| 摘要 |
PROBLEM TO BE SOLVED: To prevent the occurrence of errors in connection, when a separate type supply and exhaust pipe extending from a combustion apparatus is connected to a top of a supply and exhaust tube. SOLUTION: At a connection part, wherein an air feed pipe 4 extending from the combustion apparatus 2 side and an exhaust pipe 5 are connected to a top 6 of an air supply and exhaust tube, for example, instead of making both the air feed pipe 4 and the exhaust pipe 5 are set as male port, one of them is set as a female port as an error connection prevention mechanism between an air feed pipe connection port 7a and an exhaust pipe connection port 8a of the top 6 of an air supply and exhaust tube, and exhaust tube connection ends 4b and 5b of the air feed pipe 4 and the exhaust pipe 5.
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