Abstract: 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.

Abstract: An exhaust adapter secures an exhaust tube relative to an exhaust pipe. The exhaust adapter is formed to have an annular shape enclosing a through hole, and is mounted on the outer peripheral surface of the exhaust tube and on the inner peripheral surface of the exhaust pipe by inserting the exhaust tube into the through hole. When the exhaust adapter is being fitted on the outer peripheral surface of the exhaust tube, the inner peripheral surface of the exhaust adapter presses the outer peripheral surface of the exhaust tube, and when the exhaust adapter is being fitted on the inner peripheral surface of the exhaust pipe, the outer peripheral surface of the exhaust adapter presses the inner peripheral surface of the exhaust pipe.

Abstract: The coupler is provided that has two ends or openings. On one end, the coupler is adapted for receiving a stainless steel pipe. The stainless steel pipe fits inside or into one end of the coupler and is securely and tightly held inside the coupler by a snap lock. An O-ring rests against the end of the stainless steel pipe and forms a seal when the stainless steel pipe is inserted into the coupler. On the other end, the coupler is adapted for receiving a plastic or PVC pipe. The plastic pipe fits inside a recessed opening of the coupler, and is securely and tightly held inside the coupler by a clamp lock or by glue. An O-ring rests against the end of the plastic pipe and forms a seal when the plastic pipe is inserted into the coupler.