Abstract: A control circuit for a fuel ignition system of the direct ignition type for providing an interlock on start-up to prevent the energization of a fuel supply valve of the system under certain failure conditions includes an interlock relay which is energized, after a predetermined delay, over normally closed contacts of a flame relay to control a timing network to cause a flame sensing circuit to enable the flame relay to energize the valve during a trial for ignition interval defined by the timing network, the flame sensing circuit maintaining the flame relay, and thus the valve, energized when a flame is provided during the trial for ignition interval, the energization of the valve and the interlock relay being prevented if the normally closed contacts of the flame relay are open on start-up, and the delayed operation of the interlock relay preventing lockout of the system following momentary loss of power.

Abstract: A self-checking fuel ignition system of the pilot ignition type including a sampling flame sensor which effects periodic testing of the operability of a spark generating circuit to provide ignition sparks, and an energizing circuit which operates independently of the spark generating circuit but under the control of the flame sensor, to control the operation of fuel valves of the system and to effect the shut down of the system for loss of flame or ignition spark.

Abstract: A control arrangement for a heating system including a furnace having a fuel-fired burner apparatus and a vent stack with a motor driven damper plate for opening and closing the stack, includes an interlock switch which provides a safety interlock between fuel supply valves of the system and first and second limit switches which control the energization of a drive motor for the damper plate and effect energization of the fuel supply valves of the system, permitting the fuel valves to operate only when the damper plate is in the open position and preventing energization of the fuel valves in the event of a malfunction of either of the limit switches. The interlock switch also permits recycling of the system in the event of a momentary power interruption. The control arrangement may include a stack mounted heat sensor switch which interrupts the energizing path for the fuel supply valves in the absence of heat from the main burner within a predetermined interval of time.

Abstract: A gas valve having first and second redundant valve members, disposed in a passageway between an inlet and an outlet of the valve which are individually operable to open and close respective inlet and outlet valve ports, and a pressure regulating apparatus interposed between the inlet and outlet valve ports operable to supply gas to the outlet valve port initially at a pressure lower than the inlet pressure when the first and second valve members are operated to open respective valve ports, and to gradually increase the pressure of the gas supplied to the outlet valve port until the outlet pressure equals a value intermediate the inlet pressure and the initial outlet pressure, as established by a pressure regulator spring of the pressure regulating apparatus. The gas valve is disclosed with reference to an application in a fuel ignition system to regulate gas flow to a combustion box to minimize ignition noise and rollout of gas flame from the combustion box.

Abstract: A control arrangement for a fuel ignition system including redundant pilot and main valves, includes a thermal heat sensor mounted on a heat exchanger or in an exhaust stack of main burner apparatus and having a heating element which is energized in response to operation of thermostatically controlled contacts to close associated contacts to effect energization of the pilot valve permitting fuel to be supplied to a pilot outlet and the main valve which is operated when a pilot flame is established, the heating element being deenergized when the main valve is operated and the heat sensor being responsive to heat from the main burner to maintain the contacts closed maintaining the pilot valve energized. The heat sensor responds to a flame out condition to deenergize the pilot valve, thereby interrupting fuel flow to main valve.

Abstract: A control arrangement for a heating system including a furnace having a fuel-fired burner apparatus and a vent stack with a motor driven damper plate pivotally mounted within the stack, includes a stack damper control circuit including first and second limit switches which permit energization of a drive motor in response to a request for heat, premitting the damper plate to be driven to an open position, and for energizing an interlock switch which prepares an energizing path for fuel supply valves of the system, the first limit switch being operated when the damper plate approaches the open position to complete the energizing path for the fuel supply valves prepared by the interlock switch, and the second limit switch deenergizing the motor when the damper plate is driven to the fully open position. The motor is reenergized at the end of the heating cycle to drive the damper plate to the closed position, and the second limit switch deenergizes the motor when the damper plate reaches the closed position.

Abstract: A control arrangement for a fuel ignition system for providing an interlock on start-up to prevent the energization of fuel valves of the system under certain failure conditions includes a switching device which is energized over normally closed contacts of a flame relay to close associated contacts to prepare an energizing path for a pilot valve and to energize an interlock relay which completes the energizing path for the pilot valve, a main valve being energized and the switching device being deenergized to interrupt the energizing path when the flame relay is operated in response to the establishing of a pilot flame, and the pilot valve and the main valve being maintained energized over a holding path provided by the interlock relay, the energization of the pilot valve and the interlock relay being prevented whenever the normally closed contacts of the flame relay are open on start-up.

