A method of operating a gas heater for water including the steps of restricting a water flow to the gas heater; determining a first rate of a first gas heating for the restricted water flow; adjusting the gas heating to the restricted water flow; repeating the previous steps until a heated water has a temperature above a temperature threshold; removing the restriction to the water flow to increase the water flow; and determining a second rate of a second gas heating for the increased water flow.

An aspect of the present disclosure provides a flow channel cap plate that constitutes a combustion chamber assembly including a combustion chamber and a plurality of insulating pipelines disposed on left/right side surfaces of the combustion chamber, the flow channel cap plate forming an insulating flow channel by covering the front surface of the combustion chamber, the flow channel cap plate including an inlet part including an inlet, and an inlet flow channel cap covering the front surface of the combustion chamber, an inlet space part is formed by covering the front surface of the combustion chamber with the inlet flow channel cap, the inlet is an entrance of the insulating flow channel, the plurality of insulating pipelines include a plurality of inlet insulating pipelines, and the inlet space part is a space that communicates the inlet with the plurality of inlet insulating pipelines.

A modular manifold for a tankless water heater includes a first cavity member having a first opening, a second opening, and a base wall; a second cavity member coupled to the first cavity member, the second cavity member having a first opening, a second opening, and a base wall; a first cover plate coupled to either the first cavity member or the second cavity member; and a second cover plate coupled to either the first cavity member or the second cavity member, wherein two openings in the first and second openings are covered by the first and second cover plates, respectively, and wherein the base walls of the first and second cavity members, the first and second cover plates, and the two openings in the first and second openings not covered by the first and second cover plates define a fluid flow path in the modular manifold.

A modular manifold for a tankless water heater includes a first cavity member having a first opening, a second opening, and a base wall; a second cavity member coupled to the first cavity member, the second cavity member having a first opening, a second opening, and a base wall; a first cover plate coupled to either the first cavity member or the second cavity member; and a second cover plate coupled to either the first cavity member or the second cavity member, wherein two openings in the first and second openings are covered by the first and second cover plates, respectively, and wherein the base walls of the first and second cavity members, the first and second cover plates, and the two openings in the first and second openings not covered by the first and second cover plates define a fluid flow path in the modular manifold.

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.

Embodiments include various water heaters. In one example, a water heater includes a burner, an exhaust vent, a corrugated baffle having a first slit having a first length and a second slit having a second length that is less than the first length, and a heat exchanger. The heat exchanger includes a first set of heat exchanger tubes arranged in a first row, and a second set of heat exchanger tubes arranged in a second row, the second set of heat exchanger tubes having a third tube having a first angled surface and a second angled surface, where the first angled surface and the second angled surface together form a fin. The third tube can be arranged such that the fin is disposed at least partially between the first curved outer surface and the second curved outer surface.

A gas manifold allows each distribution chamber to be fed with fuel gas at an appropriate flow rate irrespective of an increase in the number of distribution chambers included in the gas manifold. A gas manifold distributes fuel gas flowing in through an inlet to a plurality of distribution chambers through a main channel. The main channel includes a flow guide that guides the fuel gas toward a maximum distribution chamber and reduces the fuel gas flowing into other distribution chambers. This allows fuel gas at a sufficient flow rate to be fed more easily to the maximum distribution chamber than to the other distribution chambers for a larger number of distribution chambers included in the gas manifold, allowing the plurality of distribution chambers to be fed with fuel gas at appropriate flow rates.

The present invention provides a method of operating a gas heater for water including the steps of: restricting a water flow to the gas heater; determining a first rate of a first gas heating for the restricted water flow; adjusting the gas heating to the restricted water flow; repeating the previous steps until a heated water has a temperature above a temperature threshold; removing the restriction to the water flow to increase the water flow; and determining a second rate of a second gas heating for the increased water flow. The present invention also provides a gas water heater which utilises such a method.

The present invention provides an electric boiler having a heating element surrounded by a thermally conductive inner container to define an inner passage about the heating element, the inner container having an inlet 13, 14 and an outlet for a flow of water and is arranged such as to cause water received at the inner container inlet to flow along the inner passage in close proximity to a surface of the heating element, the boiler further comprising an outer container in which the inner container is substantially located, the outer container defining an outer passage about at least part of the inner container, the outer container having an outlet into the inner container wherein the outer container is arranged such as to cause water to flow along the outer passage in close proximity to a surface of the inner container, such that water received in the boiler makes at least a double pass through the boiler to increase the potential heat transfer to the water.

In a water heater provided with an inlet pipe a downstream end of which is connected with an upstream end of a water heating channel of a heat exchanger for producing hot water, an outlet pipe an upstream end of which is connected with a downstream end of the water heating channel, and a bypass pipe branching at a part of the inlet pipe, which is positioned at an upstream-end part away from an upstream end, and is connected with a part of the outlet pipe, which is positioned at a more downstream part than at an upstream end, a connecting part of the bypass pipe with the outlet pipe and another connecting part of an inlet pipe and the upstream end of the water heating channel are arranged at a same height in a setting state of the water heater.