Abstract: A power burner adaptable for use in conjunction with a wood burning stove employs a blower to produce a forced flow of air and a fuel valve which provides selective fuel communication with a fuel nozzle. Forced air and fuel is mixed in the nozzle and propelled through the nozzle outlet along a generally unidirectional exit path. A target is spaced from the nozzle outlet and interposed in the exit path. A heating assembly which is spaced from the target heats the target to a temperature sufficient to ignite the mixture traversing the exit path. A blast tube surrounds the target and forms an axially extending passageway which functions as a combustion chamber and a passageway for propelling the combusted fuel through an outlet opening of the blast tube. The burner is automatically controlled by an electronic controller.

Abstract: An improved electrical circuit for controlling the operation of a gas solenoid valve which regulates the flow of gas to a burner. Field effect transistors, whose operation is controlled by a flame rectification circuit and/or a timing circuit, directly control the operation of a relay which, in turn, operates the gas solenoid valve, thus eliminating the need for much more complicated circuitry to effect actuation of the gas solenoid valve.

Abstract: A direct ignition gas burner control system includes a microcomputer for controlling energizing of an electrical resistance igniter, for subsequently effecting flow of gas to the burner when the igniter is at gas ignition temperature, and for effecting continued flow of gas in response to current flow through the burner flame.

Abstract: Apparatus for monitoring flames is provided with means for sampling both the value of a flame and the period of time during which a flame remains above a given intensity level during start-up. Flame-off delay means is also provided in combination with means for delaying a flame-on indication, means for segregating the respective operations thereof, and means for maintaining the durations of the flame-on and flame-off delays in fixed proportional relationship.

Abstract: An improved system including a circuit for igniting a pilot burner each time heat is called for by a thermostat. The main burner is ignited by the standing pilot upon detection of pilot ignition. Trial ignition over a limited period of time is provided. Main and pilot oscillators each having only two transistors are employed to actuate respective main and pilot valves. Each oscillator is of a new type requiring few electronic components.

Abstract: An electronic ignition system for a gas burner is battery operated. The battery voltage is applied through a DC-DC chopper to a step-up transformer to charge a capacitor which provides the ignition spark. The step-up transformer has a significant leakage reactance in order to limit current flow from the battery during initial charging of the capacitor. A tank circuit at the input of the transformer returns magnetizing current resulting from the leakage reactance to the primary in succeeding cycles. An SCR in the output circuit is gated through a voltage divider which senses current flow through a flame. Once the flame is sensed, further sparks are precluded. The same flame sensor enables a thermopile driven main valve actuating circuit. A safety valve in series with the main gas valve responds to a control pressure thermostatically applied through a diaphragm. The valve closes after a predetermined delay determined by a time delay orifice if the pilot gas is not ignited.

Abstract: In a digital control circuit, a clock pulse is counted so that when a predetermined timing is reached the driving of a load is controlled. The digital control circuit may preferably be an integrated circuit for controlling the combustion of a burner for a combustion apparatus such as a water heater or an air heater. The combustion control circuit performs the igniting operation for a predetermined period of time and the supply of fuel is stopped if the ignition can not be attained within the predetermined period.

Abstract: An ignition system for a furnace or boiler where a predetermined number of firing pulses are generated between timing intervals to allow purging of the combustion chamber. If combustion occurs, the firing pulses are terminated. If combustion does not occur, after the predetermined number of firing pulses, the combustion chamber is purged and the system shut down.

Abstract: A fuel burner control system including a valve for controlling the flow of fuel to a burner, a resistive heater element for igniting fuel, a power supply for supplying current to the heater element, a flame sensing circuit comprising an ac source for supplying ac voltage to the heater element, and a detector for producing an output signal only in response to the flow through the heating element of current rectified by the flame, a valve control circuit for maintaining the valve open in response to the output signal, and a coupling circuit interconnecting the heating element with both the power supply and the sensing circuit and adapted to prevent the flow of current therebetween. By utilizing a coupling circuit that prevents the flow of current between the power supply and the flame sensing circuit, the resistive heater element can be efficiently and alternately used both as a fuel igniting mechanism and as an electrode for deriving current rectified by flame at the burner.

Abstract: A purge time hold circuit is provided in a flame safeguard sequencer to in turn provide a safe start check of a burner control system. If a flame is indicated during a prepurge period, the purge time hold means will reset to a zero status and the timer will hold until the signal clears itself. If the flame signal does not clear itself within a preset time, a safety shut down will be commanded.

