A closing member includes an annular portion and a flange portion. The annular portion is provided with a through hole and is in contact with an outer circumferential surface of an exhaust tube in at least a part of the through hole. The flange portion extends from an outer circumferential surface of the annular portion toward an outer side and is larger in outer diameter than an exhaust pipe. The flange portion contacts a tip end portion of the exhaust pipe on outside of a building so as to close a gap between the exhaust pipe and the exhaust tube. The flange portion is formed to protrude toward an outer side such that an entire circumference of the flange portion extends beyond an outer circumferential surface of the tip end portion of the exhaust pipe.

A fume exhaust assembly for a gas water heater. The fume exhaust assembly comprises a fume exhaust hood; the fume exhaust hood is provided with a fume exhaust pipe; the fume exhaust pipe and the fume exhaust hood are integrally formed. By means of integral formation, an assembly operation for the fume exhaust pipe and the fume exhaust hood is saved, an assembly procedure of a gas water heater product is simplified, and thus the production efficiency of the gas water heater product can be improved.

A fume exhaust assembly for a gas water heater. The fume exhaust assembly comprises a fume exhaust hood; the fume exhaust hood is provided with a fume exhaust pipe; the fume exhaust pipe and the fume exhaust hood are integrally formed. By means of integral formation, an assembly operation for the fume exhaust pipe and the fume exhaust hood is saved, an assembly procedure of a gas water heater product is simplified, and thus the production efficiency of the gas water heater product can be improved.

A reverse combustion type combustion apparatus (1) includes a combustion section (2) that combusts fuel in a downward direction, heat exchangers (4, 5) disposed under the combustion section (2), and an exhaust box (6) disposed under the heat exchangers (4, 5). The exhaust box (6) is a molded product made from a synthetic resin material; the exhaust box (6) includes an opening portion (30) for introduction of combustion exhaust gases generated by an upper portion, a fixing portion (33) for fixing the heat exchanger (5), and an inclined bottom portion (35) that collects condensed water generated by the heat exchanger (5); and, at the lower end portion of the exhaust box (6), at least three legs (40) are integrally formed and make the exhaust box (6) stand up by itself.

A closing member includes an annular portion and a flange portion. The annular portion is provided with a through hole and is in contact with an outer circumferential surface of an exhaust tube in at least a part of the through hole. The flange portion extends from an outer circumferential surface of the annular portion toward an outer side and is larger in outer diameter than an exhaust pipe. The flange portion contacts a tip end portion of the exhaust pipe on outside of a building so as to close a gap between the exhaust pipe and the exhaust tube. The flange portion is formed to protrude toward an outer side such that an entire circumference of the flange portion extends beyond an outer circumferential surface of the tip end portion of the exhaust pipe.

A reverse combustion type combustion apparatus (1) includes a combustion section (2) that combusts fuel in a downward direction, heat exchangers (4, 5) disposed under the combustion section (2), and an exhaust box (6) disposed under the heat exchangers (4, 5). The exhaust box (6) is a molded product made from a synthetic resin material; the exhaust box (6) includes an opening portion (30) for introduction of combustion exhaust gases generated by an upper portion, a fixing portion (33) for fixing the heat exchanger (5), and an inclined bottom portion (35) that collects condensed water generated by the heat exchanger (5); and, at the lower end portion of the exhaust box (6), at least three legs (40) are integrally formed and make the exhaust box (6) stand up by itself.

A non-return valve for a flow channel has a housing and an outflow opening that can be closed by a pivoting blocking flap. The blocking flap has a dome-shaped bulge. An opening edge of the outflow opening has a hinge region for the blocking flap that transitions into a blocking flap stop region circumferentially opposite the hinge region. The blocking flap stop region is offset so that the opening edge has a progression that is curved in the circumferential direction and in the outflow direction. The housing has an indentation in the circumferential direction, which is not closed by the blocking flap such that the indentation forms a condensate chamber when the housing is inserted into the surrounding flow channel. The indentation is equipped with a flow opening, through which a condensate accumulating in the condensate chamber delimited by the indentation can flow in the interior of the housing.

A non-return valve for a flow channel has a housing and an outflow opening that can be closed by a pivoting blocking flap. The blocking flap has a dome-shaped bulge. An opening edge of the outflow opening has a hinge region for the blocking flap that transitions into a blocking flap stop region circumferentially opposite the hinge region. The blocking flap stop region is offset so that the opening edge has a progression that is curved in the circumferential direction and in the outflow direction. The housing has an indentation in the circumferential direction, which is not closed by the blocking flap such that the indentation forms a condensate chamber when the housing is inserted into the surrounding flow channel. The indentation is equipped with a flow opening, through which a condensate accumulating in the condensate chamber delimited by the indentation can flow in the interior of the housing.