Abstract: A venting system for gas fired heating plants including a diverter box, conduit means for conducting gas from one heating plant upwardly in one leg of an inverted U pattern and downwardly into the second leg of such pattern while admitting air at the bottom of the box to form a heat lock to restrict the flow of air in this pattern, and a second conduit means for conducting gas from a second heating plant upwardly and then downwardly of the second leg of the pattern for the first heating plant to a level at which gas may be passed within the box from the inlet to the outlet of the box, thus providing a structure which avoids the blowing out of the pilot flame in one or another of the heating plants.

Abstract: An apparatus for opening and closing the draft hood discharge opening and vent and fuel line of a fluid fuel-fired heating device such as a domestic water heater. The disclosed apparatus includes a diaphragm-type expansible chamber fluid motor assembly mechanically linked to a damper assembly such that when the heating devices call for heating, the supply of pressurized fuel acts to actuate the motor for opening the damper assembly. The motor assembly also has a pressure output line which operates a fail-safe type of diaphragm valve for controlling flow. This prevents burner operation until after the dampers are open. Additionally, when the supply of fuel is terminated, the motor assembly does not close the damper assembly until after the diaphragm valve stops fuel to the burner.

Abstract: An improved flue damper for isolating furnace from chimney-flue when burner is not operating includes in preferred embodiment a damper plate pivotally mounted within a flue section on a control rod extending through the flue section to bearing support in a bracket spaced from the flue section by a frame affixed to the flue section exterior; a bimetallic strip spiral having inner end affixed on the control rod and outer end detachably looped over a stud extending from the frame rotates the control rod under thermal actuation provided by an electric heating element adjacent the bimetallic strip spiral; a damper control strip on the end of the control rod adjustably affixes a switch plate rotatable therewith and bearing a first mercury switch controlling the heating element circuit and a second mercury switch controlling the furnace burner circuit; stop structure on the bracket limits rotation of the damper control strip and control rod.

Abstract: This flue control assembly is for use with a combustion chamber, such as an oven, having a thermostatically controlled burner valve circuit and includes a damper pivotally mounted in the oven flue for rotation between open and closed positions by an air actuated, movable arm assembly. The air actuated arm assembly is supplied with air from a valve controlled air pump and the valve includes a movable valve element which is resiliently connected to the movable arm and the movable valve element is moved into position to condition the supply of air from the pump by movement of the damper. An electrical switching system connected to the burner valve circuit ensures that the burner valve cannot be actuated unless the damper is in the open position in the flue.

Abstract: A relatively simple automatic mechanical flue damper is provided by a damper plate having a slot extending across a major portion of its diameter with a helically-shaped, temperature responsive bimetal having one end attached to the damper plate at one end of the slot, and its other end attached to a bushing which in turn is fixed relative to the flue in which the damper is situate, with a shaft extending in rotatable relation through a bore in the bushing and having its end opposite the bushing attached to the damper plate, the helical bimetal being responsive to changes in flue gas temperature to rotate the damper plate between predetermined open and closed positions with the shaft rotating to corresponding positions, and at least one of the shaft ends including indicia means to permit observation of shaft and damper rotative position.

Abstract: A draft control arrangement having bimetallic damper elements mounted in a draft hood and adapted to change shape in response to temperature change to open and close the flow passage for vent gases from a combustion apparatus. The damper elements are positioned in the hood relatively close to the source of hot flue gases to provide faster opening and less tendency for vent gas spillage. When open the damper elements cooperate with stationary walls of the draft hood so that the resulting streamlined passage presents minimum flow resistance. In certain embodiments the damper elements are arranged to undergo a spreading action during opening movement to achieve a disproportionately large passage for the vent gases during the initial phase of opening. In another embodiment a damper unit is mounted separate from the draft hood and provides the same operating results as the other embodiments.

Abstract: Apparatus and a method for assuring safe retrofit installation of a flue damper in a hot air furnace. The flue damper is electrically connected to the original furnace control circuit by engaging a flue damper connector with a portion of a printed circuit board containing part of the furnace control circuit. The physical configuration of the adapter and the printed circuit board require removal of a jumper conductor within the printed circuit board prior to connection of the adapter thereby assuring that the flue damper is correctly installed so that it will be in the open position before the furnace may be ignited.

Abstract: An improvement in space heating furnaces fueled by gas or liquid for saving heat ordinarily lost through the draft system of such a furnace, comprises a means of automatically closing the air inlet to the combustion chamber as well as the air inlet to the diverter air opening at the flue immediately after cessation of the main burner flame, and also for opening both of the air inlets immediately prior to the ignition of the main burners.

Abstract: In a fired furnace system having a convection section, and in which control a furnace draft is vital to both fuel conservation and avoidance of furnace damage, apparatus for monitoring the pressure conditions (draft) inside the furnace comprises a first pressure sensor means positioned at the arch (roof) of the furnace, a second pressure sensor means inside the furnace downstream from the convection section, and differential pressure measuring means connected between the first and second means for constantly measuring the pressure drop through the convection section.

