A heat exchanger includes a tube expansion portion provided on a heat transfer tube such that an outer peripheral surface of the heat transfer tube is pressed against an inner peripheral surface of a first hole provided in a side wall portion of a case, and a first concave surface portion that is provided in a part of an outer surface of the tube expansion portion and forms a first gap, into which brazing material of a first brazed portion advances, between the outer surface of the tube expansion portion and the inner peripheral surface of the first hole. Thus, the attachment strength of the heat transfer tube can be improved by means of a simple configuration.

The heat exchange device (200) includes a primary heat exchanger (10), a secondary heat exchanger (20), and a connecting pipe (60). The connecting pipe connects the primary heat exchanger and the secondary heat exchanger. The primary heat exchanger (10) includes a primary heat exchange part (11), a shell plate (12) surrounding the primary heat exchange part, and a body pipe part (13) for cooling the shell plate. The body pipe part (13) is disposed closer to a burner than the primary heat exchange part (11) and is connected to the connecting pipe (60). The primary heat exchange part (11) includes a first heat transfer tube part (111) connected to the body pipe part (13), and a second heat transfer tube part (112) connected to the first heat transfer tube part and disposed on a side opposite to the body pipe part with respect to the first heat transfer tube part.

The heat exchange device (200) includes a primary heat exchanger (10), a secondary heat exchanger (20), and a connecting pipe (60). The connecting pipe connects the primary heat exchanger and the secondary heat exchanger. The primary heat exchanger (10) includes a primary heat exchange part (11), a shell plate (12) surrounding the primary heat exchange part, and a body pipe part (13) for cooling the shell plate. The body pipe part (13) is disposed closer to a burner than the primary heat exchange part (11) and is connected to the connecting pipe (60). The primary heat exchange part (11) includes a first heat transfer tube part (111) connected to the body pipe part (13), and a second heat transfer tube part (112) connected to the first heat transfer tube part and disposed on a side opposite to the body pipe part with respect to the first heat transfer tube part.

According to the present invention, a heat exchanger comprises a fin having a plurality of through holes. The plurality of through holes include mutually adjacent first and second through holes disposed on a side closest to a heating gas's inlet side. The fin has a slit located between the first through hole and the second through hole and cut into the fin from an edge thereof located on the heating gas's inlet side to a side farther from the heating gas's inlet side than a reference line connecting a center of the first through hole and a center of the second through hole. Furthermore, the fin has at least one opening between the slit and the first and second through holes. The opening includes a first opening having a portion located on the side farther from the heating gas's inlet side than the reference line.

According to the present invention, a heat exchanger comprises a fin having a plurality of through holes. The plurality of through holes include mutually adjacent first and second through holes disposed on a side closest to a heating gas's inlet side. The fin has a slit located between the first through hole and the second through hole and cut into the fin from an edge thereof located on the heating gas's inlet side to a side farther from the heating gas's inlet side than a reference line connecting a center of the first through hole and a center of the second through hole. Furthermore, the fin has at least one opening between the slit and the first and second through holes. The opening includes a first opening having a portion located on the side farther from the heating gas's inlet side than the reference line.

Provided are a heat exchanger capable of cooling a shell plate and having good assemblability and a hot water apparatus having the same. A primary heat exchanger includes a heat exchanging portion, a shell plate, and a shell pipe portion. The shell plate surrounds the heat exchanging portion. The shell pipe portion is for cooling the shell plate. The shell plate includes a front surface portion and a main body portion. The main body portion is installed on the front surface portion and is formed by bending one sheet of plate into a U shape. The shell pipe portion is bent in a U shape along an inner surface of the main body portion and installed on the inner surface.

A burn box includes a font, a rear, a first and a second side, a lower, and an upper interior surface, as well as a first push member, a first coupler, and a first torque member. The first push member includes a first end, a second end, and a first coupler portion. The first coupler pivotally couples the first coupler portion to the first interior surface. The second end is vertically intermediate the first end and the lower interior surface. The first torque member provides a first torque to the first push member. When the first torque is provided to the first push member, the first push member rotates about a first rotational axis. The first rotational axis is through the first coupler portion of the first push member. The first rotational axis is parallel to the longitudinal axis. The second end rotates toward the second side interior surface.

A burn box includes a font, a rear, a first and a second side, a lower, and an upper interior surface, as well as a first push member, a first coupler, and a first torque member. The first push member includes a first end, a second end, and a first coupler portion. The first coupler pivotally couples the first coupler portion to the first interior surface. The second end is vertically intermediate the first end and the lower interior surface. The first torque member provides a first torque to the first push member. When the first torque is provided to the first push member, the first push member rotates about a first rotational axis. The first rotational axis is through the first coupler portion of the first push member. The first rotational axis is parallel to the longitudinal axis. The second end rotates toward the second side interior surface.

A header of a heat exchanger including a first wall connected with a plurality of heat transfer tubes of the heat exchanger, a second wall facing the first wall with an interval therebetween, and a circumferential wall connecting outer circumferential edges of the first and the second walls in such a manner that an area between the first and the second walls constitutes a chamber for inflow of fluid, the chamber communicating with each of the heat transfer tube. At least one of the first and the second walls is configured to curve in such a manner that a central area of the wall is positioned close to an inside of the chamber than an outer circumferential area of the wall. The thickness of the header is reduced and enough strength of the header is obtained, thereby preferably enduring repeating water hammer.

A header of a heat exchanger including a first wall connected with a plurality of heat transfer tubes of the heat exchanger, a second wall facing the first wall with an interval therebetween, and a circumferential wall connecting outer circumferential edges of the first and the second walls in such a manner that an area between the first and the second walls constitutes a chamber for inflow of fluid, the chamber communicating with each of the heat transfer tube. At least one of the first and the second walls is configured to curve in such a manner that a central area of the wall is positioned close to an inside of the chamber than an outer circumferential area of the wall. The thickness of the header is reduced and enough strength of the header is obtained, thereby preferably enduring repeating water hammer.