A controller is configured to set total stop in which operations of all of a plurality of water heaters are stopped when an abnormal condition of a fan or an abnormal condition in communication is sensed in any of the plurality of water heaters while at least one of the plurality of water heaters is operating. The controller is further configured not to set total stop when an abnormal condition of the fan or an abnormal condition in communication is sensed in at least one of the plurality of water heaters while a sensing element for sensing a backflow of an exhaust from an exhaust path assembly is connected to the controller.

A combustion device includes a combustion control section which controls combustion in the combustion device; a setting section operated to set information indicating whether or not a plurality of combustion devices are in a common vent discharge state; and a memory section which stores therein connection configurations with the other combustion control sections to which the combustion control section is communicatively connected, and the combustion control section determines whether or not the combustion control section can communicate with a linkage control section or the other combustion control sections, and inhibits combustion in the combustion device to which the combustion control section belongs, in a case where the combustion control section determines that the combustion control section cannot communicate with the linkage control section or at least one of the other combustion control sections and the common vent discharge state is set by the setting section.