Abstract: A device for protecting a cooking appliance, in particular a gas cooking plate or a gas cooker, with at least one gas burner which is connected to a gas main via a branch pipe and which is provided with a manually operated gas tap for opening and closing the branch pipe and an ignition mechanism, wherein the or each burner is provided with a sensor for detecting a gas flame, wherein a central processor is arranged which is connected to this sensor and which actuates a gas valve accommodated in the gas main, this such that the gas valve closes in the absence of a flame at the burner, whereby unsafe situations are prevented.

Abstract: Arrangement for interrogating multiple switch conditions employs a single input microprocessor for a plurality of switch elements that are coupled in series with an operating element and a power source. A variable oscillator has a control input and an output coupled to the microprocessor input, providing a periodic signal to the same. A plurality of impedance elements, e.g., resistors, each with a respective value, are coupled between a respective junction between two successive switch elements and the control input of said variable oscillator, such that the rate of said periodic signal varies as a function of the open or closed condition of the respective switch elements. For each switch being tested, the microprocessor looks for one predetermined frequency or pulse rate corresponding to an open condition and another corresponding to a closed condition.

Abstract: The present invention provides improved acoustic flame detection apparatus and methods for detecting the presence or non-presence of a flame from a location remote from the flame. The flame detection apparatus is comprised of a conduit extending between the location of the flame to be detected and the remote location, a sound detector connected to the conduit for detecting sound conducted to it by the conduit and generating a signal representative thereof and means for receiving the signal and indicating the presence or non-presence of the flame in response thereto.

Abstract: A radiation modulator system and related method for actively controlling a flame in a combustion system are provided. The system includes a plurality of radiation modulators positioned adjacent the flame. A sensor arrangement is provided for sensing combustion characteristics of the flame and generating a sensor signal representative of the combustion characteristics. The sensor signal is received in a computer which then generates a control signal for transmission to a linkage arrangement which provides for the repositioning of the radiation modulators. Thus, the flame is actively controlled by continually repositioning the modulators in response to the sensor signal and the control signal. The related method broadly includes the steps of: (1) positioning the radiation modulators adjacent the flame; (2) sensing combustion characteristics of the flame; and (3) repositioning the radiation modulators responsive to the combustion characteristics.

Abstract: A gas oven having an electronic controller for directly controlling the gas valve and burner ignition. The controller opens the gas valve and activates the ignitor whenever oven heating is required and then determines whether ignition has occurred, detected by an indicator of ignition, often a conventional oven thermostat, a thermocouple, a resistance temperature device (RTD), or other type of temperature sensor. Positive proof of ignition is given by determining whether the detected temperature is increasing at a particular rate. The gas valve is closed if ignition does not occur within a predetermined time, preferably about 10-15 seconds. Re-ignition may be attempted after a sufficient delay. The controller also closes the gas valve whenever the oven temperature is decreasing at a predetermined rate or is increasing at less than a predetermined rate.

Abstract: A gas burner operation monitoring apparatus for enabling convenient diagnosis of gas burner and control problems. The invention is a temporarily attached device that collects and stores information concerning the key functions indicative of an gas burner's operation. If a fault occurs, the apparatus generates a signal to indicate to a downstream microprocessor, if such is connected, that a problem has occurred. This eliminates the need for the technician to randomly replace parts until the problem is located. The system monitors the status of the thermostat or aquastat; the presence and the level of voltage being sent to the main gas valve; the pressure of gas at the inlet and outlet of the main gas valve and either the temperature on the outside of the vent stack pipe or the presence and quality of flame at the main gas burner. The device also provides a signal in the event of a fault that can be connected to a downstream microprocessor that, in turn, can activate various warning devices.

