Abstract: A CEHB, a furnace and a method of constructing a furnace are disclosed. In one embodiment, the CEHB includes: (1) a fixed orifice configured to regulate air flow through a heat exchanger of the furnace, wherein a combustion air inducer induces the air flow and (2) a negative pressure channel including a negative channel supply port that communicates with an inlet of the combustion air inducer, a negative pressure port configured to connect to a negative input port of a pressure switch and bleed ports configured to reduce a pressure received through the negative channel supply port at the inlet to a targeted range at the negative pressure port, the pressure switch configured to monitor a combustion pressure through the heat exchanger.

Abstract: A clamshell heat exchanger for use in a gas-fired direct combustion furnace. The exchanger comprises a first clamshell half and a second clamshell half that when joined with the first clamshell half forms a passageway having an inlet and an outlet. The passageway includes a U-bend located between the inlet and the outlet, wherein the U-bend includes a re-entrant sectional profile.

Abstract: The disclosure provides a controller for a multistage gas furnace, a multistage gas furnace and computer readable medium for performing a method to operate a furnace. In one embodiment, the controller includes: (1) an interface configured to receive a heating call and (2) a corrosion reducer configured to ignite the gas furnace at a high fire operation based on if an indoor circulating fan of the gas furnace is active.

Abstract: A condensation management system, a furnace having the condensation management system and a cold end header box employable in the condensation management system are disclosed herein. In one embodiment, the condensation management system includes: (1) a first drain hose positioned to drain flue condensation from a flue pipe of the furnace, (2) a second drain hose positioned to drain the flue condensation from the flue pipe and (3) a condensation collector box configured to collect both the flue condensation and combustion condensation from a heat exchanger of the furnace, the condensation collector box including at least one drain for draining both the flue condensation and the combustion condensation therefrom.

Abstract: A condensation trap comprising an inlet chamber, a vent chamber and an outlet chamber. The inlet chamber is configured to receive condensate fluid through an external opening therein. The vent chamber is in fluid communication with the inlet chamber via a first passageway that includes an internal opening of the inlet chamber. The internal opening is located substantially at an opposite end of the vent chamber as the external opening. The outlet chamber is in fluid communication with the vent chamber via a second passageway that includes an internal opening in a sidewall of the vent chamber and an interior opening in an end of the outlet chamber. The outlet chamber is configured to transmit the condensate fluid through an exterior opening located at an opposite end of the outlet chamber. A vent volume portion is greater than a total volume of an internal space of the inlet chamber.

Abstract: A CEHB, a furnace and a method of constructing a furnace are disclosed. In one embodiment, the CEHB includes: (1) a fixed orifice configured to regulate air flow through a heat exchanger of the furnace, wherein a combustion air inducer induces the air flow and (2) a negative pressure channel including a negative channel supply port that communicates with an inlet of the combustion air inducer, a negative pressure port configured to connect to a negative input port of a pressure switch and bleed ports configured to reduce a pressure received through the negative channel supply port at the inlet to a targeted range at the negative pressure port, the pressure switch configured to monitor a combustion pressure through the heat exchanger.

Abstract: A header box, a furnace and a blocked condensation protection system are disclosed herein. In one embodiment, the header box includes: (1) a first channel having a first channel supply port positioned to be in fluid communication with an inlet of a combustion air blower and a first pressure port couplable to a first input of a pressure sensing device, the combustion air blower and the pressure sensing device associated with the cold end header box and (2) a second channel having a second channel supply port positioned to be in fluid communication with the inlet of the combustion air blower, a second pressure port couplable to a second input of the pressure sensing device and a pressure reference inlet, the second channel in fluid communication with the first channel and configured to have about a same pressure as the first channel when the pressure reference inlet is blocked.

Abstract: A clamshell heat exchanger includes a first clamshell half and a second clamshell half. When joined, the first and second clamshell halves form a passageway having an inlet and an outlet. The passageway has a height and a depth. A ratio of the height to the depth is about 0.5 or less. The heat exchanger has an efficiency of at least about 70%.

Abstract: An HVAC burner box includes a burner bank, a manifold and an air director located within an enclosure. The burner bank is oriented such that an outlet end of the burner bank is directed toward a first end of the enclosure. The manifold is located within the enclosure and adjacent an inlet end of the burner bank. The air director has a diffuser that is coupled to a side of the enclosure. The diffuser includes a plurality of openings located therethrough. The diffuser is configured to direct a first portion of a received airstream through the opening and toward the burner bank. The diffuser is further configured to send a second portion of the received airstream toward the manifold.

Abstract: An alternative-fuel gas orifice, a gas furnace configured to employ the same and a method of designing a gas orifice. In one embodiment, the gas orifice includes: (1) a body having an aperture extending therethrough and including: (1a) a metering neck having a cross-sectional area such that a given flow rate of a gas is established when the gas is delivered to the gas orifice at a given alternative-fuel delivery pressure and (1b) a diffuser having a cross-sectional area larger than the cross-sectional area of the metering neck and a length such that the gas achieves a substantially laminar flow before exiting the diffuser.

Abstract: A furnace unit that comprises a burner assembly having at least one burner located therein and a heat exchanger having at least one continuous combustion tube. One end of the combustion tube has a first opening that is coupled to the burner assembly. The combustion tube has at least three zones. A first surface of the first zone has a first non-straight angle with a second surface of the second zone. The second surface has a second non-straight angle with a third surface of the third zone. The first zone is nearest of the three zones to the burner assembly and the second zone is in-between the first zone and the third zone. The first, second and third zones are within a flame length configured to be emitted from the burner.