Abstract: A standoff comprising a handle that is adjustably associated with a bracket, with the handle self-latching in relation to bracket at a desired position and at a desired quantifiable torque in relation to the bracket.

Abstract: A data center, an air handling system, and a method for installing equipment in a data center enable internal differential pressure relief within the data center. A volumetric container has mounting location(s) for heat generating information technology (IT) component(s) positioned within the volumetric container. A cold aisle on one side and a hot aisle on another side of the IT component(s) that have air passages for air cooling. A cooling unit is coupled to the volumetric container to pressurize the cold aisle with supply air and draws return air from the hot aisle. An air barrier is attached across an air passage between the cold and the hot aisles. A differential pressure relief mechanism is attached to the air barrier. The differential pressure relief mechanism is configured to open in responses to an air pressure difference across the differential pressure relief mechanism exceeding a pressure threshold.

Abstract: A standoff regulator that has a handle that is adjustably associated with a bracket, with the handle self-latching in relation to the bracket at a desired position and at a desired quantifiable torque.

Abstract: A damper, damper kit and method are for installing a damper in a duct defining a gas conduit. The damper kit includes a first aperture closing unit engageable with at least one conduit wall and configured to close a first aperture when engaged therewith and including a shaft receiving section opened in the gas conduit. The damper kit has a second aperture closing unit engageable with the at least one conduit wall and including a shaft receiving section opened in the gas conduit. The damper kit includes a damper having at least one shaft with a first section insertable in the shaft receiving section of the first aperture closing unit and a second section insertable in the shaft receiving section of the second aperture closing unit and extending past the at least one conduit wall through the second aperture closing unit.

Abstract: This boiler has a flue in which a reducing agent supplying device and a selective reduction catalyst are provided, a bypass flow path bypassing economizers is provided, and a first closing device partially closing the bypass flow path and a second closing device partially closing the flue are also provided. A plurality of first closing members, serving as the first closing device, are provided along the direction in which exhaust gas flows through the flue at a predetermined spacing in the width direction of the flue. A plurality of second closing members, serving as the second closing device are provided along the vertical direction at a predetermined spacing in the width direction of the flue. The first closing members and the second closing members are arranged so as to be displaced from each other in the width direction of the flue.

Abstract: A snap-action valve assembly for an exhaust system and a method for manufacturing the same is provided. The valve assembly includes a first conduit and a second conduit that is partially received in the first conduit. A valve flap is disposed within the first conduit for controlling exhaust flow. A shaft supports the valve flap in the first conduit for rotation between open and closed positions. The first conduit has first and second slots, each extending from an open slot end to a closed slot end. First and second bushings supporting the shaft are disposed within the slots between the second conduit and the closed slot ends. A pad made of wire mesh is attached to the valve flap. The pad includes an end portion that contacts the first conduit in the closed position to dampen vibration and reduce valve flap flutter.

Abstract: A snap-action valve assembly for an exhaust system and a method for manufacturing the same is provided. The valve assembly includes a first conduit and a second conduit that is partially received in the first conduit. A valve flap is disposed within the first conduit for controlling exhaust flow. A shaft supports the valve flap in the first conduit for rotation between open and closed positions. The first conduit has first and second slots, each extending from an open slot end to a closed slot end. First and second bushings subassemblies supporting the shaft are disposed within the slots between the second conduit and the closed slot ends. Each of the first and second bushing subassemblies includes an alignment system in the form of protrusions that limit insertion of the first and second bushing subassemblies into the first and second slot to a single orientation.

Abstract: In a stack leading from a fired heater, a plurality of damper blades are positioned at a longitudinal location, each blade being at least partly rotatable around its longitudinal axis to regulate flow through the stack. A plurality of controllers is operatively associated with the plurality of parallel blades to effect rotation of the blades. At least one of the controllers is decoupled from the rest of the plurality of controllers and used to independently control at least one but not all of the plurality of damper blades. The damper blades can be parallel or opposed.