Abstract: A control arrangement for use in an automatic fuel ignition system for providing electronic detection of a leak condition for a pilot valve operable to supply fuel to a pilot outlet for ignition to establish pilot flame includes a flame sensing circuit which effects operation of a main valve when a pilot flame is established, the flame sensing circuit maintaining the main valve deenergized when a pilot flame is established during an ignition interval and permitting a delay device to deenergize the pilot valve for a time to interrupt the supply of fuel to the pilot outlet to attempt to extinguish the pilot flame, and a time out device operable to deactivate the system when the delay device fails to cause the pilot flame to be extinguished, the flame sensing means overriding the delay device and the timeout device when the pilot flame is established at the end of the ignition interval.

Abstract: A gas valve having first and second redundant valve members, disposed in a passageway between an inlet and an outlet of the valve which are individually operable to open and close respective inlet and outlet valve ports, and a pressure regulating apparatus interposed between the inlet and outlet valve ports operable to supply gas to the outlet valve port initially at a pressure lower than the inlet pressure when the first and second valve members are operated to open respective valve ports, and to gradually increase the pressure of the gas supplied to the outlet valve port until the outlet pressure equals a value intermediate the inlet pressure and the initial outlet pressure, as established by a pressure regulator spring of the pressure regulating apparatus. The gas valve is disclosed with reference to an application in a fuel ignition system to regulate gas flow to a combustion box to minimize ignition noise and rollout of gas flame from the combustion box.

Abstract: A fail-safe energizing circuit for effecting the operation of a functional device, such as a relay, includes a resistor and a capacitor connected between outputs of an AC signal source which supplies an AC signal for charging the capacitor, a normally disabled silicon controlled rectifier connected in shunt with the capacitor and an operate coil of the relay and operable when enabled to provide a discharge path for the capacitor permitting the capacitor to discharge over the relay coil to operate the relay, and a control circuit operable to provide an enabling signal derived from the AC signal for enabling the silicon controlled rectifier. The energizing circuit is described with reference to an application in an automatic fuel ignition system for controlling the operation of a relay which energizes a fuel valve of the system.

Abstract: An automatic fuel ignition system which provides automatic detection of a leak condition for a pilot valve which is operable to supply fuel to a pilot burner for ignition to establish pilot flame and a main valve which is operable to supply fuel to a main burner for ignition by the pilot flame of the system including a control circuit operable in response to a request signal to activate the system tentatively, a delay circuit which delays the operation of the pilot valve for a first delay period after the occurrence of the request signal, a flame sensing circuit which senses the presence of the pilot flame and effects operation of the main valve after a second delay period established by the control circuit, the flame sensing circuit being responsive to the presence of a flame at the pilot burner during the first delay period or at the main burner during the second delay period to cause the system to be deactivated.

Abstract: A valve assembly including a gas valve having first and second redundant valve members which are individually operable to open and close respective inlet and outlet valve ports, and a pressure regulating apparatus interposed between the inlet and outlet valve ports operable to control gas flow to the outlet valve port when the first and second valve members are operated, and a leak detection apparatus for detecting a leak across one of the valve ports, including a pressure diaphragm operated valve which is maintained open responsive to gas flow through both the valve inlet port and the valve outlet port to permit gas flow to an outlet of the valve, the valve being operated to close in the event of gas flow for a predetermined time through only one of the ports indicative of a leak condition for the port.

Abstract: A pilot fuel ignition system including an ignition circuit for generating sparks for igniting fuel emanating from a pilot burner to establish a pilot flame, a control circuit responsive to the ignition circuit to operate a pilot valve to supply fuel to the pilot burner, and a sampling circuit controlled by the control circuit to maintain the pilot valve operated and to operate a main burner valve to supply fuel to a main burner for ignition by the pilot flame. A flame sensing circuit enabled whenever a pilot flame is established normally disables the ignition circuit, but periodically enables the ignition circuit to test the operability of the ignition circuit. Failure of the ignition circuit to operate results in the disabling of the sampling circuit causing shutoff of the pilot and main burner valves. Also, a warp switch energized whenever the pilot flame is extinguished effects shutoff of the pilot valve interrupting the supply of fuel to the pilot and the main burners.