In a heat source apparatus in which an electric component having an electrode and an insulator is mounted on a side plate of a combustion box, in a state in which a packing is interposed between a flange portion of the insulator and the side plate, by fastening a clamp which overlaps with an outer surface of the flange portion, to the side plate, the temperature rise in the clamp is restrained. Upper and lower water tubes constituting a part of a water jacket are disposed on the side plate on upper and lower sides of the position of mounting the electrode component. In case the upper and lower water tubes are disposed on an inside surface of the side plate, the upper and lower parts of the clamp are brought into contact with those disposed positions of the water tubes which are in upper and lower portions of the side plate and, in case the upper and lower water tubes are disposed on an outside of the side plate, the upper and lower parts of the clamp are brought into contact with the upper and lower water tubes.

In a heat source apparatus in which an electric component having an electrode and an insulator is mounted on a side plate of a combustion box, in a state in which a packing is interposed between a flange portion of the insulator and the side plate, by fastening to the side plate a clamp which overlaps with an outer surface of the flange portion, the packing is prevented from getting spread when compressed, thereby securing good sealing properties. Upper and lower water tubes constituting a part of a water jacket are disposed on a side plate on upper and lower sides of the mounting position of the electrode component. In case the upper and lower water tubes are disposed on an inside surface of the side plate, upper and lower side edge portions of the packing are in contact with those upper and lower swelled-out portions formed in the one-side side plate which are swollen outward for respectively receiving into recesses the upper and lower water tubes; and that, in case the upper and lower water tubes are disposed on an outside surface of the side plate, upper and lower side edge portions of the packing are in contact with the upper and lower water tubes.

A hot water apparatus includes a burner, a latent heat recovery heat exchanger, a housing, a fixing member, an attachment member, and a straightening vane. The fixing member is configured to fix the latent heat recovery heat exchanger to the housing. The attachment member is configured to attach the fixing member to a case. The straightening vane is arranged in the case. The attachment member protrudes into the case. The straightening vane includes a top plate portion arranged upstream from the attachment member in a direction of flow of the heating gas in the case.

A latent heat recovery heat exchanger includes a case, a heat exchange portion, and a straightening vane. The heat exchange portion includes a plurality of heat transfer plates surrounded by a peripheral wall portion of the case and layered on one another, each of the plurality of heat transfer plates extending in a direction from an inlet toward an outlet. The straightening vane includes a top plate portion covering the plurality of heat transfer plates so as to close a space between the plurality of heat transfer plates in end portions of the plurality of heat transfer plates in a direction intersecting with a direction of layering of the plurality of heat transfer plates when the heat exchange portion is viewed from the inlet toward the outlet.

A coil support member is attached to a coil inside a water storage vessel and includes multiple openings, insertion portions and a non-insertion portion. The openings are arranged in a lengthwise direction, and together with surrounding sites prevent contact between mutually adjacent loops of the tube of the coil and suppress contact between an inner surface of the water storage vessel and an outer surface of the coil. The insertion portions are formed between the openings and are inserted into an intra-coil space located radially inward of the outer surface of the coil. The non-insertion portion is positioned in an extra-coil space located radially outward of the outer surface of the coil. The insertion portions have insertion body portions preventing contact between mutually adjacent loops of the tube, and engagement portions contacting the tube from the intra-coil space and maintaining an inserted state of the insertion body portions.

A water heater (1) includes a housing (8), combustion devices (31, 32), heat exchangers (41A to 42B), a water supply pipe (P1), a hot water supply pipe (P2), a water supply connection member (10), a hot water supply connection member (20), a water quantity control part (50), and a fine bubble generator (9) in fluid connection with either the water supply pipe (P1) or the hot water supply pipe (P2). The fine bubble generator (9) has an inflow port (91H), into which hot water flows from an upstream side (P2U), and an outflow port (92H), out of which hot water containing the fine bubbles is discharged to a downstream side (P2D). The fine bubble generator (9) is located below burner ports (31F, 32F) of the combustion devices.

A water heater (1) includes a housing (8), combustion devices (31, 32), heat exchangers (41A to 42B), a water supply pipe (P1), a hot water supply pipe (P2), a water supply connection member (10), a hot water supply connection member (20), a water quantity control part (50), and a fine bubble generator (9) in fluid connection with either the water supply pipe (P1) or the hot water supply pipe (P2). The fine bubble generator (9) has an inflow port (91H), into which hot water flows from an upstream side (P2U), and an outflow port (92H), out of which hot water containing the fine bubbles is discharged to a downstream side (P2D). The fine bubble generator (9) is located below burner ports (31F, 32F) of the combustion devices.

A water heater according to the present invention comprises: a combustion chamber; a burner provided to cause a combustion reaction in the combustion chamber; a plurality of circulation pipes that communicate with the combustion chamber so that combustion gas generated by the combustion reaction flows through the inside; a circulation housing that surrounds the plurality of circulation tubes and the combustion chamber so that circulating water flows to the surroundings of the plurality of circulation tubes and the combustion chamber; a pre-stage heat exchanger that communicates with the plurality of circulation tubes to exchange heat between direct water and combustion gas passing through the plurality of circulation tubes to generate pre-stage hot water; and a main heat exchanger that is connected to the pre-stage heat exchanger and the circulation housing, to generate hot water by exchanging heat between the hot water received from the pre-stage heat exchanger and the hot water delivered from the circulation housing.

A water heater according to the present invention comprises: a combustion chamber; a burner provided to cause a combustion reaction in the combustion chamber; a plurality of circulation pipes that communicate with the combustion chamber so that combustion gas generated by the combustion reaction flows through the inside; a circulation housing that surrounds the plurality of circulation tubes and the combustion chamber so that circulating water flows to the surroundings of the plurality of circulation tubes and the combustion chamber; a pre-stage heat exchanger that communicates with the plurality of circulation tubes to exchange heat between direct water and combustion gas passing through the plurality of circulation tubes to generate pre-stage hot water; and a main heat exchanger that is connected to the pre-stage heat exchanger and the circulation housing, to generate hot water by exchanging heat between the hot water received from the pre-stage heat exchanger and the hot water delivered from the circulation housing.

A thermal insulation material is arranged on an inner surface of a swelling part formed at a side plate part and outwardly swelling in an X-axis direction so as to be sandwiched from both sides in a Z-axis direction by a step outwardly bent in the X-axis direction and positioned an end, in a Z-axis plus direction, of the swelling part and by a structural member of a burner protruding inwardly in the X-axis direction from an end, in the Z-axis minus direction, of the side plate part. A vicinity portion of an end, in the Z-axis plus direction, of the thermal insulation material is held from an inside in the X-axis direction by a side edge portion, on each side in the X-axis direction, of the fins.