COLLECTIVE EXHAUST SYSTEM

The disclosure provides a collective exhaust system capable of safely detecting a closing failure of a check valve of the collective exhaust system. The collective exhaust system includes: multiple combustion devices including blowing parts and exhaust pipes; a collective exhaust duct to which the exhaust pipes of the multiple combustion devices are respectively connected; and check valves respectively provided between the exhaust pipes and the collective exhaust duct. The collective exhaust system is configured to detect a closing failure of the check valves by performing, in a state where one of the blowing parts of the multiple combustion devices is stopped and all the other blowing parts are driven with a predetermined blower capacity, a backflow determination from the collective exhaust duct to the combustion device with the stopped blowing part, and by performing the backflow determination for the multiple combustion devices.