Abstract: A combustion control apparatus in which a predetermined number of pre-purge and igniting cycles are repeated until ignition takes place successfully. A pre-purge time interval of the second and subsequent igniting cycles is selected shorter than that of the first igniting cycle. When an existing combustion control element which is capable of performing the igniting cycle only once is employed, the intended combustion control is performed by appropriately controlling a reset terminal of the existing combustion control element of signals representative of expirations of the pre-purge time interval and the ignition time interval. The number of the igniting cycles is counted by a counter for stopping operation of the combustion apparatus when a predetermined count value is attained. A novel circuit for the combustion control element is also disclosed.

Abstract: An oil burner primary control in an interrupted ignition burner control system includes a regulating circuit for regulating the voltage across a flame-responsive photo-conductive cell. The regulating circuit ensures that, in the event the cell becomes defective so as to exhibit abnormal resistance characteristics, the system will not permit fuel to flow unless a burner flame exists or unless the igniter and a safety circuit are energized.

Abstract: A combustion control apparatus which controls combustion in a combustor which is a heat source of a hot-water boiler or a hot-air heater includes a memory circuit which generates an alarm signal and also a signal for stopping the operation of the apparatus and which maintains the apparatus in the shutdown state, when an abnormal condition such as abnormal heating or ignition failure is sensed. This memory circuit is protected from malfunction due to noise generated from external output units in the combustion control apparatus by a circuit which detects an abnormality signal with timing other than the timing of generation of noise from the external output units, and the output of this circuit is applied as an input to the memory circuit. The detection circuit is arranged to detect the abnormality signal while receiving clock pulses from a timer as its input, and the phase of its detection timing is selected to be out of phase with the noise generation.

Abstract: An intermittent gas pilot system utilizing a flame signal simulating circuit means provides for both dynamic as well as static safe start checking for the system. A simulated flame signal is provided so that the relays contained within the system must be checked dynamically before the system will allow the opening of the main gas valve.

Abstract: An integrated, microprocessor-based primary control system for a building heating system. The control system includes in one unit a microprocessor and associated circuitry for (1) establishing the high limit of heat exchanger operation, (2) establishing the low-limit of heat exchanger operation for systems having a summer/winter coil, (3) modulating heat exchanger temperature as a function of outdoor temperature, (4) detecting alarm conditions, providing audio-visual signals while locking out heat exchanger operation in response thereto, and (5) providing an override time period for domestic hot water production in systems having a summer/winter coil.

Abstract: A flame detection and proof device utilizing NAND logic implemented by MNOS devices which provides safe control of gas systems and appliances. Improved control is achieved by using a flame probe for providing signals indicative of flame and no-flame conditions connected to circuit means which includes at least one delay circuit for producing a first output signal during a set time period for ignition and also during indication of a flame condition and a second output signal after the set time period and during an indication of no-flame condition. A relay is responsive to the output of the circuit means to be activated during the first output signal and to be deactivated during the second output signal.

Abstract: A fuel burner control system including a valve for controlling the flow of fuel to a burner, a resistive heater element for igniting fuel, a power supply for supplying current to the heater element, a flame sensing circuit comprising an ac source for supplying ac voltage to the heater element, and a detector for producing an output signal only in response to the flow through the heating element of current rectified by the flame, a valve control circuit for maintaining the valve open in response to the output signal, and a coupling circuit interconnecting the heating element with both the power supply and the sensing circuit and adapted to prevent the flow of current therebetween. By utilizing a coupling circuit that prevents the flow of current between the power supply and the flame sensing circuit, the resistive heater element can be efficiently and alternately used both as a fuel igniting mechanism and as an electrode for deriving current rectified by flame at the burner.

Abstract: An arrangement for a direct ignition type fuel ignition system includes a capacitive timing network which enables a flame relay to operate during a trial for ignition interval, energizing a fuel valve to supply fuel to a burner for ignition, and a flame sensing circuit which causes the flame relay and the fuel valve to be maintained operated only if a flame is sensed before the end of the trial for ignition interval. In the absence of a flame, a diode, back biased by the timing signal, decouples the flame sensing circuit from the timing network. When a flame is established, a further diode, back biased by a control signal provided by the flame sensing circuit, decouples the timing network from the flame sensing circuit. In an embodiment wherein the charging time of a capacitor defines the trial for ignition interval, a fast reset circuit provides rapid discharge of the timing capacitor when power is removed from the timing network.

