Abstract: This invention relates to a control and safety circuit (1) for gas delivery valves, comprising an actuator (50) opening the gas delivery valve; a control unit (100) intended to emit a command signal (V2) to activate the actuator and switch on the valve, and a clock signal (CK); and a memory (5) placed between the control unit (100) and the actuator (50). The memory is capable of receiving the command signal (V2) and the clock signal (CK) as inputs, and at the same time emits an output signal (V3) which is a function of the input command signal (V2) and a clock signal (CK). The output signal (V3) is sent to the actuator (50) to command the same to open the valve.

Abstract: A heater for a liquid has a combustion chamber, a jacket for the liquid extending about the combustion chamber and a burner head assembly connected to the combustion chamber. The burner head assembly includes a housing having a burner mounted thereon and a hollow interior. A control module and a fan are mounted in the hollow interior, the fan being connected to an electric motor. A compressor and a fuel pump are mounted on the housing and are operatively connected to the electric motor. The control module may include controls for exercising components of the heater prior to combustion, thereby verifying operation of these components. Preferably there is a speed control for the motor, such as a closed loop speed control which regulates motor speed and accordingly output of the heater. Preferably there is a backup system using a lookup table in the event that the closed loop speed control fails.

Abstract: A system for providing a combined water and fire display is provided. More specifically, a decorative display comprises a dynamic water and fire display device where fuel/air, water, and fire are integrated. The decorative display provides for unique aesthetic qualities and an appearance wherein flames are positioned at or near the surface of a volume of water. In various embodiments, the decorative display further comprises various safety features including the ability to detect and self-regulate conditions such as the existence and/or absence of a pilot flame, an adequate amount of water, and the temperature of various portions of the system. The decorative display further contemplates the ability to operate without one or more disclosed features, such as when only a water display or only a fire display is desired.

Abstract: An adaptive gaseous fuel ignition control method for use in consumer and commercial appliances that reduces stress on and increases the life of a hot surface igniter without resulting in a failure to ignite condition is provided. The method provides a preheating period, a full temperature period, and a trial for ignition period. The preheating period gradually increases the power applied to reduce the stress resulting therefrom. Once a gas valve has been commanded open, the controller monitors the time for ignition of the gaseous fuel. If the time is longer than a threshold, either the applied power or the period of time during which the power is applied is increased to shorten the time. If, however, the ignition period is shorter than the threshold, either the power applied or the period of time during which the power is applied before commanding the gas valve open is lowered or shortened.

Abstract: A cooking appliance a gas burner configured to generate a quantity of heat is disclosed. The cooking appliance also includes a pressure sensor operable to measure the pressure of gas supplied to the gas burner from a gas control valve. The gas control valve is operable to adjust the supply of gas to the gas burner based on the measured pressure of the gas.

Abstract: A flame-emitting apparatus is provided, whereby a burner has an inlet connected to a fuel source. Fuel burned by the burner provides a flame extending from an outlet of the burner. A flame ignition system detects the presence of the flame during operation of the apparatus and controls supply of fuel to the burner in response to flame detection.

Abstract: A gas burner ignition system, includes a power circuit (1), igniter (3), a solenoid valve (6); an igniter switch control circuit (2) which is connected between the power circuit (1) and igniter (3); a solenoid valve switch control circuit (5) connected between the power circuit (1) and the solenoid valve (6); the solenoid valve switch control circuit (5) and the igniter switch control circuit (2) are responsive to delay circuit (4), so that the user need only operate the control knob without the need to hold the operating knob until the thermocouple (42) has reached operating temperature.

Abstract: An ignitor spark indicator 100 is described that monitors RF signals within a flame rod 25 located near a spark rod 23. The signal from the flame rod 25 is processed to provide a waveform that indicates when electrical arcing is occurring. The indication when arcing is occurring is also provided to flame-detecting equipment. The flame-proving device 60 only operates when the arcing is not produced so that the flame-detecting device 60 does not confuse the arcing with a flame reducing the false positive determinations.

Abstract: A self validating flame detection system (10) for a turbine engine (12) configured to determine whether a flame exists in a turbine engine combustor is disclosed. The self validating flame detection system (10) may include two different types of flame detection sensors to reduce the risk of false positive signals. In at least one embodiment, the flame detection system (10) may include one or more infrared sensors (20) that sense infrared radiation within the combustor of the turbine engine (12) and one or more ultraviolet light sensors (22) that sense ultraviolet light within the combustor of the turbine engine (12). The flame detection system (10) may include a processor (24) configured to ignore the steady state infrared signal generated and instead analyze the dynamic infrared signal. The processor (24) may be configured to determine whether both types of sensors indicate a flame out condition so that a false alarm does not occur.

