NORITZ CORPORATION

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 heat exchanger includes a tube expansion portion provided on a heat transfer tube such that an outer peripheral surface of the heat transfer tube is pressed against an inner peripheral surface of a first hole provided in a side wall portion of a case, and a first concave surface portion that is provided in a part of an outer surface of the tube expansion portion and forms a first gap, into which brazing material of a first brazed portion advances, between the outer surface of the tube expansion portion and the inner peripheral surface of the first hole. Thus, the attachment strength of the heat transfer tube can be improved by means of a simple configuration.

A heat exchanger includes a case into which heating gas is supplied, a heat transfer pipe accommodated in the case, and first and second header sections, each of which has a chamber formed using a protruding part provided in the sidewall section, and to which the heat transfer pipe is connected such that a fluid to be heated enters and exit the chamber. The sidewall section has a configuration in which an inner plate and an outer plate overlap each other, the protruding part of the first header section is provided on the inner plate and protrudes toward an inside of the case, and the protruding part of the second header section is provided on the outer plate and protrudes toward an outside of the case.

A heat exchanger includes fins and a plurality of pairs of cut-and-raised parts. Each pair of the cut-and-raised parts are positioned on both left and right sides in a width direction on a downstream side in a heating gas flowing direction around an outer circumference surface of each of upstream pipe body parts and face a downstream part on the outer circumference surface with a first gap therebetween. A width between upstream end parts of each pair of the cut-and-raised parts is larger than an outer diameter of each of the upstream pipe body parts. In addition, each pair of the cut-and-raised parts are inclined such that a width between downstream end parts becomes smaller than the width between the upstream end parts. A heating gas passing part having a width narrower than a dimension therebetween is provided in a region between two adjacent upstream pipe body parts.

A water heating device equipped with a housing, a fan and a chamber arranged in the interior of the housing, and screws. The housing has first and second side plates which oppose one another in a first direction and extend from the ends of a back plate along a second direction intersecting the first direction. An opening part is provided in the housing on the side opposite the back plate in the second direction. The fan has a discharge opening, a first flow passage extending along the first direction, and a first flange. The chamber has an intake opening, a second flow passage extending along the first direction, and a second flange. The first and the second flanges are secured by screws. In a planar view, the center axis of the screws is slanted such that a head portion is closer to the opening part than the tip-end portion.

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.