A damper control device may include an appliance control programmed processor for controlling a gas burner, the appliance control programmed processor including a lockout register for storing electronic data information, and a damper control programmed processor for controlling a damper, the damper control programmed processor including a damper request register for storing electronic data information. The damper control programmed processor may be configured for selectively opening or closing the damper responsive to status of the damper request register and controlling status of the lockout register to indicate status of the damper, and the appliance control programmed processor may be configured for controlling status of the damper request register responsive to a call for operation of the gas burner and operating the gas burner only if the lockout register is in an unlock status.

An integrated damper control system is used with a gas fired appliance including a gas burner, a flue and a damper for selectively opening the flue. The damper control system comprises an appliance control including a programmed processor for controlling the gas burner and a communication interface device. A damper control comprises a programmed processor for controlling the damper and a communication interface device for communication with the appliance control communication interface device. The damper control programmed processor is programmed to selectively open or close the damper responsive to status of a damper request register and to control status of a lockout register to indicate status of the damper. The appliance control programmed processor is programmed to control status of the damper request register responsive to a call for operation of the gas burner and to operate the gas burner only if the lockout register is set to unlock.

A fan heater for heating using exhaust waste heat, including: a natural exhaust tube discharging some exhaust gas from a water heater; a forced exhaust tube connected to the natural exhaust tube in a parallel structure, the remaining exhaust gas, excluding naturally discharged exhaust gas, flowing into the forced exhaust tube; a heat exchange device on the upper portion of the forced exhaust tube and supplied with high-temperature exhaust gas; a forced exhaust blower installed on the heat exchange device to draw exhaust gas from the forced exhaust tube and discharge it; a main unit having the heat exchange device embedded therein and having a circulation unit such that low-temperature indoor air circulates into the heat exchange device; a warm-air circulation blower supplying the indoor air towards the outer air circulation unit and circulating the low-temperature indoor air so the exhaust gas exchanges heat; and a control unit.

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.

A heat exchange flue has a top flue gas chamber, a bottom flue gas chamber, and a heat exchange section located therebetween that includes a heat exchange tube bundle located in the middle and a left side flue and a right side flue located at two sides of the heat exchange tube bundle. The axis of the heat exchange tube bundle is positioned in a vertical plane extending substantially forward and backward, allowing the flue gas to laterally flush against the surfaces of heat exchange tubes. The left and right side flues are in a vertical box shape, and the flues are each provided with a plurality of flue gas dampers (3). Each of the flue gas dampers is provided with a flue gas damper frame for defining a flue gas port and a flue gas port opening/closing device capable of selectively opening and closing the flue gas port.

A combustion system including a bypass which opens to the open air during two different operating modes (conventional combustion; oxy-combustion), and which has the function, on the one hand, in the two operating modes, when the discharge valve is at least partially open and the recycling valve is closed or open, of allowing air to enter the recycling loop, and which has the function, on the other hand, in the second operating mode, when the discharge valve is closed and the recycling valve is open, of allowing a surplus of the combustion gas produced by the combustion device to be discharged from the recycling loop, the other fraction of the combustion gas produced by the combustion device supplying the mixer.