A heat exchanger includes a core portion, a pair of header tanks, and an elastically-deformable sealing member. The header tanks are arranged on both end sides of the core portion. The header tank includes a core plate and a resin tank body, which define a tank space. The sealing member is disposed at an end part of the tank body located adjacent to the core plate. The sealing member has a loop shape to enclose the tank space when viewed from the core portion and is formed integrally with the end part of the tank body. The end part of the tank body includes a protrusion portion at least one of inward and outward of the sealing member. The protrusion portion encloses the tank space when viewed from the core portion and projects from the end part of the tank body toward the core plate.

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.

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.

A method for constructing a heat exchanger having a pair of headers and a plurality of tubes extending between and fluidly connecting the headers is described. For each header, a pair of body elements is provided each formed of brazing clad material. A tubular assembly is formed of brazing clad material for each tube. The tubular assembly, for each tube, is fitted into apertures. The body elements and the tubular assemblies are brazed together to form the heat exchanger.

A manifold assembly includes a first channel, a second channel and a manifold. The first channel has a first flow profile and a manifold end with a first cross-sectional geometry. The second channel has a second flow profile and a manifold end with a second cross-sectional geometry, which may be different than the first cross-sectional geometry. A first channel port of the manifold is configured to mate with the manifold end of the first channel. A second channel port of the manifold is configured to mate with the manifold end of the second channel.

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.