Abstract: A cooking appliance having a gas burner operable to generate a quantity of heat is disclosed. The cooking appliance also includes a pressure sensor operable to measure the pressure of gas supplied to the gas burner from a gas valve. The gas valve is programmed to adjust the supply of gas to the gas burner based on the measured pressure of the gas.

Abstract: A rapid recovery tankless water heater operates by means of an electronic controller or card that regulates the operation of each of the system components, thereby optimizing gas consumption and minimizing the emission of gas pollutants. A multi-burner only ignites when certain conditions or predefined requirements in the electronic controller logic are met. Other factors contributing to improved water heater efficiency are: a) the water tank design which at the bottom has a water chamber surrounding the combustion chamber, and b) the use of a finned heat exchanger, which together with a core, successfully utilizes most of the thermal energy contained in the combustion gases. An air deflector device stops the entry of air currents at the top of the heater, thus stopping potential flame reversing and even flame extinction in the multi-burner.

Abstract: A cooking appliance having a gas burner operable to generate a quantity of heat is disclosed. The cooking appliance also includes a pressure sensor operable to measure the pressure of gas supplied to the gas burner from a gas valve. The gas valve is programmed to adjust the supply of gas to the gas burner based on the measured pressure of the gas.

Abstract: A system for providing a combined water and fire display is provided. More specifically, a decorative display comprises a dynamic water and fire display device where fuel/air, water, and fire are integrated. The decorative display provides for unique aesthetic qualities and an appearance wherein flames are positioned at or near the surface of a volume of water. In various embodiments, the decorative display further comprises various safety features including the ability to detect and self-regulate conditions such as the existence and/or absence of a pilot flame, an adequate amount of water, and the temperature of various portions of the system. The decorative display further contemplates the ability to operate without one or more disclosed features, such as when only a water display or only a fire display is desired.

Abstract: Disclosed herein is a method of controlling a gas type clothes dryer. The method control the dryer to continuously detect condition of a flame sensor even after ignition of the dryer, thereby preventing a drying operation from being performed when a flame has been extinguished due to insufficient gas supply caused by failure of a gas valve.

Abstract: The aim of the invention is to create a gas regulating fitting which, once a gas stove has been successfully started up, can switch the pilot burner into the off position when the main burner is in the off position, in order to maintain the power consumption of the gas stove as low as possible. The aim of the invention is also to provide the gas regulating fitting with as simple a structure as possible. To this end, the gas regulating fitting comprises a sensor (34) by which means the operating state of the main burner (33) can be detected. The sensor (34) is connected to a thermoelectric safety pilot valve (17) in such a way that, when the operating state of the main burner (33) is switched from the on position into the off position by a signal emitted from the sensor (34), the thermoelectric safety pilot valve (17) assumes the closed position thereof. The gas regulating fitting can be used to ignite and to regulate a gas flow flowing to a burner.

Abstract: A fuel burner controller and associated method is configured to establish fuel combustion in a fuel burner and to recycle a fuel combustion initiation process when a loss of combustion is detected and a call for heat is asserted. The controller is further configured to limit a number of recycles of the fuel combustion initiation process based on a time budget.

Abstract: An adaptive gaseous fuel ignition control method for use in consumer and commercial appliances that reduces stress on and increases the life of a hot surface igniter without resulting in a failure to ignite condition is provided. The method provides a preheating period, a full temperature period, and a trial for ignition period. The preheating period gradually increases the power applied to reduce the stress resulting therefrom. Once a gas valve has been commanded open, the controller monitors the time for ignition of the gaseous fuel. If the time is longer than a threshold, either the applied power or the period of time during which the power is applied is increased to shorten the time. If, however, the ignition period is shorter than the threshold, either the power applied or the period of time during which the power is applied before commanding the gas valve open is lowered or shortened.

