Abstract: A water heating system includes a plurality of water heaters of which exhaust paths are connected in common to an exhaust path assembly, a control device configured for centralized control of the plurality of water heaters, and a non-volatile storage unit. The plurality of water heaters include control units configured to control hot water supply operations based on communication with the control device, respectively. The storage unit is configured to store information on the water heater of which control unit is recorded to have established communication with the control device. The control device turns off all of the plurality of water heaters when information on the water heater of which control unit has currently established communication with the control device does not match with the information stored in the storage unit.

Abstract: 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.

Abstract: A plurality of water heaters are connected in parallel with respect to a hot water supply path, and each of the plurality of water heaters has an exhaust path connected to an exhaust path assembly. Each of a plurality of sensing units is configured to be shifted from an electrically conducting state to an electrically non-conducting state when each of the plurality of sensing units senses an abnormal condition about air supply or exhaust. A series circuit of the plurality of sensing units is electrically connected in series to a resistance element between the power supply line and the ground line. The controller is configured to monitor an abnormal condition about air supply or exhaust based on a voltage on a node between the series circuit and the resistance element.

Abstract: 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.

Abstract: A control unit includes a scale detection unit for detecting, while the a burner provides combustion, occurrence of clogging with scale in a tube of a heat exchanger, and an output unit for outputting a result of a detection by the scale detection unit, a storage stores information including a numerical value representing how many times a surface temperature of the heat exchanger measured by a temperature measuring unit exceeds at least one of a plurality of threshold values. While the burner provides combustion when the surface temperature measured by the temperature measuring unit exceeds at least one of the plurality of threshold values the scale detection unit adds a predetermined value to the numerical value in the storage and when the numerical value attains a defined value or more the scale detection unit detects occurrence of clogging with scale.

Abstract: A water heating system includes a plurality of water heaters of which exhaust paths are connected in common to an exhaust path assembly, a control device configured for centralized control of the plurality of water heaters, and a non-volatile storage unit. The plurality of water heaters include control units configured to control hot water supply operations based on communication with the control device, respectively. The storage unit is configured to store information on the water heater of which control unit is recorded to have established communication with the control device. The control device turns off all of the plurality of water heaters when information on the water heater of which control unit has currently established communication with the control device does not match with the information stored in the storage unit.

Abstract: A plurality of water heaters are connected in parallel with respect to a hot water supply path, and each of the plurality of water heaters has an exhaust path connected to an exhaust path assembly. Each of a plurality of sensing units is configured to be shifted from an electrically conducting state to an electrically non-conducting state when each of the plurality of sensing units senses an abnormal condition about air supply or exhaust. A series circuit of the plurality of sensing units is electrically connected in series to a resistance element between the power supply line and the ground line. The controller is configured to monitor an abnormal condition about air supply or exhaust based on a voltage on a node between the series circuit and the resistance element.

Abstract: 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.

Abstract: 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.

Abstract: A control unit includes a scale detection unit for detecting, while the a burner provides combustion, occurrence of clogging with scale in a tube of a heat exchanger, and an output unit for outputting a result of a detection by the scale detection unit, a storage stores information including a numerical value representing how many times a surface temperature of the heat exchanger measured by a temperature measuring unit exceeds at least one of a plurality of threshold values. While the burner provides combustion when the surface temperature measured by the temperature measuring unit exceeds at least one of the plurality of threshold values the scale detection unit adds a predetermined value to the numerical value in the storage and when the numerical value attains a defined value or more the scale detection unit detects occurrence of clogging with scale.