Automatic flue damper

In an automatic damper mechanism for retrofit installation in the flue of a combustion apparatus of the type comprising a valve for regulating the flow of fuel for combustion therein, said valve having a pair of valve terminals, and comprising a thermostat having a thermostat switch in series with a voltage source for regulating the operation of said combustion apparatus in response to heat demand, said voltage source having end terminals, said thermostat switch and said voltage source disposed in series between terminals of said thermostat;

• the improvement comprising a circuit board having at least four terminals, a first pair of said circuit board terminals for electrical connection respectively to said valve terminals, one terminal of said first pair and a third of said circuit board terminals comprising a second pair of terminals for electrical connection respectively to said thermostat terminals, an electric signal device, means electrically connecting said signal device between a remaining one of said circuit board terminals and said one terminal, and a wire connected at one end to said remaining one of said terminals, the other end of said wire movable for selective connection to opposite end terminals of said voltage source whereby upon touching said other end successively to said end terminals an installer may locate for permanent connection of said other end that end terminal which most steadily energizes said signal device.

An automatic damper mechanism for installation into the vent stack of a combustion apparatus for satisfying the heat demand of a thermostat switch comprising, in combination:

• a damper housing;
• a damper mounted in said housing for movement between a first position opening said housing for the passage of gases therethrough and a second position substantially closing said housing;
• yieldable means for biasing said damper to said first position;
• electrical solenoid means for moving said damper against the bias of said yieldable means to said second position, said housing including bumper means engaged by said damper to locate said second position;
• means for exerting a drag upon the movement of said damper to prevent bouncing of said damper against said bumper means;
• and
• a safety circuit for electrically connecting said solenoid in series with a source of power for operating said solenoid, said safety circuit including first switch means for interrupting the continuity thereof, said damper mechanism including a relay, means for electrical attachment of said relay to said thermostatic switch so that said relay is energized upon closure of said thermostatic switch, said first switch means responsive to said relay so that said first switch means is opened by said relay upon closure of said thermostatic switch;
• said safety circuit including second switch means, said damper mechanism including a heat sensor disposed in said housing for opening said second switch in response to elevated temperatures in said housing, said damper having an opening therethrough for inducing gases seeking to escape said housing to flow adjacent said heat sensor;
• said safety circuit including third switch means, and means responsive to the pressure of fuel passing to said combustion apparatus for opening said third switch means when fuel passes to said combustion apparatus.

An automatic damper mechanism for installation into the vent stack of a combustion apparatus for satisfying the heat demand of a thermostat switch comprising, in combination:

• a damper housing;
• a damper mounted in said housing for movement between a first position opening said housing for the passage of gases therethrough and a second position substantially closing said housing;
• yieldable means for biasing said damper to said first position;
• electrical solenoid means for moving said damper against the bias of said yieldable means to said second position, said housing including bumper means engaged by said damper to locate said second position;
• means for exerting a drag upon the movement of said damper to prevent bouncing of said damper against said bumper means;
• and
• a safety circuit for electrically connecting said solenoid means in series with a source of power for operating said solenoid means, said safety circuit including first switch means for interrupting the continuity thereof, said damper mechanism including a relay, means for electrical attachment of said relay to said thermostatic switch so that said relay is energized upon closure of said thermostatic switch, said first switch means responsive to said relay so that said first switch means is switched by said relay upon closure of said thermostatic switch;
• said safety circuit including second switch means, said damper mechanism including a heat sensor disposed in said housing for opening said second switch in response to elevated temperatures in said housing, said damper having an opening therethrough for inducing gases seeking to escape said housing to flow adjacent said heat sensor;
• said safety circuit including third switch means, and means responsive to the pressure of fuel passing to said combustion apparatus for switching said third switch means when fuel passes to said combustion apparatus.