Abstract: A battery powered ignition and control system for a gas burner includes circuits for controlling a pilot burner, a main burner, a flame sensor and an igniter. Mechanically latched valves, which require power only to switch between and open and closed state are used to control the pilot and main gas. The circuitry spends a majority of time in a powered down state and draws power only when required to interrogate the state of the flame and to perform an ignition sequence as required, as periodically dictated by a watchdog system. The latching valves are electrically pulsed to change state and thus draw very low average power when called upon. Lithium batteries provide system power for a long duration.

Abstract: A flame sensor apparatus for use with a flame heated thermal abatement reactor is provided, including a flame sensor adapted to sense a flame within the thermal abatement reactor; and a shutter adapted to selectively block the transmission of radiation from the flame to the flame sensor.

Abstract: Techniques for monitoring operation of a flame ignitor are provided. In one embodiment, multiple inputs are received. The inputs are received from at least one of a first group of inputs and a second group of inputs. The first group includes a flame rod voltage, a stop signal for deactivation of the flame ignitor, a fuel supply interruption signal, and an air supply interruption signal. The second group includes a start signal for activation of the flame ignitor, and a flame proven signal indicating presence of a flame produced by the flame ignitor. If inputs from the first group are received, a cause of a failure of the flame ignitor is determined. If inputs from the second group are received, a reliability of the flame ignitor is determined.

Abstract: A method for a security control of a burner, provided with a body comprising a diffuser in which apertures for the flow of a mixture of air and fuel are made, comprises detecting a temperature representative of the temperature of said diffuser in at least one zone of the diffuser, generating a signal having an intensity depending on said representative temperature.

Abstract: A gas lamp system and method for lighting the system which utilizes a sparkless flame starter in close proximity to the torch to create a flame. The system further includes a safety control circuit which activates the sparkless flame starter and subsequently actives a gas valve to deliver the gas to the torch after the sparkless flame starter has been energized. The sparkless flame starter is a low-voltage device such as a glow coil which is also arcless.

Abstract: A communication and data interpreting system for detecting and converting and combining multiple analog signals from flame detectors into a single analog signal and RS 485 for transmission. This system also uses an analog clamping circuit to generate the analog signal from flame rod sensors and a load resistor and a high voltage generator for generating the signal in an UV sensing tube. The input signals are then multiplexed and sent to a microcomputer. The microcomputer uses a diode and a solid state relay circuit to generate a compatible signal output to a burner control.

Abstract: A method for a security control of a burner, provided with a body (1) comprising a diffuser (2; 8) in which apertures (3) for the flow of a mixture of air and fuel are made, comprises detecting a temperature representative of the temperature of said diffuser in at least one zone of the diffuser, generating a signal having an intensity depending on said representative temperature.

Abstract: A stove burner safety system has an electromagnetic valve and a manual gas cock controlling the gas flow to the burner and a spark plug adjacent the burner which receives a spark pulse from the electric circuitry which also controls an electromagnetic valve. When the stem of the manual valve is actuated a switch turns on the electric module and when a flame failure is detected a train of a certain number of spark pulses is supplied to the spark plug and if reignition does not occur within a certain number of pulse or a certain time, the electromagnetic valve is turned off.

Abstract: A method and a system for igniting a gas burner of a gas stove is disclosed, which includes a spark generating circuit to produce sparks for igniting gas burners and a plurality of electrodes which are connected with the spark generating circuit for the ignition of the gas burners. A flame sensor circuit is operated in a first period for producing sparks, through of the electrodes, and in a second period and once the gas burner has been ignited, for sensing the presence of flame on each gas burner. A power source is connected for limiting the voltage to the flame sensor circuit.

Abstract: A fuel oil burner utilizing a hot surface ignition with an ignitor that is fully sintered and has essentially no porosity, a voltage phase regulator circuit for applying rectified half-wave AC line voltage, full-wave rectified AC, or either half-wave or full-wave rectified AC line voltage to the ignitor to supply power thereto, and AC line voltage to a blower motor, an AC-to-DC converter, a DC voltage preregulator, and a DC voltage regulator for providing twelve volts DC for operation of a control circuit that has a first time constant circuit for preheating the ignitor and maintaining the ignitor at consistent ignition temperature for a predetermined ignition trial time period and a second time constant circuit for driving second and third motor drive circuits.