Abstract: A detection system includes flame sources at least two of which are independently controllable; photodetectors each having an independent view of the flame sources and being capable of producing a respective current signal in response to flames produced by the flame sources; and a device for analyzing the current signals to determine state values of a plurality of state variables and transform the state values into at least one parameter value. A number of the flame sources is at least as high as a number of the state variables, and a number of the photodetectors is at least as high as the number of the state variables. In one embodiment, the flame sources include gas burners in a gas combustion chamber, the photodetectors include silicon carbide photodiodes, and the parameter value is representative of fuel rate, temperature, acoustic dynamics, nitrogen oxide concentration, or carbon monoxide concentration.

Abstract: The invention relates to motor vehicle heating device with a burner, to which combustion air is supplied via combustion air inlet openings by means of a fan and to which furthermore fuel gas is supplied via a fuel gas supply line, combustion air and fuel gas entering on the intake side of the fan. It is provided according to the invention for a simpler structure and good mixing of the fuel gas/combustion air mixture that entry of fuel gas is controlled by means of a valve or switch controlled by the negative pressure of the fan. Fuel gas is supplied in doing so, preferably, with a negative pressure which is less than atmospheric pressure. For especially simple control of gas supply, there is a membrane which causes the fuel gas supply line to close when the fan stops.

Abstract: An ignitor includes a first transistor, a transformer, an ignition member, and a switching control member. The first transistor is activated in accordance with supply from a DC power supply to perform switching. The transformer has a primary winding through which a switching current flows via the first transistor, a secondary winding for generating high voltage when the switching current flows through the first winding, and a tertiary winding for generating a control output for controlling the switching of the first transistor in accordance with the high voltage generated in the secondary winding. The ignition member ignites a target object using the high voltage generated in the secondary winding of the transformer. The switching control member prolongs the ON time for the switching of the first transistor in accordance with a decrease in at least one of the ambient temperature and the power supply voltage.

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: The invention relates to a gas/air ratio control apparatus for a temperature control loop for household gas appliances, in particular for domestic/direct hot water units and combined direct hot water/central heating units, for temperature control of domestic and/or heating water. The invention is particularly suitable for household appliances up to 120 KW. The gas/air ratio control apparatus comprises a controllable fan (3) for supplying a predetermined air stream (2-2) to a burner (4) in dependence on the detected actual temperature (T.sub.Actual) and the desired target temperature (T.sub.Target) of the heating and/or domestic hot water; and a pressure-controllable valve (8) for controlling the supply of a specified fuel quantity (1) to the burner (4) in dependency exclusively on the absolute pressure of the air stream (2-2) produced by the controllable fan (3).

Abstract: An oil burner operation monitoring apparatus for enabling convenient diagnosis of burner problems. The invention has two major components: a permanently mounted or integral data collection unit that is connected to key points in the oil burner and a portable data reading unit. The data collection unit records and stores information concerning the key functions indicative of an oil burner's operation. If a fault occurs, the apparatus generates a signal to indicate to a downstream microprocessor, if such is connected, that a problem has occurred. The oil burner technician, using the portable data reading unit, connects to the data collection unit accessing the stored information in the data collection unit concerning the reason for the problem. This eliminates the need for the technician to randomly replace parts until the problem is located.

Abstract: The present invention provides a novel system for monitoring a predetermined operating condition of a heating apparatus, such as a cumulative total time period of combustion and a combustion frequency, and informing a user of a timing of maintenance. In a hot water heater (1) according to the invention, a controller (208) outputs a maintenance requirement signal to a display (210) and a maintenance alarm to inform the user of a timing of maintenance when a combustion frequency nx becomes equal to or greater than a first reference value nr1 or when a cumulative total time period of combustion tx becomes equal to or greater than a second reference value tr1. This allows the user to perform maintenance without delay and prevents troubles or abnormalities from being developed in the hot water heater (1).

Abstract: A burner system for a radio-controlled hot air balloon. The frame that is connected to an envelope contains two fuel tanks. One fuel tank is disposed right side up and delivers fuel in vapor form to a pilot burner mechanism. The other fuel tank is inverted and delivers in liquid form to a burner coil means. The flame of the pilot burner mechanism partially heats the liquid fuel in the burner coil means so that when a valve member is opened, fuel in a vaporous mist form is discharged from an outlet orifice of the burner coil means for ignition by the flame of the pilot burner mechanism. A radio-controlled servo is connected to the valve member and operates the same.

