A water heater can include a baffle and a slab heat exchanger with at least two rows of heat exchanger tubes, each row comprising a plurality of heat exchanger tubes. At least one of the heat exchanger tubes comprises a tube and a plurality of fins on the exterior of the tube circumscribing the tube, wherein the outer edge of each fin of the plurality of fins is bent at least at the same three areas of each fin such that the bends form at least three flat or concave areas running along the length of the heat exchanger tube.

A heating and hot water supply system, including: a combustion unit combusting a fuel to generate a combustion gas; a heat exchange unit heating a heat medium and hot water according to heat exchange with the combustion gas; an exhaust unit that exhausting the combustion gas after heat exchange The heat exchange unit includes a plate type heat exchanger by laminating vertically-upright rectangular plates with gaps, and is configured to heat the heat medium by causing the combustion gas and the heat medium to alternately flow through the gaps An inlet for the heat medium is provided at lower corner of the plate type heat exchanger, a discharge opening for the heat medium is provided at upper corner farthest from the inlet, and a hot water passage through which hot water flows in the plate type heat exchanger is provided at upper corner above the inlet.

An extreme condensing boiler includes cold and hot water headers, burner, and multi-tubing heat exchanger, so that cold water absorbs heat from exhaust gas of the burner being heated to medium-hot, which absorbs heat generated by the burner being heated to hot water through absorbing heat from both sides of tube portion of the multi-tubing heat exchanger, and so that the hot water is delivered to the hot water header, and a combustion air heat exchanger is provided around the multi-tubing heat exchanger. The condensing boiler uses dual/triple tubes for fire and water tubes, increasing efficiency by absorbing heat from both sides. The fire tube is surrounded by the cold water tube so as to minimize exhaust gas temperature and maximize condensing by absorbing waste heat. The condensing boiler realizes a direct fire boiler through the fire and water tubes, and an energy-saving tankless boiler including headers and tubes only.

A heat exchanger includes a plurality of serpentine or U-shaped first heat transfer tubes disposed in a case and formed by connecting a plurality of straight tube body portions, which are arranged at intervals in an up-down height direction so as to extend in a horizontal direction, in series via a first connecting tube body portion, upper side and lower side header portions connected to respective end portions of the plurality of first heat transfer tubes, and a second heat transfer tube disposed in the case so that upper side and lower side end portions thereof are connected respectively to the upper side and lower side header portions and configured such that an intermediate region, which excludes at least the respective end portions and a region of an uppermost portion that is adjacent to the upper side end portion, is constituted by tube body portions that are tilted over the entire length thereof so as to gradually decrease in height from one end side toward another end side of the intermediate region. As a result, a malfunction in which a hot water supply operation becomes difficult due to freezing of the heat transfer tubes can be prevented appropriately.

A fired heater has two cells segregated by an insulative wall. A first plurality of burners are located in the first cell and a second plurality of burners are located in the second cell. A radiant tube extends from the first cell to the second cell for carrying a fluid material through the heater to heat the fluid material. The flow of fuel to the burners in either the first cell or the second cell can be terminated to accommodate lower heater duty when demand is lower.

The present disclosure provides a gas distribution assembly and a water-heating device including the same. The gas distribution assembly for distributing a gas to a plurality of burners includes a manifold unit detachably assembled to an outer surface of a combustion chamber in which the plurality of burners are received, the manifold unit including a plurality of gas nozzles that eject the gas to gas inlets of the burners through an opening of the combustion chamber, and a gas supply unit that is assembled to the manifold unit so as to be separable and that supplies, to the manifold unit, the gas introduced into the gas supply unit. The manifold unit is separated from the combustion chamber and the gas supply unit as needed for replacement.

A heating apparatus is disclosed. The heating apparatus comprises a PTC heating element, a first electrode, a second electrode, a first protection layer, a second protection layer, a first interlayer, and a second interlayer. A hardness of the first protection layer is greater than that of the first interlayer. A hardness of the second protection layer is greater than that of the second interlayer.

A plate heat exchanger includes a plurality of plates stacked so that a liquid flow passage is formed on the inside thereof, and a gas flow passage through which heating gas passes, the gas flow passage being formed between the plurality of plates and including a gas inflow opening portion and a gas outflow opening portion positioned on an opposite side to the gas inflow opening portion, wherein the gas outflow opening portion has a smaller opening area than the gas inflow opening portion. Thus, when the heating gas passes through the gas flow passage, even if the volumetric flow thereof decreases due to a reduction in temperature or condensation, a reduction in the flow velocity of the heating gas can be suppressed. Hence, a reduction in a heat transfer coefficient can be suppressed, leading to an improvement in heat transfer efficiency, and as a result, reductions in overall size, weight, and manufacturing cost can be achieved appropriately.

A transfer 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, where the at least one wall further has a first end and a second end. The first end can be configured to couple to a terminus of a heat exchanger of the thermal transfer device. The second end can be configured to couple to a collector box of the thermal transfer device. At least a portion of the at least one wall can be disposed in a vestibule of the thermal transfer device. The cavity can be configured to simultaneously receive a first fluid that flows from the first end to the second end and a second fluid that flows from the second end to the first end.

The present disclosure is directed to a tankless water heater and systems and methods of using the same. The tankless water heater embodiments of the present disclosure can be configured to have a plurality of independently operable heat exchangers that can be used individually or collectively, in any combination, to heat water based on the level of demand for hot water. Embodiments can be configured for randomly selecting which heat exchangers are used to heat the incoming water. Embodiments of the present disclosure can also be configured to flow water through heat exchangers that are not being used to heat water and direct such water to a recirculation loop.