Abstract: An opening/closing valve structure for an engine is provided with a valve body for opening and closing an intake passage or an exhaust passage of the engine; a pair of bush members mounted on axial ends of the valve body; and a shaft member axially passing through one of the bush members and projecting from the bush member by a predetermined length within one end of the valve body. Each of the bush members is mounted in such a manner that a part of the bush member is axially received in an end of the valve body and the remaining part thereof axially projects from the end of the valve body. A portion of the shaft member projecting from the one of the bush members is connected to the valve body in such a manner that relative rotation of the shaft member with respect to the valve body is disabled.

Abstract: A damper mechanism restricting combustion and exhaust air flow in response to temperature changes in a direct vent sealed combustion gas fireplace is provided. The mechanism allows the fireplace to have unrestricted air flow when the fireplace is not on and to restrict the air flow when the fireplace is on. A bi-metallic temperature responsive element is used to move a restrictor element to restrict air flow allowing maximum air displacement during cold ignition and enhancing operating efficiency when the fireplace is on.

Abstract: An oven is provided including an oven cavity and an outlet duct for receiving exhaust gas from the oven cavity. The oven further includes a flow control device attached to the outlet duct. The flow control device includes a damper assembly positioned at least partially within the outlet duct. The damper assembly is movable with respect to the outlet duct. The flow control device further includes a drive unit attached to the damper assembly, the drive unit selectively moving the damper assembly between a closed position in which the damper assembly blocks a flow of the exhaust gas through the outlet duct and an opened position. The oven further includes a control system for controlling the damper assembly.

Abstract: A “rocket” stove that has a plurality of vertical cylindrical cavities containing a combustion chamber, a fuel compartment and a chimney. The vertical cylindrical cavities are connected to a hot-gas chamber where the gases are utilized to heat a hob used in the manner of a griddle. The hob has apertures over the vertical cylindrical cavities, over which the food containers to be heated are placed. The hot-gas chamber has an opening and an exhaust pipe for evacuating the gases from the environment where the stove is used. The stove has a thermal-insulation covering placed between the interior walls thereof and the exterior in order to prevent burns. The exhaust pipe prevents intoxication by smoke inhalation, which commonly arises when cooking over an open fire.

Abstract: A gaseous fuel fired furnace having a vapor condensing flue gas vent conduit, a flue gas flow restrictor disposed in the vapor condensing flue gas vent conduit having a flue gas upstream side and a flue gas downstream side, and a condensate bypass conduit extending around the flue gas flow restrictor having a condensate inlet in fluid communication with the flue gas downstream side of the flue gas flow restrictor and a condensate outlet in fluid communication with the flue gas upstream side of the flue gas flow restrictor.

Abstract: An exhaust stack for a combustion zone of a furnace includes a main stack having a first chamber therein in communication with the combustion zone, and a main damper disposed for movement within the first chamber to be positioned to provide a cross-section of the first chamber through which combustion products from the combustion zone may flow, and a secondary stack having a second chamber therein in communication with the first chamber and being disposed within the first chamber, the secondary stack having a second damper disposed for movement within the second chamber to be positioned to provide a cross-section of the second chamber through which the combustion products from the combustion zone may flow.

Abstract: The present invention relates generally to 90% Annual Fuel Utilization Efficiency gas or oil burning devices that depend on external air for combustion. More particularly it discloses an alternate intake apparatus for air for combustion that opens automatically when the inlet air conduit from outside is blocked or severely restricted.

Abstract: A unitary damper shaft extender for HVAC air ducts, the extender comprising a unitary apparatus comprised of two interlocked, but relatively movable members. One of the members being capable of interlocking with a damper shaft, and the second member being slidably movable to cover, and thereby lock the first member to the damper shaft, so as to extend its length beyond the usual insulation used for air ducts.

