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: A control system to control the operation of a furnace (10) having a fuel control unit (26) to supply fuel to a burner (24) includes a limit switch (48) within furnace (10) to detect an overheated condition. The limit switch (48) opens when a reference temperature is reached, shutting down the furnace (10). A logic unit (40) senses the state of the limit switch (48) and measures the shutdown period, and notes whether the shutdown period exceeds a predetermined interval. The logic unit (40) opens a lockout switch (38') that controls the fuel control unit (26) if the furnace is subject to a number of consecutive prolonged shutdowns that exceeds a predetermined limit.

Abstract: A single forced air furnace (10) may be installed in any of an upflow, downflow, or horizontal airflow orientation, with discharge of flue gases either opposite to or concurrent with the primary airflow path. The combination of design features which provides this versatility includes the following features: an inducer assembly (24) for withdrawing flue gas from the furnace heat exchanger (20), which inducer assembly (24) may be positioned to direct the discharge of flue gas in a selected one of a plurality of directions; an optional internal flue duct (64) for directing the flue gas through the furnace vestibule chamber then through the furnace housing (12); and the fact that the furnace housing (12) is dimensioned and configured so that the furnace may be supported on any one of four different sides (O, I, S.sub.1, S.sub.2) of the furnace housing (12).

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.

Abstract: A forced air furnace (11) has a heat exchanger (35) with one or more tube pack assemblies (10). Each tube pack assembly (10) has a burner (21) situated to fire into a primary fire tube (30) which is mechanically connected through a transition cap (36) to a plurality of secondary tubes (37, 38, 39, 41) returning combustion products from the primary fire tube (30) to a collection manifold (24) at the intake end of a draft inducer assembly (23) for discharge of the combustion products to a flue. In the preferred embodiment, the transition cap (36) is connected to the primary fire tube (30) and to the secondary tubes (37, 38, 39, 41) by a mechanical interlock.