Abstract: In a fuel-burning device having a combustion chamber, a burner with a control, an exhaust stack connected to said chamber, an air diverter in said stack and a thermostat connected to said burner control; the improvement which comprises a damper section in the stack downstream of the diverter. The damper is disposed within and journalled upon bearings attached to the damper section. A motor on the damper section has an output shaft connected to the damper and includes a rotary switch on said shaft. An electrical circuit includes a relay switch interconnecting the thermostat, burner control, motor and rotary switch. The motor output shaft is intermittently rotatable through successive arcs of 90.degree., through 360.degree., whereby the damper normally closes the stack preventing escape of room air therethrough when the burner is not operating. The thermostat, when calling for heat, closes the circuit to the motor rotating the damper 90.degree. to open position and successively energizing the burner.

Abstract: A venting system for the combustion chamber of a gas-fired heating plant has an elongate diverter box arranged vertically of the heating plant exteriorly thereof and having an upper portion and a lower portion with the latter having a bottom provided with a substantial opening disposed well above the base of the heating plant for the free admission of atmospheric air surrounding the heating plant into the diverter box and with the upper portion having selected openings for the reception of horizontally disposed pipings from the flue outlet for the combustion chamber and for the chimney flue with a vertical baffle depending from the closed top of the upper portion a substantial vertical extent into the diverter box and dividing it into a flue outlet section and a chimney flue section with said sections having thermostat means to indicate exteriorly of the sections the temperature of the gases therein and with a safety limit switch housed in the flue outlet section below the lower free end of the baffle and bei

Abstract: A flue damper to control the exhaust flow in a flue, wherein a flue damper plate is movable from an open position to a closed position by a solenoid operated plunger and returned from the closed position to the open position by a biasing spring. A damper arm actuates a normally-open limit switch closing the limit switch contacts. The limit switch is in series with normally open contacts of a thermostat, fuel valve, and power source, establishing a fuel system circuit. When the damper plate is in the closed position, the limit switch contacts are open and the fuel system circuit is broken. The plunger solenoid is connected in series with normally closed contacts of the thermostat, and power source, establishing an electrical circuit to close the damper plate. Thus, the circuit to close the damper plate and the fuel system circuit are mutually exclusive so that fuel may not be fired within the flue when the damper plate is closed.

Abstract: An apparatus for opening and closing the draft hood discharge opening and vent and fuel line of a fluid fuel-fired heating device such as a domestic water heater. The disclosed apparatus includes a diaphragm-type expansible chamber fluid motor assembly positioned in the burner fuel supply line. The motor assembly is mechanically linked to a damper assembly such that the supply of pressurized fuel acts to actuate the motor for opening the damper assembly prior to the motor assembly admitting fuel to the burner. Additionally, when the supply of fuel is terminated, the motor assembly does not close the damper assembly until after the motor assembly stops fuel to the burner.

Abstract: A flue gate device operated by a solenoid whose energy comes from any outside source, which energy is controlled by the furnace burner control of the furnace to which it is attached. The pull of the solenoid is resisted by a spring which will restore the flue gate to an open position when the solenoid is deenergized or in case of an electrical failure in the flue gate device itself. Through relay switches, the solenoid is deenergized when the furnace burner is energized, and the solenoid is energized when the burner is deenergized, thus enabling a "fail-safe" condition, which enables the furnace to function completely free of the flue gate device.

Abstract: A venting system for a warm-air furnace, gasfired boiler or the like heating plant has an open bottom diverter box which is arranged horizontally externally of the heating plant substantially at the level of the top thereof. The top wall of the diverter box at one end section thereof is connected by a vertically upstanding U-shaped, internally unobstructed, ducting to the top of the combustion chamber of the heating plant so that fumes flow therethrough into such combustion chamber end section of the box while the top wall of the diverter box at the other end section is connected by a vertically upstanding, internally unobstructed, piping to the flue.

Abstract: In the heating chamber of the furnace are a number of heat-absorbing elements which serve as a thermal storage, absorbing some of the heat which is developed during the regular burning cycle and then releasing such heat for additional heating effect. Stored heat is available for additional and therefore more efficient heating. A control system is used to conserve heat by selectively and automatically opening and closing the stack to prevent heat loss in timed relation with the burning cycle and adapted to provide sufficient purge time. The stack valve opens automatically at the commencement of a burning cycle and thereafter automatically closes after a purge interval. In the event of a power failure, the stack valve automatically closes and reopens when power is restored prior to the commencement of any succeeding burning operation.

Abstract: A damper, normally biased closed, in a flue of a heating system has an arm which is connected by linkage to an armature of a solenoid for opening the damper when a winding of the solenoid is energized by a heating system control. Switch means, engaged by the arm, is interposed between the heating system control and burner facilities of the heating system for preventing operation of the burner facilities when the damper is closed and for allowing operation of the burner facilities when the damper is open.