Abstract: A heating or cooling system, such as an HVAC system, of variable output has a number of control elements and may include a variable speed compressor, a variable speed combustion (induced or forced draft) blower motor; a variable speed circulator blower motor; a variable output gas valve or gas/air premix unit; and a controller specifically developed for variable output applications. The system may utilize a pressure sensor to determine the actual flow of combustion airflow in response to actual space conditions, vary the speed of the inducer blower, and subsequently vary the gas valve output to supply the correct amount of gas to the burner system. A temperature sensor may be located in the discharge air stream of the conditioned air to provide an input signal for the circulator blower.

Abstract: A heating or cooling system, such as an HVAC system, of variable output has a number of control elements and may include a variable speed compressor, a variable speed combustion (induced or forced draft) blower motor; a variable speed circulator blower motor; a variable output gas valve or gas/air premix unit; and a controller specifically developed for variable output applications. The system may utilize a pressure sensor to determine the actual flow of combustion airflow in response to actual space conditions, vary the speed of the inducer blower, and subsequently vary the gas valve output to supply the correct amount of gas to the burner system. A temperature sensor may be located in the discharge air stream of the conditioned air to provide an input signal for the circulator blower.

Abstract: An HVAC system has at least one variable speed controller for an AC induction motor, especially of the Permanent Split Capacitor (PSC) type. The variable speed controller provides switched power via a modulating triac to the main coils of the motor and constant power via an on/off triac to the auxiliary coils during operation. A large value capacitor is placed in line with the auxiliary coils to reduce power consumption and current draw over that of known systems. Power to the motor can be turned off to provide for motor speed sensing through monitoring the frequency of a generated voltage when the power is turned off. Frequency-based motor speed sensing is accomplished by shutting off all current to the motor and measuring zero crossings on the generated voltage of the decaying magnetic field. The controller can be easily retrofitted onto existing motors. An optional controller bypass is provided to run the motor at rated speed in case of controller failure.

Abstract: A heating or cooling system, such as an HVAC system, of variable output has a number of control elements and may include a variable speed compressor, a variable speed combustion (induced or forced draft) blower motor; a variable speed circulator blower motor; a variable output gas valve or gas/air premix unit; and a controller specifically developed for variable output applications. The system may utilize a pressure sensor to determine the actual flow of combustion airflow in response to actual space conditions, vary the speed of the inducer blower, and subsequently vary the gas valve output to supply the correct amount of gas to the burner system. A temperature sensor may be located in the discharge air stream of the conditioned air to provide an input signal for the circulator blower.

Abstract: An HVAC system has at least one variable speed controller for an AC induction motor, especially of the Permanent Split Capacitor (PSC) type. The variable speed controller provides switched power via a modulating triac to the main coils of the motor and constant power via an on/off triac to the auxiliary coils during operation. A large value capacitor is placed in line with the auxiliary coils to reduce power consumption and current draw over that of known systems. Power to the motor can be turned off to provide for motor speed sensing through monitoring the frequency of a generated voltage when the power is turned off. Frequency-based motor speed sensing is accomplished by shutting off all current to the motor and measuring zero crossings on the generated voltage of the decaying magnetic field. The controller can be easily retrofitted onto existing motors. An optional controller bypass is provided to run the motor at rated speed in case of controller failure.

Abstract: A flame detector for a burner system having a flame during combustion that emits UV radiation, has a low gain UV sensor, a capacitor, a band pass filter receiving the capacitor's signal, and a rectifier receiving the band pass filter signal and providing a rectifier signal. A low pass filter receives the rectifier signal and provides a flame signal as an output whose magnitude is indicative of presence or absence of flame. An optical filter interposed between the UV sensor and the flame and having optical bandpass characteristics attenuating UV radiation outside the wavelength associated with the flame, improves operation.

Abstract: A circuit for detecting whether the level of an electrical signal having a preselected polarity is above a preselected value, is powered by DC of the opposite polarity. This prevents current leakage within the detector circuit from simulating the level of the electrical signal. Such a circuit is particularly suited for detecting the current level provided by a flame sensor in a combustion control system. The preferred embodiment has a capacitor which is charged by the circuit and then discharged by the electrical signal. The time required to discharge the capacitor to a preselected level indicates the level of the electrical signal. A second embodiment uses a comparator in a feedback loop which allows sensing the level of a voltage outside of the voltage range defined by the comparator's power supply.

Abstract: A burner control system periodically tests for and detects an out of range signal level from a flame sensor in the burner. When the system is in standby operation where no flame is present, the control system checks whether the flame signal level is within an abnormal range defined by a low margin level and a threshold level. When the system is in an operational phase where flame is expected, the system checks whether the flame signal level is within an abnormal range defined by a high margin level and the threshold level. Should either check detect the flame signal within an abnormal range, a signal is provided indicating this abnormal condition. Preferably, the abnormal condition is used to control the flashing of an indicator light, fast during standby phase if the flame signal level is too close to the threshold level and more slowly if the flame signal level is too close to the threshold level while flame is present. It is also possible to use two different lights for the indicators.

Abstract: A converter circuit provides an output signal of polarity opposite that of an input signal having a DC component and a low frequency periodic component in response to presence of that input signal. Current is transferred from a first capacitor to a second to accomplish this conversion. The circuit has particular application in a flame sensing interface circuit using a sensor of the infrared radiation generated by the flame to change the impedance of the sensor. By use of the circuit, the output of an infrared sensing amplifier imitates the output of a conventional flame rod sensor, and provides an output signal compatible with the output of a flame rod to the input to a flame signal processor.