Latent heat exchanger and water heater

Abstract

A latent heat exchanger ( 1 ) has a casing ( 2 ), a heat-absorbing tube ( 50 ) accommodated in the casing ( 2 ), an inlet header ( 60 ), and an outlet header ( 70 ). The casing ( 2 ) has a casing main body ( 10 ) and a top plate ( 40 ) closing an upper opening ( 16 ) of the casing main body ( 10 ). The back wall ( 11 ), the front wall ( 12 ), the bottom wall ( 13 ), one side wall ( 14 ), and the other side wall ( 15 ) of the casing main body ( 10 ) are formed integrally by draw-processing a single metal plate.

1 . A latent heat exchanger comprising:
 a casing having a flow path of combustion gas therein;   a heat absorbing pipe accommodated in the casing;   an inlet header for introducing fluid to be heated into the heat absorbing pipe; and   an outlet header for discharging the fluid to be heated from the heat absorbing pipe, wherein   the casing has a box-shaped casing body having an upper opening and a top board closing the upper opening of the casing body,   the casing body has a back wall, a front wall, a bottom wall having a drain discharging opening, one side wall having an upstream end-inserting hole through which an upstream end of the heat absorbing pipe is inserted and a downstream end-inserting hole through which a downstream end of the heat absorbing pipe is inserted, and the other side wall,   the back wall, the front wall, the bottom wall, the one side wall, and the other side wall are integrally formed by drawing one single metal plate, and   the inlet header and the outlet header are respectively disposed outside the one side wall and connected to the upstream and downstream ends of the heat absorbing pipe led outside the one side wall through the upstream end-inserting hole and the downstream end-inserting hole.   
     
     
         2 . The latent heat exchanger according to  claim 1 , wherein
 the casing body and the top board are connected by a fastening process.   
     
     
         3 . The latent heat exchanger according to  claim 1 , wherein
 the heat absorbing pipe in the casing has a piping structure in which a straight portion extending between the one side wall and the other side wall and circularly arcuate turn-around portions located at both ends on one side wall side and the other side wall side are repeated consecutively.   
     
     
         4 . The latent heat exchanger according to  claim 3 , further comprising a side baffle plate in a plate shape between the circularly arcuate turn-around portion located on the other side wall side and an inner surface of the other side wall. 
     
     
         5 . The latent heat exchanger according to  claim 4 , wherein
 the back wall has a combustion gas inlet port for introducing the combustion gas into the casing,   the front wall has a combustion gas outlet port for discharging the combustion gas out of the casing, and   the side baffle plate has inclined faces inclined from ends on an inlet port side and an outlet port side toward a heat absorbing pipe side.   
     
     
         6 . The latent heat exchanger according to  claim 4 , wherein
 an upper end of the side baffle plate is connected to a lower surface of the top board, and   a lower end of the side baffle plate does not abut an inner surface of the bottom wall.   
     
     
         7 . A water heater having the latent heat exchanger according to  claim 1 . 
     
     
         8 . The latent heat exchanger according to  claim 1 , wherein
 the top board and the bottom wall respectively have an upper protrusion and an lower protrusion, protruding inwardly into the casing, and   the upper protrusion abuts the uppermost circularly arcuate turn-around portion on a top board side and the lower protrusion abuts the bottommost circularly arcuate turn-around portion on a bottom wall side.   
     
     
         9 . The latent heat exchanger according to  claim 5 , further comprising an upper baffle plate inclined downward from a lower surface of the top board on a front wall side toward an upper edge of an opening of the gas outlet port. 
     
     
         10 . The latent heat exchanger according to  claim 3 , wherein
 a plurality of the heat absorbing pipes are accommodated in the casing, wherein   the circularly arcuate turn-around portions of the heat absorbing pipes each have a cross section flattened in a direction that the heat absorbing pipes are stacked one another, and   the heat absorbing pipes are stacked at the flattened circularly arcuate turn-around portions between the top board and the bottom wall.   
     
     
         11 . A method of manufacturing the latent heat exchanger according to  claim 1 , comprising the steps of:
 inserting the upstream and downstream ends of the heat absorbing pipe through the upstream end-inserting hole and the downstream end-inserting hole of the one side wall respectively;   leading the upstream and downstream ends of the heat absorbing pipe outside the one side wall;   applying a brazing material to boundaries between outer surfaces of the led-out heat absorbing pipe and the upstream ends-inserting hole and the downstream ends-inserting hole;   inserting the upstream and the downstream ends of the led-out heat absorbing pipe through connection holes of header main bodies of the inlet and outlet headers respectively:   applying a brazing material to boundaries between outer surfaces of the upstream and downstream ends of the heat absorbing pipe and the connection holes;   closing openings of the header main bodies with header covers respectively;   applying a brazing material to boundaries between inner surfaces of main body peripheral walls of the header main bodies and outer surfaces of cover peripheral walls of the header covers;   closing the upper opening of the casing body with the top board to form a subassembly in which the casing body, the top board, the heat absorbing pipe, the inlet header, and the outlet header are integrally formed; and   heating the subassembly in a heating furnace.