| 摘要 |
PROBLEM TO BE SOLVED: To easily remove a supply and exhaust tube main body and a supply and exhaust tube top, with respect to the supply and exhaust tube of a double tube structure composed of the supply and exhaust tube main body and the supply and exhaust tube top. SOLUTION: In the supply and exhaust tube for performing exhausting after combustion and air supply for combustion from the outdoors through the supply and exhaust device 1 of the double tube structure comprising the supply and exhaust tube main body 4 and the supply and exhaust tube top 5 penetrating through a through hole 3 of a wall 2, a ring-shaped recessed portion 18 is formed on a tip portion of an inner exhaust tube 6 of the supply and exhaust tube main body 4 closely kept into contact with and fitted to an outer exhaust tube 12 of the supply and exhaust tube top 5, thus dew condensation water including impurities is prevented from intruding and being firmly fixed to the whole fitting portion of the inner exhaust tube 6 of the supply and exhaust tube main body 4 and the outer exhaust tube 12 of the supply and exhaust tube top 5, and the work for removing the supply and exhaust tube main body 4 and the supply and exhaust tube top 5 from the wall 2 can be easily performed. COPYRIGHT: (C)2008,JPO&INPIT
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