A flue damper may include a flue pipe with a first side leading to an outlet of the flue damper and a second side leading to an inlet of the flue damper. A damper gate may be included and have an open state and a closed state, where in the open state, the first side of the flue pipe is in fluid communication with the second side, and where in the closed state, the damper gate interrupts fluid communication between the first side and the second side. A float may be secured to an upper surface of the damper gate. The upper surface of the damper gate may face the first side of the flue pipe when the damper gate is in the closed state such that the damper gate at least partially opens when condensate collects within the first side of the flue pipe.

A flue damper may include a vent pipe with a first side leading to an outlet of the flue damper and a second side leading to an inlet of the flue damper. A damper gate of the flue damper may be movable between an open state and a closed state, where in the open state, the first side of the vent pipe is in fluid communication with the second side, and where in the closed state, the damper gate interrupts fluid communication between the first side and the second side. A drainage port may also be included, and a plug may be movable relative to the drainage port to selectively seal the drainage port when the damper gate remains in the closed state.

A flue damper may include a flue pipe with a first side leading to an outlet of the flue damper and a second side leading to an inlet of the flue damper. A damper gate may be included and have an open state and a closed state, where in the open state, the first side of the flue pipe is in fluid communication with the second side, and where in the closed state, the damper gate interrupts fluid communication between the first side and the second side. A float may be secured to an upper surface of the damper gate. The upper surface of the damper gate may face the first side of the flue pipe when the damper gate is in the closed state such that the damper gate at least partially opens when condensate collects within the first side of the flue pipe.

The invention relates to an arrangement (1) including two burners (10), which has a common exhaust gas guiding device (2) and a common supply device (3) for combustion air. A backflow barrier (4) blocks a flow of a gaseous medium in a flow direction and is arranged in the exhaust gas guiding device (2) or in the supply device (3). The backflow barrier (4) has an opening (40) and a movable element (41) which is movable between two positions. The opening (40) is open in case the movable element (41) is in one of the two positions and closed in case the movable element (41) is in another of the two positions.

The combustion device includes: a burner; an igniter; a fuel supply unit that supplies fuel to the burner; a blower fan that supplies air for combustion; an exhaust port that discharges combustion exhaust; a device control unit that, before ignition of fuel supplied to the burner by operation of the igniter, performs air purge of the burner at a predetermined air blowing amount by driving the blower fan; and a setting means that is set when a check valve for preventing back flow of exhaust is connected to the exhaust port. When the setting means is set to indicate that the check valve is connected, the device control unit controls the operation of the blower fan so that slow-start air purge is performed in which the time interval from the start of air purge until the predetermined air blowing amount is reached becomes longer, than in the case in which no such check valve is connected.

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.

The invention relates to an arrangement (1) including two burners (10), which has a common exhaust gas guiding device (2) and a common supply device (3) for combustion air. A backflow barrier (4) blocks a flow of a gaseous medium in a flow direction and is arranged in the exhaust gas guiding device (2) or in the supply device (3). The backflow barrier (4) has an opening (40) and a movable element (41) which is movable between two positions. The opening (40) is open in case the movable element (41) is in one of the two positions and closed in case the movable element (41) is in another of the two positions.

A flue damper may include a vent pipe with a first side leading to an outlet of the flue damper and a second side leading to an inlet of the flue damper. The flue damper may further include a damper gate with an open state and a closed state, where in the open state, the first side of the vent pipe is in fluid communication with the second side, and where in the closed state, the damper gate interrupts fluid communication between the first side and the second side. A seat flange may be located on an inner wall of the vent pipe, and a seal may be fixed to an outer edge of the damper gate, where a through-portion of the seal extends through a first perforation in the outer edge of the damper gate.

The combustion device includes: a burner; an igniter; a fuel supply unit that supplies fuel to the burner; a blower fan that supplies air for combustion; an exhaust port that discharges combustion exhaust; a device control unit that, before ignition of fuel supplied to the burner by operation of the igniter, performs air purge of the burner at a predetermined air blowing amount by driving the blower fan; and a setting means that is set when a check valve for preventing back flow of exhaust is connected to the exhaust port. When the setting means is set to indicate that the check valve is connected, the device control unit controls the operation of the blower fan so that slow-start air purge is performed in which the time interval from the start of air purge until the predetermined air blowing amount is reached becomes longer, than in the case in which no such check valve is connected.

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.