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 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.