Abstract: The invention regards a non-return valve for a exhaust duct of flue gases of a boiler, comprising a valve body in which a passage opening of flue gases is defined, to said valve body a obturator being associated which, in a determined operating condition, closes said opening, said obturator comprising a first swing element, hinged on said valve body at said passage opening of flue gases. Advantageously, said obturator comprises a second swing element, hinged on said valve body at said passage opening of flue gases, said first and second swing elements being hinged at or in proximity to a middle plane of said opening.

Abstract: A damper regulator device for adjusting the orientation of a damper blade in an air transfer system, such as a duct, is disclosed. The regulator is coupled to an end portion, of a damper shaft, pivoting of a handle component of the regulator functioning to turn the shaft and hence the blade. The device is adjustable to accommodate damper shafts of different configurations and sizes without disassembly of the device by shifting the handle between one or another of a pair of slots disposed at disparate distances from the shaft. The shifting of the shaft between slots in effected by a channel extending between the slots.

Abstract: An exhaust duct orifice adjustment device for a gas-fired heater used to indirectly heat an oven communicating with a heat exchanger, wherein the exhaust duct includes a fixed annular orifice plate and a switch having a pressure sensor on opposed sides of the fixed orifice plate, turning off the burner if the pressure drop falls below a predetermined minimum. The orifice adjustment mechanism includes a moveable plate upstream of the fixed orifice plate having an opening communicating with the opening in the fixed orifice plate and an adjustment mechanism moving the orifice adjustment plate from a retracted position, wherein the opening through the fixed orifice plate is substantially unobstructed, to an extended position which restricts the opening through the fixed orifice plate, thereby adjusting the pressure drop.

Abstract: An exhaust duct orifice adjustment device for a gas-fired heater used to indirectly heat an oven communicating with a heat exchanger, wherein the exhaust duct includes a fixed annular orifice plate and a switch having a pressure sensor on opposed sides of the fixed orifice plate, turning off the burner if the pressure drop falls below a predetermined minimum. The orifice adjustment mechanism includes a moveable plate upstream of the fixed orifice plate having an opening communicating with the opening in the fixed orifice plate and an adjustment mechanism moving the orifice adjustment plate from a retracted position, wherein the opening through the fixed orifice plate is substantially unobstructed, to an extended position which restricts the opening through the fixed orifice plate, thereby adjusting the pressure drop.

Abstract: A barbeque grill including a lower housing, heating means and food support means positioned within the lower housing, an upper housing or hood adapted to enclose the lower housing, a smoke exhaust means provided in said upper and/or lower housing for allowing smoke to escape from within the barbeque grill, wherein said smoke exhaust means is retractable/collapsible in order to allow the oven or grill to take up the least amount of space when being stored or transported.

Abstract: The present invention is a mechanical draft controller. The draft controller is comprised of a draft controller portion, a means for pivoting the controller portion, and a means for counterbalancing the controller portion. The draft controller portion has a surface that is movable in a generally arcuate path with respect to a central axis, a second surface extending between the first surface and the central axis, and two side surfaces extending between the first surface and the central axis. The side surfaces are spaced apart and have the second surface oriented between the side surfaces.

Abstract: A gas-fired, simulated log fireplace insert incorporating an automatic flue damper for controlling the operational state of a chimney vent (open/closed) in response to gas combustion, an externally mounted carbon monoxide detector for terminating or inhibiting gas combustion in response to an unsafe level of detected carbon monoxide and a temperature actuated switch, disposed within the firebox area of the fireplace proximate the flue, for terminating gas combustion in response to excessive fireplace temperatures caused by a malfunctioning damper.

