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.

Provided is a heating blower, comprising an air duct, a motor and a wind wheel arranged in the air duct, and a heating device arranged at a first air outlet of the air duct; the wind wheel is fixed to a rotating shaft of the motor; the heating device comprises a housing, an electric heater and a moving assembly; the housing is sleeved on the first air outlet, forming an inner chamber, which comprises a first area facing directly to the first air outlet and a second area not facing directly to the first air outlet; the electric heater is arranged on the moving assembly, and moves between the first area and the second area along with the moving assembly, so that an airflow blown from the first air outlet switches between a state of passing the electric heater and a state of not passing the electric heater, and is blown out from a second air outlet provided at the housing.

Provided is a heating blower, comprising an air duct, a motor and a wind wheel arranged in the air duct, and a heating device arranged at a first air outlet of the air duct; the wind wheel is fixed to a rotating shaft of the motor; the heating device comprises a housing, an electric heater and a moving assembly; the housing is sleeved on the first air outlet, forming an inner chamber, which comprises a first area facing directly to the first air outlet and a second area not facing directly to the first air outlet; the electric heater is arranged on the moving assembly, and moves between the first area and the second area along with the moving assembly, so that an airflow blown from the first air outlet switches between a state of passing the electric heater and a state of not passing the electric heater, and is blown out from a second air outlet provided at the housing.

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 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.

Described is a liquid heater having a housing, in which a flow channel runs from an inlet to an outlet, a heating resistor arranged within the housing for heating liquid flowing through the flow channel, control electronics which are arranged in an interior space of the housing, the interior space being sealed off from the flow channel, and a plug connector attached to the housing. Provided according to this disclosure, the plug connector has a vent duct which is closed by a membrane and which leads to the interior space sealed against the ingress of liquid, in which interior space the control electronics are arranged.

Described is a liquid heater having a housing, in which a flow channel runs from an inlet to an outlet, a heating resistor arranged within the housing for heating liquid flowing through the flow channel, control electronics which are arranged in an interior space of the housing, the interior space being sealed off from the flow channel, and a plug connector attached to the housing. Provided according to this disclosure, the plug connector has a vent duct which is closed by a membrane and which leads to the interior space sealed against the ingress of liquid, in which interior space the control electronics are arranged.

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.

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.