Abstract: An electronic control system for safely operating a pair of redundant solenoid type valves is disclosed. The system utilizes an alternating current potential for energizing the valves. The first valve is energized across the applied potential and then is placed in series with the second valve. The series combination is selected so that once the valves are energized they will stay energized in the series configuration.

Abstract: A safety ignition valve for a pilotless burner comprises a valve body having an inlet for connection to a fuel supply, an outlet for connection to the burner and a valve seat between the inlet and outlet. A valve member is movable between a closed position in which it is seated on the valve seat and an open position in which it is spaced from the valve seat. A spring acting on the valve member biases it toward closed position. A first solenoid which is energized by current produced by a thermocouple heated by the burner acts on the valve member to hold it in open position against the bias of the spring. A second spring solenoid located in a control box fixed to the valve body actuates a plunger for moving the valve member to open position when the second solenoid is energized.

Abstract: A control arrangement for a direct ignition type fuel ignition system including a timing circuit having a timing capacitor which charges in response to application of power to the system defining a trial for ignition interval during which a controlled switching device is enabled to operate a flame relay to energize a fuel valve to supply fuel to a burner for ignition by sparks provided by a spark generator, the controlled switching device being disabled, deenergizing the flame relay when the timing capacitor becomes fully charged before the fuel is ignited, and the controlled switching device being maintained enabled through the action of a flame sensing circuit which is coupled to the timing circuit only when a flame is established.

Abstract: Safety ignition means for burner installations having a solenoid of a solenoid operated valve connected to a power source through a normally opened relay switch. The relay switch has a hold coil connected to the power source and a make coil connected to the power source through a flame switch which operates, when the flame switch is heated by the flame of the pilot burner, to energize a solenoid of a solenoid operated valve for main burner and de-energize the make coil. A normally closed bimetal switch is connected between a power supply and the safety ignition means and has a heat source connected in series with the make coil. If the pilot burner is not ignited for a predetermined period of time, the heat source heats the bimetal switch so that the bimetal switch is opened to separate the ignition means from the power supply.

Abstract: A control circuit for use with spark ignition system disposed in a gas burner comprising a high voltage pulse circuit for developing the spark which is gated by a flame sensor. That same flame sensor also controls a timing and latch circuit connected to initially open the gas flow to the burner and to close such gas flow if burning is not established within a predetermined interval of time. The timing and latch circuit also includes components which after an unsuccessful start-up preclude further starting cycles until manual intervention takes place and control all failure modes to a shut-down condition.

Abstract: A gas burner control system including a main burner and a pilot burner for igniting the main burner wherein the pilot burner is ignited only when the thermostat is calling for heat and wherein a normally closed bimetal operated safety switch is effective to provide a trial ignition period for igniting the pilot burner. An electrical resistance heater for effecting opening of the safety switch is in the gate cicuit of a solid-state switch and is energized in the absence of pilot burner flame. The solid-state switch, when conducting, is effective to complete an electrical circuit through the safety switch to open a first valve and initiate gas flow to the pilot burner. When pilot burner flame exists, the resistance heater is de-energized, the first valve is held open by means including a switch responsive to gas pressure downstream from the first valve, and a second valve, fluidically in the series with the first valve and controlling the flow of gas to the main burner, is opened.

Abstract: A system for trial period ignition of a fluid fuel burner having an oscillator with a gate in the feedback path thereof, the oscillator providing power to a burner fuel valve and to a spark generator, wherein oscillator operation is sustained after the period only upon flame detection which keeps the oscillator feedback path gate closed.

Abstract: The primary side of the burner control circuit, which has as its primary function the application of a line voltage to the burner motor and igniter, includes: a triac switch for applying the line voltage to the burner motor and igniter; in response to a first optical coupler; a circuit breaker switch for disconnecting the primary from the line voltage; and a light source for a second optical coupler. The secondary side of the burner control circuit, which is responsive to a thermostat, includes: a light sensitive element for detecting a flame at the burner; a light source for the first optical coupler; and a current responsive element which in combination with the circuit breaking switch in the primary functions as a circuit breaker.