Exhaust adapter

An exhaust adapter comprising:

• a cylindrical part for connecting an exhaust pipe of a combustion device to a collective exhaust duct for collecting and discharging exhaust of a plurality of the combustion devices;
• and
• a backflow prevention structure for preventing backflow of the exhaust from the collective exhaust duct side to the exhaust pipe side,
• wherein the backflow prevention structure comprises:
• a damper receiving part formed with an opening through which the exhaust from the exhaust pipe passes;
• an exhaust damper plate that opens the opening by pressure of the exhaust from the exhaust pipe and closes the opening by its own weight when there is no exhaust from the exhaust pipe;
• a support shaft that rotatably supports the exhaust damper plate;
• and
• a bearing part that supports the support shaft,
• wherein the exhaust damper plate comprises a pair of shaft hole parts for inserting the support shaft, and
• the pair of shaft hole parts is formed in a long hole shape that is long in a vertical direction with respect to the support shaft when the exhaust damper plate is in a posture in which the opening is closed.