Abstract: There are disclosed means and method for improving the efficiency of combustion in an automatic gas-fired furnace through retardation, without restriction of the exhaust emission of the products of combustion, which are caused to dwell longer in the combustion chamber to elevate the temperature, not only through the impoundment of what would otherwise be waste heat, but by the conversion of CO gas and excess air to CO.sub.2 gas, thus, reducing the two former, increasing the latter, along with temperature. This reduces the condensate in the exhaust chimney. An enlarged chamber in the exhaust gas conduit is incorporated within the line of exhaust flow from furnace to chimney. A baffle plate, approximately equal in area to the cross-sectional area of the conduit, is immovably secured in the chamber normal to the line of exhaust flow. The chamber is completely closed except for the exhaust flow entry and exit ports.

Abstract: A flue restrictor to control air flow in a combustion apparatus having an exhaust system that includes a flue. The restrictor has a housing to be attached in the flue. There is a first valve member located in the housing and a second valve member located in the housing. Each valve member is composed of open and closed areas, and cooperates with the other valve member to act as a valve. Movement of one valve member relative to the other controls air flow in the restrictor, and thus in the combustion apparatus. The restrictor provides sensitive control and ease of adjustment in position.

Abstract: An in-line power venter insertable into a vent pipe and having a housing attachable to the vent pipe. The housing has separate negative and positive pressure chambers provided by a separator plate positioned within the housing and having an opening for flow of gas to a blower wheel in the positive pressure chamber. The separator plate has a pair of generally semicircular, oppositely-extending sections disposed above the housing for insertion into the vent pipe to positively separate negative and positive pressure zones within the vent pipe. A flow-regulating plate for draft control is mounted within the housing and is manually-adjustable externally of the housing for movement toward and away from an opening in the separator plate to control the flow rate through the opening to the central area of the blower wheel.

Abstract: The invention provides a fuel saving device comprising a flue damper of simple mechanical construction mounted on a support member. A hinge connects the flue damper to the support member allowing the closure of the flue damper which is counter balanced when the furnace is shut down. When the furnace is on the gas flow opens the damper.

Abstract: This invention provides an adjustable damper having a tubular duct section defining first and second diametrically opposed openings and first and second sets of detents formed radially from the material of the duct about the respective openings to define a plurality of damper settings. The first detent set is offset angularly relative to the second detent set and a valve element is provided having a circular central portion proportioned to fit within the duct section. Diametrically opposed first and second shoulders project from the periphery of the disc and aligned first and second stub axles are formed from the material of the disc and depend from the respective first and second shoulders. These shoulders are engaged with the respective first and second sets of detents such that in any one selected angular position of the valve element, the element is located by engagement of one of the shoulders in one of the detents of the detent sets.

Abstract: A wood burning device comprising a metal box with a flue, an automatic flue damper, a combustion chamber formed by layers of insulating refractory material, a transparent ceramic glass front, an insulated refractory baffle forming the top portion of the combustion chamber, a means for introducing air into the combustion chamber, and a smoke deflector upstream from the flue. The stove further includes a support for tilting the box backwards, and a latching mechanism for a slideable door on the ceramic glass front.

Abstract: There is disclosed an extension apparatus for a damper assembly having an extension member for effectively extending the damper assembly control shaft and a securing member for securing the extension member onto the control shaft.

Abstract: Disclosed herein is a preferred process for making a catalyst. A catalyst such as is named in the title of this invention. The process begins with the chosing and blending the different refractories in order to necessitate the longevity of the damper. The mixing of the materials, with water, to the right consistency is very important in this process. To much moisture in the material will not provide the necessary porosity the catalyst needs. After mixing, the dampened material is placed into a two piece break away mold and pressed into the desired shape, size and density. The proper amount of curing time and the damp cool area in which the curing is to take place also adds to the longevity of the damper. The object of this invention is to provide an inexpensive process that doesn't require heat, for manufacturing a catalyst that will not become contaminated or less active with use, but by it's causing a more complete combustion, will create a higher BTU output and a decrease in fuel consumption.

