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.

A heating apparatus can have a sealed combustion chamber, a burner, and various air channels to direct air into the sealed combustion chamber and to provide heated air to the desired area or environment such as an interior room. A channel can direct a flow of air along a face of the sealed combustion chamber to cool the face. The channel can be within or outside of the sealed combustion chamber. Alternatively, or in addition, the heating apparatus can be capable of operating as a direct vent device or as a vent free device.

Disclosed are a gas furnace and an air conditioner having the same. The gas furnace includes: a burner for burning fuel; a manifold providing the fuel to an entry of the burner; a heat exchanger spaced apart from an exit of the burner and providing a passage for combustion gas generated by the burner; an inducer for causing a fluid to flow through the burner and the heat exchanger; a blower for causing a flow of air passing around the heat exchanger; and an air shutter positioned between the manifold and the entry of the burner. The air shutter includes: a housing having an inner space that communicates with the manifold and the entry of the burner; and a primary hole formed to penetrate the housing and able to be opened and closed.