Abstract: A camera includes a plurality of photosensors disposed on an imaging surface. The photosensors separately output respective photodetection signals, and are grouped into a plurality of photosensitive units each including at least two of the photosensors. The photosensors of each of the photosensitive units have respective detection wavelength ranges which do not overlap one another. The photodetection signals outputted from selected ones of the photosensors of each of the photosensitive units are used in performing spectrum analysis. R (red), G (green), and B (blue) signals are synthesized from the photodetection signals outputted from the photosensors of each of the photosensitive units and are used in displaying an ordinary color image.

Abstract: A fuel control system, a control device therefor and methods of making and operating the same are provided, the fuel control system comprising a source of fuel a burner unit, an electrically operated valve unit adapted to be opened to interconnect the source of fuel to the burner unit when the valve unit is energized, the valve unit having a coil, an electrical power source having a value sufficient for opening the valve unit when operatively interconnected to the coil to energize the coil, a control device for operatively interconnecting the power source to the coil when the control device determines that fuel should be directed to the burner unit, the control device being so constructed and arranged that the control device is adapted to operatively interconnect the power source to the coil without the use of relay contacts between the power source and the coil.

Abstract: A control or regulating system for an automatic heat furnace is disclosed. This control system simplifies the construction of automatic gas furnaces for heating plants. The control system operates the furnaces with a high degree of efficiency and low pollutant emission, even at partial capacity. The adjusting element or mechanism for air is a blower with adjustable rotational speed which is driven by a motor. The motor is controllable by, preferably, digital pulse-width modulated control signals of a control aggregate acted upon by a regulator. A gas valve regulates the pressure of the gas supplied to the burner as a function of the air pressure in the line leading from the blower to the burner.

Abstract: An oil burner operation monitoring apparatus for enabling convenient diagnosis of burner problems. The device is connected to key points in the oil burner. The device records and stores information concerning the key functions indicative of an oil burner's operation. If a fault occurs, the apparatus generates a signal to indicate to a downstream microprocessor, if such is connected, that a problem has occurred. The oil burner technician can access the invention for the information concerning the reason for the problem. This eliminates the need for the technician to randomly replace parts until the problem is located. The system monitors the status of the thermostat; the presence and the level of voltage powering the ignition transformer and temperature on the outside of the vent stack pipe. The device also provides a signal in the event of a fault that can be connected to a downstream microprocessor that, in turn, can activate various warning devices.

Abstract: A turn down device for regulating gas flow within a gas lamp that is of the general type having a lamp post and a mantel. The device has a conduit configured to allow gas to flow therethrough and a gas supply line connected to the conduit for supplying gas under pressure. A poppet valve having a valve seat and a magnetic poppet is provided along the conduit downstream of where the supply line connects to the conduit. A solar cell is connected to the electromagnet that generates and provides to the electromagnet a voltage which varies depending upon sunlight at the solar cell. The popper is fabricated so as to have a selected size, shape and mass such that the gas flow from the supply line lifts the poppet away from the valve seat absent attractive forces induced at an electromagnet provided proximate the valve. As varying amounts of sunlight are directed upon the solar cell, electricity travels to the windings of the electromagnet that induces an attractive electromagnetic force upon the valve.

Abstract: An outdoor lamp has a solenoid valve which controls the feed of gas and mixed with air to an electrically conducting venturi table and thence to burner tips which are surrounded by mantles. An electrode disposed adjacent to a slit in the venturi tube creates a spark adjacent to the slit when the valve is electrically opened to light the gas mixture which subsequently lights the gas mixture at the tips. An electrical circuit has a photocell array which causes the electrical circuit to open the valve at dawn with a shot of electricity and closes the valve at night with another shot of electricity. A sensor in the circuit detects when the lamp is lighted and discontinues the spark.

