Abstract: A fuel burner safe starting system which utilizes a pilot valve and a main valve is disclosed. A flame detection system operates in conjunction with a relay which properly ignites and operates the fuel burner system. In the event of a failure which improperly energizes the relay, the safe starting system prevents the fuel valves from opening.

Abstract: A flame rectification system is disclosed wherein a flame rod is used to detect the presence of a flame to control a relay or solenoid operated valve. Upon the initial indication of a flame, a pulse generating circuit momentarily overrides the flame rod signal and locks in the relay or valve. This allows the flame at the associated burner to stabilize before the relay or solenoid valve can close in the event of a momentary absence of a flame signal which could result from instability during the flame establishing process.

Abstract: A condition control system which utilizes digital logic to respond to the state of the condition being sensed. The control system utilizes a condition responsive element that is energized from an alternating current source and controls a first alternating current type of amplifier. The output of the amplifier is compared with a periodically generated pulse or logic command in an S-R latch circuit which is made up of a pair of NAND gates in a cross-connected configuration. The digital logic is arranged so that an output transistor and relay are energized only when the system senses the presence of the desired condition thereby indicating that it is safe to energize associated equipment.

Abstract: A sequencing and monitoring control device for fuel burners is provided having a unique burner program. The fuel burner is put into operation with an ignition means turned on, along with fuel pressure and combustion air, but without fuel being intentionally introduced into the combustion chamber. This start-up procedure would ignite any leakage fuel. The ignition is ended and an attempt is made to sense whether a flame exists thereby indicating the presence of leakage fuel. If any flame exists, the system shuts down on safety. If none exists, the sequence proceeds to a preselected burner sequence.

Abstract: A resistive fluid detecting means utilizes a probe means having three electrically conductive areas that are interconnected between a power source and an amplifier. The detecting means is particularly useful in detecting the presence or absence of water in a boiler used in a heating plant. The presence of water between two of the electrically conductive areas reduces the resistance of that path so that the amplifier responds and operates an output switch, which in turn can be used to energize a fuel burner for the boiler. If boiler scale builds up on the probe means or if the water or fluid rises too high, the electrically conductive areas shunt current away from the amplifier and allow the output switch to open.