A heat exchanger includes a tube expansion portion formed by expanding a heat transfer tube so that an outer peripheral surface of the heat transfer tube is pressed against an inner peripheral surface of a hole provided in a side wall portion of a case. The tube expansion portion includes first and second bulge portions positioned respectively on the inside and the outside of the side wall portion so as to sandwich the side wall portion in an axial length direction of the heat transfer tube and configured such that respective outer peripheral surfaces thereof partially bulge outward in a radial direction of the heat transfer tube, an end portion tip end of the heat transfer tube is positioned apart from the second bulge portion, and the end portion tip end and a part in the vicinity thereof are expanded so as to be included in a part of the tube expansion portion. Thus, effects such as improving the precision with which the side wall portion of the case, the heat transfer tube, and a connecting tube are fitted to each other can be achieved, and as a result, the respective parts can be brazed easily and appropriately.

A heat exchanger includes tube expansion portions provided respectively on a plurality of heat transfer tubes such that outer peripheral surfaces of the heat transfer tubes are respectively pressed against inner peripheral surfaces of a plurality of first holes provided in a side wall portion of a case, and a plurality of first concave surface portions provided in an outer surface of the tube expansion portion so that first gaps, into which brazing material of a first brazed portion advances, are formed between the outer surface of the tube expansion portion and the inner peripheral surface of the first hole. At least one of the plurality of first concave surface portions is positioned in an outside peripheral surface portion of the outer peripheral surface of the heat transfer tube. According to this configuration, the strength with which the heat transfer tubes are attached to the case can be increased while simplifying a manufacturing operation and reducing the manufacturing cost.

A heat exchanger having a first heat exchanger tube and a second heat exchanger tube is disclosed. The first heat exchanger tube can have a first leg, a second leg, and a bend section, and the bend section of the first heat exchanger tube can include three or more bends, each of the three or more bends having a corresponding bend angle that is less than or equal to approximately 90 degrees. The second heat exchanger tube can have a first leg, a second leg, and a bend section, and the bend section of the second heat exchanger tube can include three or more bends, each of the three or more bends having a corresponding bend angle that is less than or equal to approximately 90 degrees.

An electric heater to heat a flow of a fluid having a jacket block comprising a plurality of longitudinal bores to allow the through-flow of a gas phase medium. An elongate heating element extends through each of the bores and is positionally stabilised within the jacket block via a plurality of stabilising fins that project radially inward to at least partially surround the elongate heating element within each of the bores.

A heat exchanging unit exchanges heat between a fluid to be heated and exhaust gas. The heat exchanging unit includes a heat exchange portion, a header portion, and a flow changing portion. The heat exchange portion includes a heat exchange pipe in the interior of which the fluid to be heated flows. The header portion is connected to the heat exchange pipe, the header portion allowing the fluid to be heated to flow from the header portion to the heat exchange pipe or from the heat exchange pipe to the header portion. The flow changing portion changes the state of flow of the exhaust gas introduced into the heat exchange portion.

A condensation tray for condensing tankless water heaters is disclosed. The tray can include a plurality of peaks and valleys. The peaks can divert condensate runoff from a secondary heat exchanger into the valleys so as to prevent the condensate from falling on a primary heat exchanger. The tray includes gas apertures that enable combustion gases to pass through the tray and across the secondary heat exchanger. Overhangs on the peaks can prevent the condensate from draining through the gas apertures.

A heat transfer fin (1) includes a plurality of heat-transfer-tube insertion holes (10) aligned in a single stage, a downstream cut portion (3) formed so as to be recessed toward an upstream side of a gas flow passage of combustion exhaust gas, a downstream flange (13) formed on a peripheral edge of the downstream cut portion (3) so as to protrude from one surface of the heat transfer fin (1), and a plurality of first protruding pieces (4a) (4b) (4c) formed between the heat-transfer-tube insertion hole (10) and the downstream flange (13) so as to protrude alternately from both surfaces of the heat transfer fin (1).

The disclosed technology includes a fluid heating device including a frustoconical combustion chamber and a heat exchanger that can include heating tubes. The combustion chamber can have a first end and a second end that is in fluid communication with the heating tubes. The surface area of the second end of the combustion chamber can be larger than the surface area of the first end of the combustion chamber.

Swimming pool or spa gas heaters, cabinets, water header manifolds, and heat exchangers include: gas heaters having an air gap between a cabinet and combustion chamber to reduce heat transfer to sides of the cabinet; gas heaters having a user interface that is repositionable on a top panel; gas heater cabinets including a removable top panel that can be hung on a side panel; gas heaters having a built-in dual junction box; gas heaters having a top-accessible igniter and burner that are interlocked to maintain positioning thereof; adaptable water manifolds including connectable inlet and outlet fittings that adjust effective inlet and outlet positions; heat exchangers having a plurality of tube-and-fin subassemblies arranged in a semi-circular configuration; and water manifolds including internal cartridges that divide the water manifold into a plurality of chambers for improved circulation through a heat exchanger.

Swimming pool or spa gas heaters, cabinets, water header manifolds, and heat exchangers include: gas heaters having an air gap between a cabinet and combustion chamber to reduce heat transfer to sides of the cabinet; gas heaters having a user interface that is repositionable on a top panel; gas heater cabinets including a removable top panel that can be hung on a side panel; gas heaters having a built-in dual junction box; gas heaters having a top-accessible igniter and burner that are interlocked to maintain positioning thereof; adaptable water manifolds including connectable inlet and outlet fittings that adjust effective inlet and outlet positions; heat exchangers having a plurality of tube-and-fin subassemblies arranged in a semi-circular configuration; and water manifolds including internal cartridges that divide the water manifold into a plurality of chambers for improved circulation through a heat exchanger are disclosed.