A method for controlling operation of a fuel-fired heating appliance having a burner, a fuel flow control for controlling a fuel flow to the burner, and a combustion air blower for supplying combustion air to the burner, includes iteratively (1) determining the quality of combustion by sensing a flame at the burner and outputting a time-varying flame current signal that includes an ionization signal from the flame; sampling the flame current signal to obtain a time record of the flame current signal; using a Fourier transformation, transforming the time record into a frequency spectrum of frequency components that include frequency components of the ionization signal, the frequency spectrum having a spectrum shaped defined by various frequency components of the flame current signal; and determining whether the frequency spectrum indicates flame stability or instability. Upon determination of flame instability, adjusting at least one of the fuel flow control to decrease the fuel flow to the burner and the combustion air blower to increase the flow of combustion air to the burner, and shutting down the burner if flame stability is not determined within a predetermined interval.

A system for changing a bias level of a flame sensing circuit to identify leakage in the flame sensing circuit. The bias level may be varied in the positive or negative axis and the flame current may be noted to identify leakage. The bias level may be changed by a microcontroller. The bias level may be changed using an operational amplifier configuration which is used as a signal conditioner for interfacing the flame signal to the microcontroller.

The present invention is a burner flame detector to detect a flame at a farthest end of a burner using a flame rectification rod. It comprises of a rod-element comprising of an inner electric-wire, an electrically insulating material surrounding the inner electric-wire, a metallic tubular outer rod protecting the insulating material and the inner electric-wire. The metallic tubular outer rod is electrically insulated from the inner electric-wire, and a flame rectification sensor is attached to the rod-element at the farthest end of the burner, which goes through the flame. The flame rectification sensor becomes exposed to a flame and sends a flame rectified signal to a controller, through the inner electric-wire.

A flame scanner (10) includes terminals (32) for connection to a controller (50) The flame scanner includes a photodiode (14) to generate a detection signal; and a signal conditioner (20) coupled to the photodiode, the signal conditioner to generate an output signal across the terminals, the output signal emulating an output of an ultraviolet tube flame scanner.

A burner system and a retrofit flame control system for an existing burner system are disclosed. The burner system may include burner components, electrodynamic components, and a data interface. The data interface may receive a command for controlling the burner components and prepare a command for controlling the electrodynamic components at least partially based on the command for controlling the burner components.

A system for changing a bias level of a flame sensing circuit to identify leakage in the flame sensing circuit. The bias level may be varied in the positive or negative axis and the flame current may be noted to identify leakage. The bias level may be changed by a microcontroller. The bias level may be changed using an operational amplifier configuration which is used as a signal conditioner for interfacing the flame signal to the microcontroller.

A gas burner system has a gas burner with a conduit through which an air-gas mixture is conducted; a variable-speed forced-air device that forces air through the conduit; a control valve that controls a supply of gas for mixture with the air to thereby form the air-gas mixture; and an electrode configured to ignite the air-gas mixture so as to produce a flame. The electrode is further configured to measure a flame ionization current associated with the flame. A controller is configured to actively control the variable-speed forced-air device based on the flame ionization current measured by the electrode so as to automatically avoid a flame harmonic mode of the gas burner. Corresponding methods are provided.

A gas cooktop appliance includes a burner, a gas supply circuit in fluid communication with the burner, and a valve for controlling an amount of gas supplied to the burner from the gas supply circuit. An electrode is configured to provide an ignition spark and to obtain an ionization current. A control system is operably coupled with the valve and is configured to compare the ionization current to a setting of the valve and modify the amount of gas supplied to the burner when the difference between the ionization current and the setting of the valve is outside a predetermined threshold.

Disclosed are a flameout protection system and a heater. The flameout protection system includes a stove head, a double-needle electrode rod, an electromagnetic valve and a plasma controller. The stove head is provided with an ejection tube and a flame hole. The double-needle electrode rod is connected to the ejection tube, and one end of the double-needle electrode rod is close to the flame hole. The electromagnetic valve is connected to the ejection tube, and the electromagnetic valve is communicated with the flame hole. The plasma controller is electrically connected to the double-needle electrode rod, and the plasma controller is electrically connected to the electromagnetic valve.

A modular flame amplifier system having a base module, a burner control and one or more flame amplifier modules connected to the burner control. One or more sensors may be connected to the one or more flame amplifier modules. Some of the flame amplifiers may be a long distance from the burner control module. Some of the flame amplifiers may be connected to the burner control via a cable. The connection between some of the flame amplifiers and the respective sensors may be less noise tolerant than the long cable connection between the one or more flame amplifiers and the burner control. One or more flame amplifiers may be mounted on the same rail as the burner control or another rail remote from the burner control. Two or more sensors may be connected in one or more of several configurations along with delay in some configurations.