Abstract: A gas appliance is provided for producing an open flame. The gas appliance includes an elongated gas tube, a gas inlet, a nozzle, a flame sensor, a gas shut-off valve, and a protective member. The gas tube has a proximal end and a distal end. The gas inlet is located near the proximal end, for connection to a source of combustible gas. The nozzle is located at the distal end, for expelling the combustible gas to produce the open flame. The flame sensor detects the open flame and communicates its absence or presence to the gas shut-off valve. The gas shut-off valve has a valve inlet, a valve outlet, a control input, and the over-ride mechanism. The valve inlet is connected to the gas inlet. The valve outlet is connected to the proximal end of the elongated gas tube.

Abstract: An apparatus for drying a moving substrate containing a multiplicity of infrared emitters and a detection emitter and a device for supplying a mixture of air and gas to these emitters. The detection emitter contains an emitter body with a diffuser for distributing a fuel-oxygen containing gas mixture, a primary radiator having a combustion surface integrally connected to the emitter body, a first detection electrode, and a second detection electrode; each of these detection electrodes sends a signal to a control means when it senses the presence of flame-induced ionization. If the control means receives a signal from one but not both of these detection electrodes, it will continue supplying the air/gas mixture to the emitters. However, only when the control means ceases receiving a signal from both of the detection electrodes will it ceases allowing the supply of the air/gas mixture to the emitters.

Abstract: A gas burner system including a burner body having a flange providing an annular surface. A removable cap is disposed above the burner body and contacts the annular surface for forming an annular interface with the burner body for closing the burner body. A plurality of ports are provided along the annular interface between the burner body and the cap. A first ignitor is disposed adjacent the annular interface between the burner body and cap. A second ignitor is also disposed adjacent the annular interface between the burned body and cap. Electronic means energize the first and second ignitors for generating sparks to ignite the gas burner. The energizing means include means for sensing the presence of flame at both the first and second ignitors such that during burner operation, if no flame is sensed at both the first and second ignitors, the ignitors are energized for generating sparks.

Abstract: A method for controlling an igniting operation for a gas boiler for preventing an explosive ignition is disclosed. The gas boiler is equipped with a burner for burning a gas, a fan for exhausting a burnt gas in the burner, and an ignition plug for performing igniting operation of the gas supplied into the burner. If the operation of the gas boiler commences, the gas is supplied into the burner while the exhaust fan is operated at a low speed appropriate for performing the igniting operation, and the ignition plug is operated to perform the igniting operation of the gas in the burner. In that situation, if ignition does not occur during a predetermined time, the rotational velocity of the exhaust fan increases, whereby the density of gas in the burner is maintained constant. Thus, the excessive increasing of the gas density is prevented, so the explosive ignition is prevented.

Abstract: A fuel oil burner utilizing a hot surface ignition with an ignitor that is fully sintered and has essentially no porosity, a voltage phase regulator circuit for applying rectified half-wave AC line voltage, full-wave rectified AC, or either half-wave or full-wave rectified AC line voltage to the ignitor to supply power thereto, and AC line voltage to a blower motor, an AC-to-DC converter, a DC voltage preregulator, and a DC voltage regulator for providing twelve volts DC for operation of a control circuit that has a first time constant circuit for preheating the ignitor and maintaining the ignitor at consistent ignition temperature for a predetermined ignition trial time period and a second time constant circuit for driving second and third motor drive circuits.

Abstract: A gas burning power supply section 10 for igniting gas includes a secondary battery and a solar battery for charging the secondary battery, and the operating voltage from the power supply section 10 is supplied to a gas ignition circuit 30, a flame detection circuit 50 for detecting the flame after the gas is ignited, and a solenoid valve-controlling timer circuit 60 for controlling the gas supply. A day/night discrimination circuit 100 is provided in association with the power supply section 10, and the ignition circuit 30, the flame detection circuit 50 and the timer circuit 60 are individually set in operation in accordance with a day/night discrimination output during the nighttime. In the event the flame of burning gas goes out halfway, the timer circuit 60 operates to perform a trial including reigniting operation, and if the reigniting fails during a trial period, the gas supply is automatically shut off.

Abstract: A fuel oil burner utilizing a hot surface ignition with an ignitor that is fully sintered and has essentially no porosity, a circuit for applying AC line voltage to the ignitor and to a blower motor, an AC-to-DC converter for providing twelve volts DC for operation of a control circuit that has a first time constant circuit for preheating the ignitor and maintaining the ignitor at an ignition temperature for a predetermined ignition trial period of time, a second time constant circuit for starting the blower motor and providing fuel to the combustion chamber for a predetermined time concurrent with the ignition trial period, and a third time constant circuit that either maintains the fan blower in its energized state if a flame of sufficient magnitude and frequency is detected and for de-energizing the blower motor if the flame is not detected in less than one second after the ignitor is de-energized.