Abstract: A dimmer device for a gas light which is solar activated and is composed of a minimum number of parts. A magnetically operated valve with a magnetically attractable ball is energized during daylight hours to close off one passageway yet allows gas to flow through a second passageway at a lower flow rate to provide a dimmer condition for the lamp. At night time, the magnetic valve is deactivated causing the magnetically attractable ball to open the otherwise closed passageway and thereby allow full gas flow to the lamp. The dimmer device is easily installed into the lamp housing rather than the post.

Abstract: Pressure variation of combustion noise is detected by a microphone set in a combustion chamber, and the pressure propagation characteristic for the path from the gas flow control valve to the microphone is identified while the combustion apparatus is operating, and then an adaptive control is made using one signal detected by an microphone and the other signal produced by passing the signal of the microphone through a filter, and then a corrected anti-phase signal of a combustion noise is computed by the coefficient updating circuit, and the computed result is inputted to a gas flow control valve.

Abstract: A circuit for producing signals representative of at least two flame current levels is disclosed herein. The circuit includes two electrodes locatable in a flame, where a voltage potential is set up between the electrodes, and the current flow is measured therebetween (flame current). The circuit includes an amplifying portion for amplifying the flame current and applying a signal to a microprocessor. The microprocessor samples the signal and outputs a signal representative of the flame current level.

Abstract: An apparatus for detecting the presence of polycyclic aromatic hydrocarbons in the effluent of a turbulent commercial combustion system for monitoring or controlling the composition of the effluent. The apparatus is a system for directyl selectively detecting the presence in the effluent high molecular weight polycyclic aromatic compounds having five or more rings by laser induced fluorescence. The system includes an illuminating source of select fluorescence excitation of wavelengths that induces substantial fluorescence by high molecular weight polycyclic aromatic hydrocarbons in the gas phase.

Abstract: A method and apparatus for the early detection and relief of a closed, pressurized gas charged system, such as an ammonia refrigeration system, wherein a central control system measures and assimilates system and ambient conditions, and responds to alleviate system pressures in excess of design parameters, and, further, combusts system gasses so relieved, breaking such gasses into nontoxic byproducts of combustion.

Abstract: A gas burner includes a single valve for adjusting the flame size. A plurality of push buttons is provided for adjusting that valve to respective positions of adjustment, so that the flame size depends upon which button is pushed.

Abstract: Gas fired donut cooking system for automatic cooking of donuts featuring a low voltage controlled gas fired tube for heating of the cooking oil. Operation is powered from ordinary household current or can be powered by a storage battery and a power inverter at a remote site where household current is unobtainable. Propane or butane gas is supplied from a bottle.

Abstract: A HVAC system (10) employs a gas valve (20) to supply gas for combustion within a heating portion (12) of the system. An exhaust (22) removes combustion products using a motor (28) driven exhaust fan (24). An apparatus (34) controls combustion and uses a sensor (36) for sensing the rotational speed of a motor shaft (26). A switch (T1) is responsive to sensed motor speed to open and close the valve, the valve being opened only if the motor is operating within a predetermined speed range. A first speed discriminator (48A) enables of the switch to open the valve when the motor speed exceeds a first predetermined value. A second speed discriminator (48B) disables the switch to close the valve when motor speed exceeds a second and higher predetermined speed which is indicative of a blocked exhaust, or a fan blade is loose. This latter action insures that a build-up of potentially dangerous exhaust gases cannot occur.

Abstract: A calculator apparatus 10 includes the standard calculator mode and several other modes functions namely; a pressure-temperature conversion, a temperature-to-pressure conversion based on refrigerant, a relative humidity reading based on input of the dry bulb and wet bulb temperature; and a flow-energy rate conversion mode based upon a selected fuel meter dial and Metric or English units. In addition, a Fahrenheit-to-centigrade conversion and a centigrade-to-Fahrenheit conversion functions are incorporated. The calculator includes a keyboard 18, a microprocessor 16, a timer 26, a power source 12, a switch 14 and a display screen 22.

