Methods and apparatus to indicate presence of a flame are disclosed. An example gas grill includes a burner tube having apertures to emit a fuel for combustion, an ignition element to cause ignition of the fuel emitted from the apertures of the burner tube, a flame sensor to detect the presence of a flame associated with the combustion of the fuel emitted from the apertures of the burner tube, and flame sense circuitry including a flame signal accessor to access a flame sense signal from the flame sensor, and a terminal to output an indication of the presence of the flame, the indication of the presence of the flame output without respect to an open or closed state of a lid of the grill.

A method and an apparatus for protection of a combustion unit of a chemical process against over firing, the burner(s) of the combustion unit are limited by a fuel and duty limiter which limits the duty based on process feeds, combustion gas and fuel flows.

A flow control apparatus includes a flow control signal generation device for generating a DC control signal based on an audio signal and at least one proportional valve. The flow control signal generation device includes an audio receiving module, a filter rectifier module, a microprocessor and a proportional valve control signal generation module. The filter rectifier module generates at least one DC audio signal by filtering the audio signal provided by the audio receiving module. The microprocessor generates a plurality of period attenuated values based on the DC audio signal. The proportional valve control signal generation module filters the audio signal, attenuates the signal based on the period attenuated values, and then performs filtering and rectification processing to generate the DC control signal, such that the proportional valve may control the opening ratio of the proportional valve based on the DC control signal.

Gas cooktops disclosed herein may include a proportional solenoid valve controlling gas flow to a gas burner, where the proportional solenoid valve has a continuously variable range of positions. A user interface (UI) element associated with the proportional solenoid valve may be utilized to control a linear voltage regulator having a continuously variable output voltage. The output voltage of the linear voltage regulator is coupled to a solenoid of the proportional solenoid valve, such that the gas flow to the gas burner has a linear relationship with the output voltage of the linear voltage regulator.

A dual-gas source gas control system with anti-gas source misconnection and a control circuit thereof belonging to the gas combustion technical field are provided. The disclosure solves unreasonable design and other problems in the related art. The dual-gas source gas control system with anti-gas source misconnection and the control circuit thereof includes a power-on circuit, connected in series with an external power supply and an igniter switch to form a loop, including a self-locking switch triode connected in series with the external power supply and a self-locking amplifying triode connected to a base electrode of the self-locking switch triode; an MCU control circuit, including an MCU control chip, wherein the power-on circuit is connected to a power input pin of the MCU control chip, one pin on the MCU control chip is configured to detect whether the power-on circuit is connected.

A system for controlling digital gas valves of an appliance utilizing a configurable duty cycle responsive to time, temperature and burner power level variables.

A heating control system that includes a heating unit with a constant burner and a pulsed burner. The constant burner is configured to remain active during operation. The pulsed burner is configured to toggle between an active mode and an inactive mode. The heating control system further includes a memory operable to store a temperature map that maps temperatures to percentages of a period that the pulsed burner is active and a microprocessor operably coupled to the heating unit and the memory. The microprocessor is configured to transmit a first electrical signal to activate the constant burner, obtain a temperature set point, determine the percentage of the period that the pulsed burner is active using the temperature set point and the temperature map, and transmit a second electrical signal to toggle the pulsed burner based on the determination of the percentage of the period that the pulsed burner is active.

In an aspect, an HVAC system includes an inducer motor to provide combustion airflow, and a pressure sensor to measure an output airflow pressure of the inducer motor. The HVAC system may initiate the inducer motor, and receive a pulse width modulation (PWM) signal from the inducer motor, wherein the PWM signal indicates a PWM signal of the inducer motor corresponding to a predetermined airflow pressure of the inducer motor and measured by the pressure sensor. The HVAC system may compare the PWM signal to a baseline value, and control the inducer motor based on the comparing of the PWM signal to the baseline value. The HVAC system may also generate a status notification of the combustion airflow of the HVAC system in response to the comparing the PWM signal to the baseline value.

A gas burner assembly and a method of operating the same are provided. The gas burner assembly includes fuel regulating device for providing a flow of fuel and an air pump for providing a flow of air to a boost burner for combustion. The method includes stopping the flow of fuel using the fuel regulating device and ramping down the operation of the air pump to slowly stop the flow of air. For example, the flow rate of the flow of air may decrease linearly over a predetermined time period to ensure a lean fuel/air mixture is not provided to the boost burner which may result in undesirable flame characteristics.

A flame detection system is designed to detect leakage in flame sense circuits. The flame detection system includes a flame sensor, an amplifier, a detection circuit, and a microcontroller. Flame sense circuitry use operational amplifiers that needs negative voltage supply for its operation. Negative supply voltage properly measures negative input signals. Once a leakage current in the flame detection system is determined a shutdown signal is provided to shut down a flame sensor when the leakage current condition is determined.