A flexible hose liner is provided having a cylindrical body extending along a longitudinal axis from a first end to a second end. First and second sleeves form the cylindrical body by separate continuous ribbons having a plurality of convolutions formed in a helical pattern along the cylindrical body from the first end to the second end. A ring is formed in each revolution about the longitudinal axis of the continuous ribbon of the first and second sleeves. A plurality of rings form the cylindrical body, each ring has a first convolution and an ending convolution such that a mechanical connection is formed between the ending convolution of a preceding ring and the first convolution of a succeeding ring. The mechanical connection of the between the rings of the first sleeve being different from the mechanical connection of the rings of the second sleeve.

A flexible hose liner is provided having a cylindrical body extending along a longitudinal axis from a first end to a second end. First and second sleeves form the cylindrical body by separate continuous ribbons having a plurality of convolutions formed in a helical pattern along the cylindrical body from the first end to the second end. A ring is formed in each revolution about the longitudinal axis of the continuous ribbon of the first and second sleeves. A plurality of rings form the cylindrical body, each ring has a first convolution and an ending convolution such that a mechanical connection is formed between the ending convolution of a preceding ring and the first convolution of a succeeding ring. The mechanical connection of the between the rings of the first sleeve being different from the mechanical connection of the rings of the second sleeve.

A flexible hose liner is provided having a cylindrical body extending along a longitudinal axis from as first end to a second end. First and second sleeves form the cylindrical body by separate continuous ribbons having a plurality of convolutions formed in a helical pattern along the cylindrical body from the first end to the second end. A ring is formed in each revolution about the longitudinal axis of the continuous ribbon of the first and second sleeves. A plurality of rings form the cylindrical body, each ring has a first convolution and an ending convolution such that a mechanical connection is formed between the ending convolution of a preceding ring and the first convolution of a succeeding ring. The mechanical connection of the between the rings of the first sleeve being different from the mechanical connection of the rings of the second sleeve.

An exhaust tube includes one end portion and the other end portion and is connected at one end portion to a combustion apparatus, of which inside is defined as an exhaust passage for combustion gas. An exhaust pipe has an outer diameter greater than that of exhaust tube, into which a part of exhaust tube on a side of the other end portion is introduced. An exhaust adapter is attached between an outer circumferential surface of exhaust tube and an inner circumferential surface of exhaust pipe. On the side close to the other end portion in exhaust tube relative to exhaust adapter, an exhaust passage hole 1a is provided separately from an opening in the other end portion of exhaust tube. Exhaust passage hole has an opening area greater than a cross-sectional area of the exhaust passage and is in communication with the exhaust passage.