Abstract: A fuel valve and ignitor control system in which pull-in current for a fuel valve operating on rectified alternating current is supplied through a first normally open relay whose coil is connected in series with normally open contacts of a second relay and an intermittently operating hot surface ignitor. Normally closed contacts of the second relay are connected in series with the ignitor and the fuel valve through a holding resistor, whereby actuation of the second relay provides unrectified alternating current to the ignitor and actuates the first relay to provide pull-in current to the fuel valve, and whereby deactivation of the second relay provides holding current to the fuel valve through the ignitor.

Abstract: A gas burning fireplace having a burner for producing a flame. A rod in the vicinity of the burner. A gap between the burner and the rod and wherein a flame is produced in the gap. An apparatus for monitoring the presence of a flame including a battery for applying a DC voltage between the rod and the burner. An electric circuit means for sensing a DC current between the rod and the burner.

Abstract: A safety device for gas-fired equipment having a main gas supply control valve and a plurality of gas-taps each associated with a flame-producing burner. The device includes a plurality of switches each associated with a gas-tap and actuatable by the operation of the gas-tap, a plurality of heat responsive sensors each having a switching circuit operationally connected in circuit with a secondary control circuit and a timer, and a central control unit connected in circuit for receiving control signals from the output of each of the secondary control circuits, thereby controlling the state of the main gas supply valve. Upon the detection by a heat responsive sensor of the extinction of a fire from a burner when a gas-tap associated therewith is open, after a predetermined time period, the secondary control circuit connected to the sensor emits a signal to the central control unit for effecting the closing of the main gas supply valve.

Abstract: A gas valve control system including a microprocessor, a first relay, a second relay, flame sensor and a timer. The timer is connected to the switch which is connected in the power supply path of the second relay. The second relay is connected to the valve. Activation of the first relay causes activation of the second relay causing the valve to open. Also, activation of the first relay causes the timer to operate. The flame sensors then must sense flame or else the microprocessor will deactivate the first relay. If the microprocessor fails to deactivate the first relay, the timer causes the switch to open and break the power supply path to the second relay. This in turn causes the valve to close.

Abstract: A hot surface ignition system for a gas furnace or the like, control device therefor and methods of making the same are provided, the system comprising a burner, a settable thermostat, an electrically operable gas valve, a control unit, and an electrically operable hot surface igniter disposed so as to be in the path of gas issuing from the burner that is adapted to be fed the gas from a source thereof through the gas valve when the control unit has been activated by the thermostat to operate the igniter and the gas valve in a certain sequence, the control unit having a lockout unit for deactivating the system should ignition of the gas issuing from the burner not take place by the end of the certain sequence, the control unit having a resetting unit for causing the control unit to be reactivated to be adapted to repeat the certain sequence of the system when the resetting unit is activated, the control unit being adapted to select the certain sequence to have one or more attempts of the control unit to ignit

Abstract: The presence of a flame from a burner is determined by analyzing the signal produced by a radiation sensor aimed at a burner. Specifically, a Fourier transformation is applied to the signal producing amplitude values for a spectrum of component frequencies produced by changes in the power of the flame over time. A logarithmic value is derived for each of the amplitude values. The degree of linearity of the distribution of the component frequency logarithmic amplitude values provides an indication of the flame presence. Several parameters, including integrated linear error, linearity regression correlation and slope difference, provide an indication of the degree of linearity. A plurality of values for each of these parameters are produced during an interval of time.

Abstract: A microcontroller and system allowing for more than one trial time in a furnace system, while using only one pin of the microcontroller. An alternating current signal at an input port of the microcontroller causes the microcontroller to allow a first long trial time period. Any direct current signal at the input port causes the microcontroller to allow only a second shorter trial time period. The trial time input port of the microcontroller is placed between two ports which either receive or send direct current signals. Due to this arrangement of the parts and construction of the microcontroller, the microcontroller will fail to the shorter and safer trial time if a fault causes an erroneous signal to appear at the input port.

