Abstract: Each longitudinal section of a concentric direct vent duct structure for a fuel-fired appliance, such as a furnace, is formed using a tubular outer duct having an axially spaced pair of triangular stand-off frame members anchored therein, and a smaller diameter inner duct having an axially spaced pair of ramped external annular locking projections thereon. To assemble the concentric duct section, the inner duct is simply axially inserted into the outer duct. As the inner duct is inserted into the outer duct, a ramped annular side surface on the leading inner duct locking projection resiliently and radially outwardly deflects side wall portions of the stand-off frame members and then permits them to snap back to their original undeflected positions.

Abstract: A sheet metal colinear-to-coaxial duct transition assembly for a fuel-fired, direct vent heating appliance is fabricated by providing a one-piece rectangular sheet metal plenum box having a rear wall with first and second circular openings therein, and an open front side. A separate rectangular front wall of the plenum box is also formed and has a circular opening therein. Prior to assembling the plenum box, a rearwardly projecting combustion air stub duct is secured to the rear plenum box wall at the first opening therein, and a forwardly projecting combustion air intake duct is secured to the front plenum box wall at the opening therein. Cooperating side edge portions and flange pockets on the front wall and the open side of the plenum box and then interlocked and crimped to complete the plenum box.

Abstract: A fuel-fired fireplace insert has a compact combination heat exchanger/draft hood structure extending interiorly along its top side and opening outwardly through an upwardly extending flue gas outlet and a dilution air inlet disposed on a top front side portion of the insert. During insert operation, hot combustion gas generated within its fire box portion flows upwardly into the interior of the heat exchanger/draft hood structure, is cooled by room air entering the dilution air inlet, and is discharged through the flue gas outlet. At the same time, room air enters the insert through an opening on a lower front side thereof, is heated by being passed externally along the fire box and the combination heat exchanger/draft hood structure, and is then discharged from the insert back into the room through openings adjacent the dilution air opening.

Abstract: A double wall vent pipe is provided which comprises a first tubular wall that is helically corrugated to form radially outermost ridges spiraled around the outside of the first tubular wall and corresponding first recesses spiraled between the outermost ridges. The vent pipe also comprises a second tubular wall slidably disposed in a concentric relationship with the first tubular wall. The second tubular wall is helically corrugated to form radially innermost ridges which spiral around the inside of the second tubular wall and corresponding second recesses spiral between the innermost ridges. The radially innermost ridges are oriented in a direction oblique to the orientation of the radially outermost ridges such that a space between the first wall and the second wall will be maintained within the first recesses and the second recesses regardless of any bending of the vent pipe.

Abstract: The adjustable pipe fitting of the invention has double walls in accordance with Type B standards established by the American National Standards Institute and Underwriters Laboratories. In the preferred embodiment, the invention comprises a main conduit having three sections which are rotatably coupled together. A branch conduit is securely connected to the main conduit so that fluid communication exists between the branch and main conduits. The branch conduit also comprises three sections which are rotatably coupled together. The main conduit sections and the branch sections are coupled together at oblique angles relative to their respective longitudinal axes to provide a means for adjusting the fitting to accommodate connector pipes having various angles and orientations.

Abstract: An inexpensive and easily maintained gas burner assembly achieves the manufacturing and maintenance advantages of the conventional sand pan burner design in addition to the heat output and fuel efficiency of more complex burner designs. The invention comprises a tray having a bottom wall and sidewalls defining an interior and an open top. A cover channel having a midsection segment and at least two downwardly depending flanges is adapted to fit in the interior of the tray to form a mixing chamber between the cover channel and the tray. The downwardly depending flanges are spaced away from the sidewalls of the tray to form gaps suitable for filling with a noncombustible granular substance, such as sand or crushed pumice stone. The cover channel additionally comprises at least one projection extending above the top segment and defining at least one burner port. The projection is preferably a longitudinal ridge defining a plurality of burner ports.

Abstract: A thermally controlled damper construction for a gas fired combustion apparatus such as a furnace, water heater or the like, is described. The damper is pivotally mounted within the stack of the combustion apparatus for pivotal movement from a closed position to a full open position. A thermally responsive device is disposed in the stack on the upstream side of the damper for opening and closing the damper in response to predetermined temperatures. The thermally responsive device comprises a shaft mounted in the stack which extends thereacross and which has the damper rotatably mounted thereon. A helical bi-metal element embraces the shaft between the ends thereof and comprises first and second bi-metal members which are secured together in an end-to-end relationship.

Abstract: A thermally controlled damper construction for a gas fired combustion apparatus such as a furnace or the like is described. A damper is pivotally mounted within the stack or flue of the combustion apparatus for pivotal movement from a closed position, wherein the damper is located at an acute angle with respect to the axis of the stack, to a full open position. One edge of the damper is recessed to provide a vent opening between the damper and the stack to permit the venting of gases generated by operation of the pilot light during periods when the furnace is not operating. The damper is pivotally moved between its closed and open positions by a bi-metallic thermally responsive element which is located upstream of the damper and which is connected to the damper by means of a linkage. The linkage includes means for permitting the unrestrained rotational movement of the bi-metallic element after the damper is in its position thereby preventing stressing of the thermally responsive element at high temperatures.

Abstract: A thermally controlled damper construction for a gas fired combustion apparatus, such as a furnace. The damper has a generally eliptical shape and is mounted on a shaft in the stack or flue for pivotal movement from a closed position, where the damper is located at an angle of approximately 45.degree. with respect to the axis of the stack, to a full open position. One edge of the damper is recessed to provide a vent opening between the damper and the stack and permit venting of gases generated by operation of the pilot light during periods when the furnace is not operating. The damper is moved between the closed and open positions by a bi-metallic element which is located upstream of the damper and connected to the damper by a linkage. When the furnace is operated, the increase in flue temperature will operate the bi-metallic element to move the damper to the open position.