The present subject matter includes a heat exchange part having heating medium channels, through which heating medium flows, and combustion gas channels, through which combustion gas burned in a burner flows, adjacently disposed in alternation in the spaces between the plurality of plates, the heat exchange part being provided in multiple numbers in a stacked structure, and having a heating medium distribution part for narrowing the channel at points where the flow direction of the heating medium is switched in adjacently located heating medium channels.

A baffle for a thermal transfer device can include a body having a multiple first apertures that traverse therethrough, where each first aperture has a first outer perimeter that includes a first base shape and at least one first protrusion extending from the first base shape. Each of the first apertures is configured to receive a tube. The first base shape of each first aperture has a first shape and a first size that is configured to be substantially the same as the first shape and the first size of an end of a tube.

A tube for a thermal transfer device can include at least one wall having an inner surface and an outer surface, where the inner surface forms a cavity. The inner surface can be non-cylindrical. The cavity can be configured to receive a fluid that flows continuously along a length of the at least one wall.

A baffle for a thermal transfer device can include a body having a multiple first apertures that traverse therethrough, where each first aperture has a first outer perimeter that includes a first base shape and at least one first protrusion extending from the first base shape. Each of the first apertures is configured to receive a tube. The first base shape of each first aperture has a first shape and a first size that is configured to be substantially the same as the first shape and the first size of an end of a tube.

A heat exchanger unit according to the present invention includes a sensible heat exchanger including a sensible heat exchange pipe disposed in a sensible heat exchange area for heating water used for heating by receiving sensible heat generated by a combustion reaction, wherein the sensible heat exchange pipe receives the water used for heating and flows same through the interior, and a sensible heat fin disposed in the sensible heat exchange area. The sensible heat fin is formed in a plate shape across the sensible heat exchange pipe and penetrated by the sensible heat exchange pipe; and a latent heat exchanger positioned downstream from the sensible heat exchange area on the basis of a reference direction, which is a flow direction of combustion gas generated during the combustion reaction, the latent heat exchanger including a latent heat exchange pipe disposed in a latent heat exchange area.

A water heater according to the present invention includes: a heating unit that includes a burner provided to cause a combustion reaction from air and fuel, and that is provided to generate heated water by using heat generated by the combustion reaction; and a humidifier unit that generates water steam by evaporating water using a combustion gas generated by the combustion reaction and discharged from the heating unit, and provides the water steam together with the air to the burner.

A heat exchanger includes a case, fins, and heat transfer tubes. Combustion exhaust gas passes downward in the case. The fins are disposed at a lower portion of the case and arranged in the first direction. Each of the fins includes a first end and a second end that is an opposite end from the first end in a second direction intersecting the first direction. Each of the fins includes through holes in which the heat transfer tubes are inserted. Each of the fins includes heat receiving portions arranged in the second direction and connecting portion connecting the heat receiving portions. The heat receiving portions include a first heat receiving portion disposed at the first end. The first heat receiving portion includes a first recessed portion recessed from an outer edge of an upper part of the first heat receiving portion.

A diffuser plate for a thermal transfer device can include a body having a number of first apertures and a second aperture that traverse therethrough, where the first apertures are asymmetrically arranged with respect to the second aperture. The first apertures can have a first shape and a first size, and where the first apertures are configured to receive a plurality of tubes. The second aperture has a second size, where the second size is larger than the first size.

A plate for a heat exchange arrangement for the exchange of heat between a first and a second medium. The plate has a first heat transferring surface in contact with the first medium and a second heat transferring surface in contact with the second medium. The plate includes an inlet porthole for the first medium; an inlet porthole for the second medium, and an outlet porthole for the first medium. The first heat transferring surface includes a protrusion forming at least one ridge arranged to divide the heat transfer surface into at least a first region in direct thermal contact with the inlet porthole for the second medium, and a second region not in direct thermal contact with the inlet porthole for the second medium. The second region substantially surrounds the first region. The inlet porthole for the first medium is arranged in the first region, while the outlet porthole for the first medium is arranged in the second region. Moreover, the at least one ridge forms at least one elongated transfer channel arranged to convey the first medium from the first region to the second region.

Water heaters, baffles for water heaters, and methods for manufacturing such baffles are disclosed, One baffle includes a core, an outer wall, and a plurality of fins. The outer wall surrounds the core and defines at least one flow path between the outer wall and the core. The plurality of fins extend from the outer wall toward the core. Each of the plurality of fins has a serpentine shape. One method for manufacturing a baffle includes extruding at least one portion of the baffle in one piece, the at least one portion of the baffle having an at least partially cylindrical outer wall u and a plurality of fins extending inward from the outer wall, each of the plurality of fins having a serpentine shape. One water heating system includes a burner, a vent, at least one flue tube, and at least one baffle as described above.