Disclosed are a gas furnace and an air conditioner having the same. The gas furnace includes: a fuel valve; a manifold providing a passage of fuel passing through the fuel valve; a plurality of burners provided to burn fuel provided from the manifold and spaced apart from each other in one direction; a plurality of heat exchangers providing a passage of combustion gas generated by the plurality of burners; and a blower for causing a flow of air passing around the heat exchanger. The manifold includes: a first tube having one end connected to the fuel valve and forming a first passage; a second tube extending in the one direction, forming a second passage, and facing at least one of the plurality of burners; a third tube extending in the one direction, forming a third passage, and facing remaining burners of the plurality of burners; and a three-way valve connected to the first tube, the second tube, and the third tube.

A temperature sensor detects the presence of a flame by measuring the temperature near the flame site, and an actuator positions an ignition device in based on the temperature sensor's reading. The ignition device is positioned near the flame site if the flame is not present and further from the flame site if the flame is present.

A method and apparatus for a gas burner head with at least a first burner region and a second burner region, an ignitor located near the gas burner, and a burner drive that is configured to generate relative rotation between the first and second burner regions of the gas burner to transfer a flame between the first and second burner regions during the relative rotation.

Described herein are methods and systems for using pyrophoric liquids to ignite combustible gas.

A method and apparatus for a gas burner head with at least a first burner region and a second burner region, an ignitor located near the gas burner, and a burner drive that is configured to generate relative rotation between the first and second burner regions of the gas burner to transfer a flame between the first and second burner regions during the relative rotation.

A flame detection system is designed to detect leakage in flame sense circuits. The flame detection system includes a flame sensor, an amplifier, a detection circuit, and a microcontroller. Flame sense circuitry use operational amplifiers that needs negative voltage supply for its operation. Negative supply voltage properly measures negative input signals. Once a leakage current in the flame detection system is determined a shutdown signal is provided to shut down a flame sensor when the leakage current condition is determined.

A start system for an expendable gas turbine engine is provided. The start system may include: a tank configured to store a pressurized gas comprising oxygen; a non-pyrotechnic igniter in communication with a combustion chamber of the expendable gas turbine engine; a starter tube configured to feed the pressurized gas from the tank into the combustion chamber; and a valve configured to regulate a flow of the pressurized gas from the tank into the starter tube; wherein, the start system is configured to startup the expendable gas turbine engine by the flow of the pressurized gas from the tank, through the valve and the starter tube, into the combustion chamber and, from the combustion chamber, into a plurality of turbine blades of the expendable gas turbine engine, and by ignition, by the non-pyrotechnic igniter, of fuel injected into the combustion chamber.

A combustion system for a coal fired furnace having a windbox includes a source of a mixture of pulverized coal and air, and a splitter that receives the mixture and splits it into first and second mixed streams. A first nozzle receives the first mixed stream and discharges it into the furnace. A separator receives the second mixed stream and separates it into an air stream and a coal rich stream. An air conduit connected between the separator and the source of the mixture causes at least some of the air stream to be fed back into the mixture. A second nozzle receives the coal rich stream and discharges it into the furnace. A third nozzle receives support air from the windbox and discharges it into the furnace in a combustion supporting relationship with respect to the coal rich stream.

A flame detection system is designed to detect leakage in flame sense circuits. The flame detection system includes a flame sensor, an amplifier, a detection circuit, and a microcontroller. Flame sense circuitry use operational amplifiers that needs negative voltage supply for its operation. Negative supply voltage properly measures negative input signals. Once a leakage current in the flame detection system is determined a shutdown signal is provided to shut down a flame sensor when the leakage current condition is determined.

Described herein are methods and systems for using pyrophoric liquids to ignite combustible gas.