Abstract: A heat exchanger includes a case, a first and second heat exchanger disposed inside the case, a partition member disposed inside the case, and a duct. The case has a first side wall and a second side wall spaced apart from and facing each other in a first direction, a third side wall and a fourth side wall spaced apart from and facing each other in a second direction orthogonal to the first direction, and a bottom wall. A gas outlet communicating with an interior of the case is formed in the first side wall. The first heat exchanger is farther from the bottom wall than the second heat exchanger in a third direction orthogonal to the first and second directions. The second heat exchanger includes meandering heat transfer tubes meandering within a plane orthogonal to the first direction and overlapping along the first direction.

Abstract: A premixing device includes: a gas flow path for allowing air to flow; a gas outlet that allows fuel gas to flow out into the gas flow path by utilizing a negative pressure; and a flapper disposed in the gas flow path. The premixing device further includes an operation regulating part for the flapper which allows the opening degree of the flapper to change according to the air flow rate in a range below a predetermined upper limit position while preventing the flapper from rotating in an opening direction beyond the upper limit position. The operation regulating part is capable of selectively switching and setting one of a first upper limit position for normal combustion and a second upper limit position for fuel ignition. The opening degree of the flapper at the second upper limit position is smaller than that at the first upper limit position.

Abstract: A water heating apparatus is provided. The water heating apparatus includes a pump and is configured to be able to set a hot-water circulation route to circulate hot water discharged from a heat exchanger to be re-entered into the heat exchanger by operation of the pump. When a state of a hot-water supply operation in which a burner drives combustion is changed to an end state, hot water in the heat exchanger is circulated in the hot-water circulation route to suppress deposition of scale.

Abstract: 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.

Abstract: 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.

Abstract: A shaft body (12) is rotatable around an axial line (C-C). A first valve element (13a) is located between a first opening (11a) and a second opening (11b) and it has a first notch (13a1). A second valve element (13b) is located between first opening (11a) and a third opening (11c) and it has a second notch (13b1). By rotating first and second valve elements (13a, 13b) around the axial line (C-C) as a center (O), an operation for opening and closing first and second notches (13a1, 13b1) can be performed.

Abstract: A combustion apparatus (1) with a burner port assembly (3) comprises an elongated first array of main burner ports (53) for jetting and burning a fuel gas mixture of a concentration to make main flames. The combustion apparatus (1) comprises at least one second arrays of auxiliary burner ports (63) for jetting and burning a further fuel gas mixture of a different concentration to make auxiliary flames, wherein the second arrays of said auxiliary burner ports (63) extend along the first array of said main burner ports (53). The burner port assembly (3) is constructed using inner and outer wall segments (52) together with outermost wall segments (52a,52f) or bands (58). One of the bands (58) faces the corresponding one of said outermost segments (52a,52f) so as to define between them collateral burner ports (61a,61b).

Abstract: A combustion apparatus (1) with a burner port assembly (3) comprises an elongated first array of main burner ports (53) for jetting and burning a fuel gas mixture of a concentration to make main flames. The combustion apparatus (1) comprises at least one second arrays of auxiliary burner ports (63) for jetting and burning a further fuel gas mixture of a different concentration to make auxiliary flames, wherein the second arrays of said auxiliary burner ports (63) extend along the first array of said main burner ports (53). The burner port assembly (3) is constructed using inner and outer wall segments (52) together with outermost wall segments (52a,52f) or bands (58). One of the bands (58) faces the corresponding one of said outermost segments (52a,52f) so as to define between them collateral burner ports (61a,61b).