Abstract: A control system for a burner is disclosed which detects oxygen concentration in a room using an oxygen sensor, to thereby supply an abnormality detecting signal to at least one of an alarm and a combustion reducing device to actuate it when oxygen concentration is lowered below a predetermined set value. A first comparing device and a reference value storing device are used to cause maximum oxygen concentration detected to be stored as an oxygen concentration reference value in the storing device. A second comparing device compares the deviation between the oxygen concentration reference value and a detected oxygen concentration value with an abnormality judging reference value, to thereby generate the abnormality detecting signal when the deviation is larger than the reference value. The control system is capable of effectively detecting a low oxygen concentration condition without being affected by an ambient temperature.

Abstract: The present invention is a furnace control system responsive to a circulator fan motor fault condition. Upon detection of the fault, the control determines a first time period which is required to activate the temperature limit switch of the furnace by continuous operation of the gas burner and a second time period which is required for the plenum to dissipate sufficient heat to deactivate the temperature limit switch. After determining the first and second time periods, the furnace control operates the burners for a fraction of the first time period and then allows the heat exchangers to cool for the second time period until the circulator fan motor fault is corrected or the demand for heat ceases.

Abstract: In this air-conditioner, combustion test of a refrigerant heater is conducted through a control valve on the basis of a minimum combustion command signal and a maximum combustion command signal set in advance at a plurality of stages to store values of the minimum combustion command signal and the maximum combustion command signal presenting an optimum combustion state from the above-mentioned command signals, whereby in an actual operation, control of the control valve is carried out by using stored values with respect to the minimum combustion command signal and the maximum combustion command signal.

Abstract: A fuel-fired, forced draft heating appliance includes a draft inducer fan having an inlet connected to a vent hood, an outlet connectable to a vent pipe, and an interior housing region in which a negative pressure is generated during normal appliance operation. The vent hood receives hot combustion gases generated by the appliance, and has an inlet for receiving ambient dilution air that mixes with and cools the combustion gases entering the hood and subsequently discharged into the vent pipe by the fan. A combination pressure and temperature limit control is used to sense the presence of an obstruction in either the vent pipe or the vent hood inlet and responsively shut down the appliance. The control includes a vacuum switch external to the fan, a bimetallic disc-type temperature sensor disposed within the negative pressure fan region, and a conduit interconnecting the switch and the temperature sensor.

Abstract: Apparatus for controlling a heat generating device having automatic adjustment of water temperature to heating requirements, and also for protecting such devices from being switched "on" and "off" too frequently, includes a control relay or a main relay having a "pause" imprint contact for switching "off" and an "on" contact, as well as a chronometric device for measuring how long the heat generating device is switched "on" and for setting an "off" pause imprint interval which is inversely variable according to the measured length of time the heat generating device is switched "on".

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 leak detector for a valve controlling flow of fuel to a combustion chamber employs a fuel concentration sensor in a sensing chamber placed downstream from the valve seat. The valve has a downstream chamber which is in communication by diffusion through an orifice, with a source of pressurized air. By injecting air into the downstream chamber through this orifice after the valve has closed and then measuring with the sensor the fuel concentration within the sensing chamber, excessive fuel leakage by the valve can be detected.

Abstract: A digital control system, for a gas-fired, forced combustion air heating appliance, controls operation of a combustion air blower and a gas valve as a function of essentially square wave input signals derived from a thermostat, a combustion air proving sensor switch, and a gas valve control relay. When a first input signal from the thermostat demands heat, the control system first checks for the presence of a second input signal (which indicates the status of the combustion air sensor switch) before starting the combustion air blower. If the second input signal indicates that combustion air is being delivered before the combustion air blower has started, the control system immediately halts the ignition sequence. If the combustion air sensor switch is functioning properly, the ignition sequence continues and the control system checks a third input signal to determine the status of the contacts of the gas valve relay.

