Abstract: An illustrative example embodiment of a method of operating a furnace configured for heating a space to be occupied by at least one individual includes determining a rate of change of a flue gas temperature of a flue gas vented from the furnace, determining a difference between the determined rate of change and a predetermined acceptable rate for a current furnace operating condition, and adjusting at least one operation characteristic of the furnace based on the determined difference satisfying at least one predetermined criterion. In some situations, such as a heating cycle, the flue gas temperature is compared to maximum and minimum thresholds.

Abstract: A furnace with a baffle assembly including at least one horizontal gap, and a heating, ventilation, and/or air conditioning (HVAC) system incorporating the same are provided. The furnace includes a furnace heat exchanger, a baffle assembly, and a fan. The baffle assembly is disposed adjacent to the furnace heat exchanger. The fan is in airflow communication with the furnace heat exchanger. The baffle assembly may include a first side and a second side. Each of the first side and the second side may respectively include a first section and a second section. A horizontal gap may be disposed between the first section and the second section (e.g., on either or both of the first side and the second side). The horizontal gap(s) may increase the efficiency of the furnace and/or the HVAC system.

Abstract: A plate fin for a heat exchanger is provided including a base plate having a plurality of holes formed therein. The plate fin also includes a plurality of generally annular collars. Each collar is positioned substantially coaxially within one of the plurality of holes. The plurality of first collars is substantially less than the plurality of holes such that a portion of the plurality of holes does not have a collar arranged therein.

Abstract: A coupling to connect a primary heat exchanger to a condensing heat exchanger of a furnace includes a coupling box extending between a primary heat exchanger and a condensing heat exchanger. The coupling box defines a flow path for flue gas between a primary heat exchanger outlet and a condensing heat exchanger inlet. A tube sheet is located at a distance from the tube sheet in the coupling box. The liner and the tube sheet define an insulating liner space therebetween reducing condensation on the liner.

Abstract: An attachment between a heat exchanger and a cell panel of a furnace includes a cell panel including a plurality of cell panel openings and a heat exchanger having a plurality of cells. Each cell has a cell outlet insertable into a cell panel opening of the plurality of cell panel openings. A compressible gasket is insertable between the cell panel openings and the cell outlets and securable therein when the heat exchanger is secured to the cell panel. A crimping tool for securing a heat exchanger cell outlet to a cell panel of a furnace includes a male portion including a split die having two die halves and a die expander configured to separate the two die halves to engage an inner surface of the cell outlet. A female portion applies a force to the cell outlet to crimp the cell outlet to the cell panel.

Abstract: A compact furnace heat exchanger for a gas furnace is disclosed. The compact furnace heat exchanger may include a first pass having an inlet end, a second pass in fluid communication with the first pass through a first return bend, and a third pass having an outlet end and in fluid communication with the second pass through a second return bend. The third pass may further include a plurality of irregularities for optimizing performance of the compact furnace heat exchanger and the associated gas furnace.

Abstract: A plate fin for a heat exchanger is provided including a base plate having a plurality of holes formed therein. The plate fin also includes a plurality of generally annular collars. Each collar is positioned substantially coaxially within one of the plurality of holes. The plurality of first collars is substantially less than the plurality of holes such that a portion of the plurality of holes does not have a collar arranged therein.

Abstract: A primary heat exchanger for a furnace includes one or more passes and having a heat exchanger height. A ratio of heat exchanger efficiency to heat exchanger height is in the range of about 7.0 points per inch to about 8.1 points per inch. A furnace includes a burner for combusting a fuel and a primary heat exchanger operably connected to the burner. The primary heat exchanger includes one or more passes and has a heat exchanger height. A ratio of heat exchanger efficiency to heat exchanger height is in the range of about 7.0 points per inch to about 8.1 points per inch.

Abstract: An attachment between a heat exchanger and a cell panel of a furnace includes a cell panel including a plurality of cell panel openings and a heat exchanger having a plurality of cells. Each cell has a cell outlet insertable into a cell panel opening of the plurality of cell panel openings. A compressible gasket is insertable between the cell panel openings and the cell outlets and securable therein when the heat exchanger is secured to the cell panel. A crimping tool for securing a heat exchanger cell outlet to a cell panel of a furnace includes a male portion including a split die having two die halves and a die expander configured to separate the two die halves to engage an inner surface of the cell outlet. A female portion applies a force to the cell outlet to crimp the cell outlet to the cell panel.

Abstract: A coupling to connect a primary heat exchanger to a condensing heat exchanger of a furnace includes a coupling box extending between a primary heat exchanger and a condensing heat exchanger. The coupling box defines a flow path for flue gas between a primary heat exchanger outlet and a condensing heat exchanger inlet. A tube sheet is located at the condensing heat exchanger inlet and a liner is located at a distance from the tube sheet in the coupling box. The liner and the tube sheet define an insulating liner space therebetween reducing condensation on the liner.