Abstract: A duct fitting for connecting a branch duct to a main duct including a tubular body having cutting teeth formed on one end thereof for cutting a hole in the main duct by pressing the cutting teeth against the main duct and rotating the tubular body about its longitudinal axis. Subsequent to cutting of the hole, the cutting teeth are bent into engagement with the interior of the main duct to squeezingly hold the main duct between the bent over teeth and a resiliently deflectable mounting flange provided on the tubular body. An air diversion scoop is mounted in the bore of the tubular body and is pivotably moved so that a portion of the scoop extends from the tubular body into the main duct.

Abstract: A combustor unit for a woodburning stove comprises a generally T-shaped flue assembly interiorly receiving a combustor having a catalyst to facilitate combustion of exhaust gases. The combustor is pivotal between a combustion position wherein the combustor is positioned across an exhaust passageway to an open position wherein the combustor is substantially removed from the exhaust gas stream and positioned within an access passageway.

Abstract: Apparatus for cooperation with an associated flue having a first axis extending away from a point proximate to an associated combustion chamber which includes a funnel shaped member having first and second ends. The second end is larger than the first end. A damper is disposed in the associated flue which has a generally central bore. The damper is mounted in the associated flue for rotation about a second axis which is generally perpendicular to the first axis and the funnel shaped member is mounted with the first end higher than the second end and with the second end extending into the damper. The mounting for the damper may comprise at least one rod shaped member extending through at least one wall of the associated flue. The mounting for the funnel shaped member may comprise a plurality of elongated members extending radially from the funnel shaped member to the associated flue.

Abstract: A damper for sealing and unsealing a vertical furnace exhaust flue pipe to minimize the escape of heat when the furnace is not operating is disclosed. The damper comprises a cylindrical body adapted to form a section of vertical flue pipe having inner and outer walls. The cylindrical body has a top opening and a bottom opening and at least one transverse hinge rod horizontally transversing the body carried by opposed apertures in opposing wall portions of the body, an annular rim mounted on the inner wall of the body and a pair of oppositely extending gull-wing shaped damper shutters pivotably mounted on said hinge rod. Each of the gull-wing shaped damper shutters have upper and lower surfaces, a lower section and an outer upper section, and in the closed condition the lower sections of the shutters extend upwardly and outwardly at approximately a 45.degree. angle with the outer upper sections of the shutters extending horizontally and slightly spaced from the inner walls of the damper section.

Abstract: A flue control device for slowing the rate at which heated exhaust gases rise through an exhaust stack comprises a cylindrical housing enclosed by end caps, with an offset inlet and outlet being positioned in opposite end caps. The interior of the housing defines a baffle chamber, and a baffle mechanism is positioned in the baffle chamber between the inlet and outlet. The baffle mechanism comprises two overlapping plates, each plate having a prominent flange extending in an upstream direction relative to the flow of gases through the baffle chamber. The flanges interrupt and slow the swirling circular flow of gases as they pass through the baffle chamber. The baffle and housing are of a size such that the cross-sectional area of the restricted portion of the housing adjacent the baffle is at least as large as the cross-sectional area of the exhaust stack.

Abstract: There is disclosed an improved flue box assembly for use in conjunction with a heating plant, the flue box having a housing with an interior diametric opening substantially greater than the exhaust gas inlet to and outlet from the interior of the housing, and provided with a damper plate being pivotally mounted within the housing and movable between an open position and a closed position, the damper plate further having a flue opening positioned therein, the improvement consisting of a cap pivotally mounted on the housing adjacent the outlet opening thereof, the cap adapted to pivotally move between a closed position occluding the outlet opening of the housing and an open position leaving the outlet opening unobstructed, and adjustable counterbalancing means associated with the cap for adjusting the relative pressure necessary to move the cap into an open and closed position respectively in relation to the force exerted by flue gases escaping through the outlet opening of the housing, thus providing for impro

Abstract: A flexible disk damper which is capable of providing tight seals for a large diameter opening over a wide range of temperatures. Disks are made sufficiently flexible to compensate for inherent warpage in the damper seat by using a steel with a higher yield strength. Additionally, a varying cross-sectional thickness of the flexible disk is provided to ensure that unit stress is not exceeded along any point of the radius of the flexible disk for the deformation required to provide a tight seal. A pneumatic cylinder is utilized to provide a constant pressure to the flexible disks. A damper seat is fabricated from a cut plate or flat bar which is formed in an annulus. A deflection cone is utilized to deflect flue gases. The flexible disk is coupled together by bolts which are disposed in holes sufficiently large to allow independent movement of the disks to maximize deflection.