Abstract: A control system, for a gas-fired, forced combustion air heating appliance, controls operation of a combustion air blower and a gas valve as a function of signals from a thermostat, a combustion air proving sensor switch, and a gas valve control relay. When the thermostat demands heat, the control system first checks the status of the combustion air sensor switch before starting the combustion air blower. If the combustion air sensor switch indicates that combustion air is being delivered before the combustion air blower has started, the control system immediately halts the ignition sequence. If the combustion air sensor switch is functioning properly, the ignition sequence continues and the control system checks the status of the contacts of the gas valve relay.

Abstract: A method and circuit for self-checking problems in a heating system for an automobile are disclosed. A self-checking and indicating process are disclosed which include a first preheating step; an ignition period; a second preheating step; a combustion period module; and an extinguishment step according to a program interrupt. Various checking steps are included, along with various subroutines for indicating errors. Errors are displayed and a stopping step is performed if the temperature checked and the various proceding checking steps indicate that error conditions exist. The present invention includes an indicating apparatus which includes an output part of a microprocessor which provides a fundamental memory, a data processor, an arithmetic and logic accumulation, and an interrupt. The microprocessor is connected to an output part of a driving apparatus, and a sensing part which senses the driving state of the output part, the ignition, the temperature, and a low voltage condition.

Abstract: Flame monitoring is normally performed in a space heater for a motor vehicle in order to stop the fuel supply within a certain period of time in the case of interruption of the flame. If interruption of the flame is detected by measuring the temperature on the heat exchanger or the combustion chamber of the heater in order to detect a possibly relatively rapid temperature drop, it must be ensured that the temperature at the test point can indeed decrease rapidly enough. It is therefore necessary constantly to monitor the electric motor of the blower for the combustion air or for the heating air flowing past the heat exchanger, so that the combustion chamber or the heat exchanger will indeed cool after interruption of the flame. The operation of the blower motor is monitored by briefly interrupting the power supply and measuring the generator voltage generated by the motor that continues to rotate. If there is no generator voltage or it is too low, a malfunction indication is generated.

Abstract: A burner control for a condensing furnace having a flame proving circuit that incorporates the flame at the burner to be closed and that opens upon absence of a flame to cause a gas valve to close and block the flow of gas to the burner. A short circuit shunting the flame proving circuit includes a probe that projects into the outlet manifold of the condensing furnace. If liquid level in the outlet manifold reaches the probe, a short circuit is closed between the probe and a ground on the manifold. The control to the valve is energized to close the valve in the same manner as if the flame had extinguished at the burner. Upon closing the gas valve, the burner is extinguished.

Abstract: The present invention is a method and apparatus for conditioning an AC input signal to a control system having a plurality of AC input signals. An AC system signal is substantially phase-synchronous with the AC input signal. The AC input signal is sampled a plurality of times to determine whether it is present or absent during a periodic half cycle of the AC system signal. A result value is determined which represents a state of the AC input signal determined a majority of the times that it was sampled. It is then determined whether the state of the result value has changed.

Abstract: An oil stove comprises a combustion wick for burning oil, a device for extinguishing the fire at the combustion wick, and a deodorizing device for absorbing or removing gases causing smells that are produced when the burning portion at the combustion wick is extinguished. The deodorizing device comprises gas sensing means for detecting the generation of the gas, and suction means responsive to the gas sensing means for absorbing or removing the gas.