Abstract: A heat exchanger system and a method of assembly is provided for a gas appliance such as a furnace. The heat exchanger system includes an attachment plate having at least one recess sized to receive an inlet of a heat exchanger. The heat exchanger has a first flange disposed at the inlet that is positioned in the recess. A second flange in the attachment plate recess is crimped onto the inlet flange to couple the heat exchanger to the attachment plate. The attachment plate may also include a pair of slots that extend from the recess that are sized to receive a pair of third flanges on the heat exchanger.

Abstract: A condensing heat exchanger (100, 100a) is disclosed that includes a pair of opposing half shells (145, 145a) connected together. The half shells (145, 145a) define an inlet (111) at one end and at least one outlet (112, 113) at an opposing end of the heat exchanger. The pair of opposing half shells (145, 145a) also defines a central axis (133). Each half shell (145, 145a) includes a plurality of elongated angled beads (117, 117a, 119) that extend inwardly towards the other half shell. The elongated angled beads (117, 117a, 119) of each half shell (145, 145a) extend traversely across the central axis (133) at an angle ? with respect to the central axis (133). The beads of one half shell (145, 145a) also extend traversely across one or more beads of the other half shell.

Abstract: A compact furnace heat exchanger for a gas furnace is disclosed. The compact furnace heat exchanger may include a first pass having an inlet end, a second pass in fluid communication with the first pass through a first return bend, and a third pass having an outlet end and in fluid communication with the second pass through a second return bend. The third pass may further include a plurality of irregularities for optimizing performance of the compact furnace heat exchanger and the associated gas furnace.

Abstract: In a residential furnace having a layered insulation material on the inner walls of the heat exchanger compartment, the inner aluminum foil layer has a plurality of holes formed therein in order to allow for the outer layer to absorb the sound within the heat exchanger compartment and thereby reduce the noise emanating from the furnace. Both the density and size of the holes are optimized to maximize the sound absorption performance over the particular frequency ranges that are characteristic of the furnace.

Abstract: A media filter cabinet for a gas furnace is sized to accept a high-efficiency media filter while being easily adaptable to accept a standard size filter. A perforated duct flange on one side of the cabinet permits ease of installation since the flange can be bent at 90 or 180 degrees along the perforations, or removed, depending on the type of duct the cabinet is installed with. The cabinet is adapted to fit a standard filter by using a removable bracket and a wire to retain the standard filter within the cabinet. With the removal of a front door and a back side of the cabinet, the cabinet collapses to diminish its shipping size. In one embodiment, the cabinet is in kit form which is easily assembled.

Abstract: A heating apparatus for delivering heated air to an enclosure comprising a casing with at least two compartments separated by a panel. A burner with an arcuate profile is located within a first compartment of the casing for burning a combustible fuel-air mixture delivered thereto and producing products of combustion. A heat exchanger is located within a second compartment of the casing and has an opposed inlet and outlet. The inlet is in fluid communication with the burner through an aperture in the panel. The heat exchanger receives the products of combustion. A blower is located within the casing for directing a flow of air across the heat exchanger into the enclosure. Through the heat exchanger heat is transferred from the products of combustion to the air. An exhaust system is in fluid communication with the outlet and includes a vent for exhausting the products of combustion from the casing. The vent is contained within the casing.

Abstract: A heat exchanger manifold (44) is provided which includes a plurality of manifold inlet openings (58) including sealant means such as grommet means (62) which receive the tube outlets (40c) of the condensing section (34) of a heat exchanger (28). The heat exchanger manifold (44) is made of a corrosion-resistant material such as a polymer such as one sold under the trademark LEXAN.TM. and the grommets (62) are preferably made of a resilient, corrosionresistant polymer such as rubber, e.g., a nitrile rubber. The condensing tubes (38a, 38b, 38c) are slanted to facilitate drainage of the condensate into the heat exchanger manifold (44) and a flue gas outlet (64) and a condensate drain (49) are provided to discharge, respectively, flue gas and condensate from the heat exchanger manifold (44). The condensing tubes (38a, 38b, 38c) are connected to the primary heating section (30) of the heat exchanger (28) through swaged joints (37).

Abstract: An abatement member for inhibiting formation of oxides of nitrogen in a gas-fired furnace by controlling peak flame temperatures and residence times at the peak flame temperatures is described. The combustion system has at least one heat exchanger conduit having a flow path therethrough and at least one gas burner for burning fuel to produce a combustion flame. The abatement member has a porous refractory body portion having at least one section which is disposed transversely to the direction of flow of gases through the conduit. In one embodiment, the abatement member is a metallic screen having a serpentine shape and positioned within the fire tube. The combustion flame is directed toward and into the inlet of a fire tube and through the screen whereby the screen absorbs thermal energy from the combustion flame at a rate which limits peak flame temperatures to levels which inhibit formation of oxides of nitrogen.