Abstract: Time-delay circuit for automatic shutdown of furnace systems has an induced draft blower motor and a first circuit for providing energy to the blower motor from an energy source. A second circuit for energizing the primary control system of the furnace, includes a thermostat and an electronic switching means. When the thermostat is "closed", the second circuit is completed to energize the electronic switching element which starts the blower. An airflow switch is provided to sense the start of the blower and to thereby energize a primary control which provides gas to a burner of the furnace. A timer set to a predetermined time interval has an output and two input terminal connections, one connected to the output of the thermostat and another to the output of the primary control system. When the thermostat is "closed" and the burner is operating, the timer is disabled.

Abstract: A low cost hot surface ignition system particularly adapted for use in gas furnaces and the like, the system including low voltage control and timing circuitry effective to control a gas valve and high voltage ignition circuitry incorporating a hot surface silicon carbide igniter disposed in the path of incoming gas and in the heat of the flame when ignition is achieved to effect flame rectification resulting in flame sensing. The system also provides fail-safe operation or safety shutdown of the associated furnace if ignition is not achieved or in the event of a failure of a component of the system.

Abstract: A hot surface ignition system for a gas furnace or the like, control device therefor and methods of making the same are provided, the system comprising a burner, a settable thermostat, an electrically operable gas valve, a control unit, and an electrically operable hot surface igniter disposed so as to be in the path of gas issuing from the burner that is adapted to be fed the gas from a source thereof through the gas valve when the control unit has been activated by the thermostat to operate the igniter and the gas valve in a certain sequence, the control unit having a lockout unit for deactivating the system should ignition of the gas issuing from the burner not take place by the end of the certain sequence, the control unit having a resetting unit for causing the control unit to be reactivated to be adapted to repeat the certain sequence of the system when the resetting unit is activated, the control unit being adapted to select the certain sequence to have one or more attempts of the control unit to ignit

Abstract: An integrated electronic control arrangement is disclosed in the illustrative environment of burner such as in a gas-fired furnace. The control incorporates a self-test feature which shuts down the furnace in the event of any one of a number of possible sensed faults. Self-testing occurs automatically before an attempt at ignition and during furnace operation. Proper functioning of the sensor which senses for induced air flow through the burner combustion chamber is tested prior to enabling a fan which causes that induced air flow. Air flow is confirmed by sending to and receiving back from the sensor a sequence of pulses. Should air flow not be sensed during a combustion period, combustion is terminated. A flame sensor is provided for determining the presence of a flame in the combustion chamber. During times when a flame should be present, pulse sequences are sent to and received back from the flame sensor to confirm that a flame is present.

Abstract: A gas valve for controlling the flow of a combustible, gaseous fuel to a burner employs a modular construction and is configurable to be fast or slow opening, to be step opening or to provide two firing rates in accordance with external signals applied thereto.

Abstract: An automatic controller for a master gas switch includes a timer for keeping the switch opened for a selectable time. The controller includes an electrical motor for rapidly closing the switch. The motor is responsive to two conditions: When the timer reaches the end of a selectable time, it energizes the motor to cause the gas switch to close. Secondly, a flame induction rod monitors a gas burner flame, and when the flame stops, such rod causes a relay to close and energize the motor for gas switch closure.

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: An ignition control system for a direct ignition gas appliance, such as a furnace. A main gas valve, spark generator, flame sensor, and purge blower are all interconnected to a single controller. The controller issues a purge signal to the blower for a first predetermined period. Thereafter, for a second predetermined period, the controller issues an interconnect signal to allow the main gas valve to open and an ignition signal to cause the ignition source to ignite the gas flowing into the appliance from the valve. If the controller thereafter fails to receive a signal from the flame sensor, the attempt at ignition was unsuccessful. After a predetermined number of unsuccessful attempts at ignition, the controller issues a lockout signal to the valve. Moreover, the controller includes redundant circuits for detecting malfunctions within itself and responsively closing the main gas valve.

Abstract: A control system including a valve for controlling the flow of fuel to a burner, a resistive heater element connected between first and second terminals and disposed for igniting fuel emanating from the burner, an isolation transformer comprising a heater secondary winding connected to the first and second terminals so as to provide heating current to the heater element, and an electrode spaced from the heater element in a zone occupied by flame emanating from the burner. Also included is a start-up circuit for opening the valve to provide fuel to the burner for ignition by the heater element and a flame sensing circuit comprising an ac source, coupling means connecting the ac source means between the electrode and one of the first and second terminals with the secondary winding connected to the first and second terminals, and a detector circuit for detecting the flow between the electrode and the heater element of current conducted by flame in the zone.