Abstract: A conduit made of a synthetic resin, having an inner surface and an outer surface, having concave portions and convex portions alternately and continuously provided in the length direction. The conduit is bendable. The conduit includes outer wall parts extending with a first width in the length direction; inner wall parts positioned radially inside relative to the outer wall parts and extending with a second width in the length direction; and side wall parts joining the outer wall parts and the inner wall parts so that the outer wall parts and the inner wall parts are alternately and continuously provided in the length direction. The outer surfaces of the outer wall parts each have, at both ends in the length direction, protruding parts, which protrude in the radial direction.

Abstract: An exhaust connection structure is constructed to connect a combustion apparatus and an exhaust tube having projections and recesses in an outer surface. The exhaust connection structure has a sealing member arranged on an outer circumferential surface of the exhaust tube and an exhaust joint arranged to sandwich the sealing member between the exhaust joint and the outer circumferential surface of the exhaust tube. The exhaust joint includes an engagement member and the engagement member has an annular portion and an engaging portion bent toward an inner circumference of the annular portion. The engaging portion is engaged with the projections and recesses in the exhaust tube.

Abstract: An exhaust connection structure is constructed to connect a combustion apparatus and an exhaust tube having projections and recesses in an outer surface. The exhaust connection structure has a sealing member arranged on an outer circumferential surface of the exhaust tube and an exhaust joint arranged to sandwich the sealing member between the exhaust joint and the outer circumferential surface of the exhaust tube. The exhaust joint includes an engagement member and the engagement member has an annular portion and an engaging portion bent toward an inner circumference of the annular portion. The engaging portion is engaged with the projections and recesses in the exhaust tube.