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.

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.

A water heating apparatus includes: a water heating circuit; a heater for heating the water heating circuit; and a controller for controlling the water heating apparatus. The water heating circuit includes a heat exchanger for heating a fluid including water and hot water, and a pipe for supplying the fluid via the heat exchanger. The controller is configured to drive the heater in a cleaning mode in which a cleaning liquid for cleaning an inside of the heat exchanger is supplied to the heat exchanger through the pipe.

A baffle device for a flue and a gas water heating device includes a baffle plate, a driving mechanism and a detecting mechanism. The driving mechanism is configured to rotate the baffle in the flue. The detecting mechanism includes a photoelectric sensor to detect the position state of the baffle device in the flue.

A baffle device for a flue and a gas water heating device includes a baffle plate, a driving mechanism and a detecting mechanism. The driving mechanism is configured to rotate the baffle in the flue. The detecting mechanism includes a photoelectric sensor to detect the position state of the baffle device in the flue.

A furnace system includes a heat exchanger and a burner assembly including a burner enclosure fluidly coupled to the heat exchanger. The burner assembly is configured to receive a fluid, ignite the fluid to produce combustion byproducts, and direct the combustion byproducts to the heat exchanger. The furnace system also includes a pressure sensor configured to detect a pressure within the burner enclosure. The furnace system is configured to operate based on the pressure detected by the pressure sensor.

Provided is a gas water heater. The gas water heater includes a pre-mixer, a combustor having a combustion chamber in communication with a premixing chamber, a condensate water assembly configured to receive and discharge condensate water, and an apparatus for controlling the gas water heater. The pre-mixer includes a premixing chamber and an air intake fan that is configured to supply air to the combustion chamber. The air intake fan is disposed in the premixing chamber. The method includes: acquiring an intake air pressure threshold; acquiring an air intake pressure value of the air intake fan; and controlling, in response to determining based on the air intake pressure value and the intake air pressure threshold that a water seal of the condensate water assembly is at risk of being blown away, the gas water heater to stop operation.

Provided is a gas water heater. The gas water heater includes a pre-mixer, a combustor having a combustion chamber in communication with a premixing chamber, a condensate water assembly configured to receive and discharge condensate water, and an apparatus for controlling the gas water heater. The pre-mixer includes a premixing chamber and an air intake fan that is configured to supply air to the combustion chamber. The air intake fan is disposed in the premixing chamber. The method includes: acquiring an intake air pressure threshold; acquiring an air intake pressure value of the air intake fan; and controlling, in response to determining based on the air intake pressure value and the intake air pressure threshold that a water seal of the condensate water assembly is at risk of being blown away, the gas water heater to stop operation.