Abstract: A safety stovepipe damper assembly designed for use with a conventional type stovepipe and damper as used on coal, wood, or waste burning stoves. Provisions are made for presetting the damper to a specific low fire or closed position. A latch is also provided to hold the damper at an open position when desired. A heat activated means of releasing the damper from an open damper position is contained within the safety assembly. When activated by abnormally high stovepipe temperatures, the damper returns by gravity to its preset or closed position. The safety assembly can be used on vertically or horizontally installed stovepipe and damper assemblies in all sizes.

Abstract: An add-on catalytic damper assembly is provided which is adapted to be positioned between the flue outlet pipe of a wood burning stove and the chimney pipe, and which provides catalytic combustion of the normally unburned portions of the flue gas. The assembly is of a very simple five part construction comprising upper and lower housing members adapted to be connected to the chimney and stove pipes, respectively; a plate nestingly mounted within the lower housing member and including a pair of side by side openings therein providing two paths for the flue gas; a catalytic converter mounted in one of the openings; and a damper plate mounted over the other opening and movable by means of an integral handle between blocking and unblocking positions.

Abstract: An afterburner for a wood stove for use as a retrofit assembly comprises a rectangular housing having openings in the upper and lower surfaces provided with cylindrical collars for cooperation with the flue duct and with the opening in the top of the wood stove respectively. The openings are positioned at the rear of the housing so as to provide a forward section spaced from the openings. A catalytic combuster mounted in a cylindrical support is movable from a position directly above the opening in the bottom surface into the front section by a manually operable handle extending through the front face of the housing. A baffle mounted on the support and arranged at a shallow angle to the horizontal overlies the major part of the combuster so as to direct gases into the front section of the housing for heat exchange contact with the walls thereof.

Abstract: A thermally operated vent damper wherein a flue pipe (12) mounts an eliptical damper plate (38) for rotation about a hollow rod (30). A slot (42) is formed in the damper plate (38) by bending a flange (44) perpendicular to the plane of the damper plate (38) and providing an opening for a coil (52) of bimetallic material. The coil (52) controls the movement of the damper plate between closed and opened positions responsive to temperature in the flue pipe (12). An opening (19) in the flue pipe adjacent to the coil (52) provides a means for maintaining the coil (52) temperature lower than the flue gas temperature and for controlling the opening of the damper plate in the flue pipe in inverse proportion to the draft therein. A second bimetallic coil (60) is mounted outside the flue pipe to relieve stresses on the first bimetallic coil during prolonged high temperature excursions within the flue pipe.

Abstract: A damper for sealing and unsealing a vertical furnace flue pipe to minimize the escape of heat when the furnace is not operating, the damper comprising a cylindrical body adapted to form a section of vertical flue pipe, the cylindrical body having a top opening and a bottom opening at least one transverse rod horizontally transversing the body and carried by opposed apertures in opposing wall portion of the body, a pair of oppositely extending gull-wing shaped damper shutters pivotally mounted on the rod and in the closed condition extending upwardly and outwardly to the inner surfaces of the cylindrical walls of the damper section, the lower edges of the wing sections engaging an annular rim mounted on the inner walls, the wings opening to a vertical position when the furnace is operating and closing by gravity when the furnace is not operating.