Abstract: A flame powered logic supply circuit (60) responds to a pilot flame (39b) and supplies electrical energy to power electronic logic circuitry (62) for a heater, such as a hot water heater (1), a furnace, or the like. A thermoelectric element (64) responds to the flame and outputs electrical current which is stored in an inductor (70). A pair of parallel circuit branches (78 and 80) are connected to the thermoelectric element (64) and the inductor (70). The first branch (78) has a semiconductor switch (82) with an on state during which current flow supplies energy to the inductor (70) which is stored therein. The second circuit branch (80) has a second energy storage component provided by a battery (90) which receives the stored energy from the inductor (70) during an off state of the semiconductor switch (82) to charge the battery (90) and maintain a given power rating thereof for powering electronic logic circuitry (62) of the heater.

Abstract: A method and apparatus determine signal quality of AC input signals to a control system where the AC input signals and an AC system signal are phase-synchronous. A read cycle, for reading the AC input signals, is scheduled to be performed during periodic cycles of the AC system signal. The presence or absence of the AC system signal is determined. A number of good read cycles are counted where the good read cycles represent the read cycles performed when the AC system signal is present. A ratio is determined between the number of good read cycles counted during a predetermined time and a total number of read cycles scheduled to be performed during the predetermined time.

Abstract: The present invention is a method and apparatus for preventing a decision made by a controller from being made based on incomplete information where the controller periodically runs a decision making routine. The controller makes decisions based on a plurality of AC input signals being present or absent. The presence or absence of the AC input signals is read by the controller during a read cycle performed during periodic half cycles of the AC system signal. The AC system signal and the AC input signals are substantially phase-synchronizes. Before the controller runs the decision making routine, the controller determines whether the presence or absence of the AC input signals has changed since the previous decision making routine. Where the presence or absence of the AC input signals has changed since the previous decision making routine, the decision making routine is delayed for a predetermined number of half cycles of the AC system signal.

Abstract: A control unit for a gas furnace that has an electrically operable pilot gas valve and an electrically operable main gas valve and a method of making the control unit are provided, the control unit comprising an electrical circuit having a gas valve section that comprises a silicon controlled rectifier and a first capacitor and a second capacitor so electrically interconnected together that the capacitors are adapted to be charged on each half wave cycle of a certain polarity of an alternative current source that is imposed on the circuit and that second capacitor is adapted to discharge through a relay coil that controls the gas valve to energize that relay coil only when the silicon controlled rectifier conducts, the silicon controlled rectifier being adapted to conduct only when the first capacitor is discharged, another section of the electrical circuit being adapted to discharge the first capacitor only on each half wave cycle of the other polarity of the alternative current source.

Abstract: A control circuit for controlling the ignition time of a control system for a gas-fired combustion air heating appliance comprising a set of potentiometers and a controller for detecting failures in the control circuit. The set of potentiometers are used together to select the ignition time of the control system. The potentiometers are set to produce analog input signals which, when converted to digital signals, have a predetermined complementary relationship (such as one's or two's complement). The controller is connected to the set of potentiometers and includes an analog-to-digital converter which receives the analog input signals from the set of potentiometers and converts them into digital signals. The controller compares or analyzes the digital signals derived from the first and second potentiometers to detect failures in the control circuit and halts operation of the control system if the digital signals do not have the predetermined complementary relationship.

Abstract: In an inducted draft, fuel-fired furnace a flow restriction in the external exhaust flue is detected, and the furnace burners responsively deactivated, by a thermal sensing switch mounted in a spaced relationship with a small flow opening formed in a sensor housing externally secured to the inducer fan outlet section over a wall opening therein. During normal burner combustion product discharge flow through the exhaust flue, a small vane within the inducer fan outlet section creates a venturi therein which draws ambient air within the furnace housing across the temperature sensing switch and into the fan outlet section through the sensor housing opening. The temperature of this ambient air is below the switch set point so that continued burner operation is permitted.

Abstract: A heater device for a motor vehicle detects the temperatures of a burner and a heat exchanger when the heater device is shut off. When the detected temperatures reach respective preset values, a combusting blower for supplying combusting air to the burner and a heating blower for supplying heating air to the heat exchanger are actuated to introduce cooling air to the burner and the heat exchanger for thereby preventing the burner and the heat exchanger from being overheated.