained energized when the damper is open by the other normally open switch of the relay connected in parallel to the normally closed end switch. The circuit provides for additional safety in that normal operation of the gas valve control apparatus does not take place if the normally open or normally closed end switches stick in either position.

Claims

1. A stack damper control apparatus adapted to be connected to a damper in the exhaust stack of a fuel burning temperature conditioning apparatus and connected to a space temperature responsive switch means and a source of power for energizing fuel control means comprising,

motor means having a first energization circuit and an output connected to said damper to drive said damper to a closed position upon energization of said motor means,

a spring return means connected to said motor means for driving said output to drive said damper to an open position,

relay means having second energization circuit and two normally open switch means and a normally closed switch means controlled thereby,

switch means connected to said output of said motor means having two circuits, a first of said two circuits of said switch means being closed when said motor is in an energized position and the damper is closed, and a second of said two circuits of said switch means being closed when said motor is in a de-energized position and said damper is open,

first circuit means including said first circuit of said switch means adapted to connect said second energization circuit of said relay means in series with the space temperature responsive switch means and the source of power whereby upon a call for heat by the responsive means, said relay means is energized,

second circuit means comprising said normally closed switch means adapted to connect said first energization circuit of said motor means to the source of power whereby upon said relay means being energized upon a call for heat by the responsive means, said motor means is de-energized and said spring return drives said output and said damper to an open position,

third circuit means comprising a first and a second of said normally open switch means and said second circuit of said switch means adapted to connect the fuel control means to the source of power for operating the temperature conditioning apparatus, and

fourth circuit means connecting said second of said normally open switch means in parallel with said first circuit of said switch means to maintain said relay means energized while the damper is open.

2. The invention of claim 1 wherein said switch means connected to said output of said motor is a snap acting switch which operates in the position of said output near the open position of the damper.

3. The invention of claim 1 wherein said motor means is an AC motor receiving power from an AC source of power.

4. The invention of claim 1 wherein said stack damper control apparatus has five circuit connection terminals, wherein a first is adapted to be connected to fuel control means, a second is adapted to be connected to one side of a source of power and to the fuel control means, a third and a fourth are adapted to be connected to a space temperature responsive switch means, and a fifth is adapted to be connected to the other side of the source of power.