Abstract: A thermally actuated damper for insertion in the flue pipe of furnaces consists of a cylindrical section of pipe having a diametrically extending bar fixed across its interior. The bar supports a pair of identical, semi-circular vanes formed of a bi-metallic laminate which project in a common direction from the bar. When the furnace is operating the hot flue gases cause the vanes to bend into abutment with one another so that they extend longitudinally along the flue pipe and allow substantially unrestricted flow of vent gases. When the furnace is off the cooling blades bend outwardly, toward the walls of the flue pipe, substantially blocking the flow of gases through the flue so that the warm air from the heated space is not drawn up the flue.

Abstract: A draft control plate, which automatically opens or closes to provide efficient draft conditions in a furnace, is provided with both horizontal and vertical counterbalance devices which respectively permit adjustment of the initial position of the plate and the sensitivity of its movements. Initially, the plate is partially open where it remains while the furnace is operating under normal conditions. It is then capable of opening or closing in response to changes in the pressure differential across it. Preferably, the plate is horizontally mounted in an auxiliary flue channel which is adjacent to and in connection with the main flue of the furnace.

Abstract: Apparatus for cooperation with an associated flue having a first axis extending away from a point proximate to an associated combustion chamber which includes a funnel shaped member having first and second ends. The second end is larger than the first end. A damper is disposed in the associated flue which has a generally central bore. The damper is mounted in the associated flue for rotation about a second axis which is generally perpendicular to the first axis and the funnel shaped member is mounted with the first end higher than the second end and with the second end extending into the damper. The mounting for the damper may comprise at least one rod shaped member extending through at least one wall of the associated flue. The mounting for the funnel shaped member may comprise a plurality of elongated members extending radially from the funnel shaped member to the associated flue.

Abstract: A damper device insertable into a slotted duct or flue without cutting completely through the duct, including a sleeve conforming to the duct cross-section and adapted for insertion through the slot to nest within the un-cut duct portion. A damper plate with stiffener ribs is rotatably mounted within the sleeve. An apertured cover plate slightly larger than the duct slot size is located to overlap the slot for mounting the damper device to the duct, and a spacer plate may be placed intermediate and rigidly attached to the cover plate and the sleeve for reinforcing the support at one end of a damper shaft. The damper shaft may be rotated manually or by means of a motor mounted by a bracket to the cover plate.

Abstract: The present invention is directed to the provision of an improved stove insert for a fireplace opening, having means associated therewith for precisely controlling draft, thereby enabling the stove insert to be used for coal as well as wood.

Abstract: A draft limiting device for controlling the draft in a flue gas passage, includes a flap which is supported on a swing shaft in a secondary air inlet for swiveling movement between a closed position, at which the flap extends in a substantially vertical plane to block entry of air from a room into the secondary air inlet, and a fully open position at which the flap is displaced a certain angle about the axis of the swing shaft to admit air through the air inlet to the flue gas passage. A solid, semi-cylindrical member is fixed to the flap so that the center of radius of the member is parallel to the swing shaft axis, and the member extends on diametrically opposite sides of the swing shaft axis. The member thereby provides a restoring moment to the flap as the flap is moved in response to a differential pressure from the closed to the open position. The magnitude of the restoring moment is either constant or decreases as the flap moves in the direction from the closed to the open position.

Abstract: A flue control device for slowing the rate at which heated exhaust gases rise through an exhaust stack comprises a cylindrical housing enclosed by end caps, with an offset inlet and outlet being positioned in opposite end caps. The interior of the housing defines a baffle chamber, and a baffle mechanism is positioned in the baffle chamber between the inlet and outlet. The baffle mechanism comprises two overlapping plates, each plate having a prominent flange extending in an upstream direction relative to the flow of gases through the baffle chamber. The flanges interrupt and slow the swirling circular flow of gases as they pass through the baffle chamber. The baffle and housing are of a size such that the cross-sectional area of the restricted portion of the housing adjacent the baffle is at least as large as the cross-sectional area of the exhaust stack.