In a gas hot water heater, changes of the signal output of an A/F sensor are calibrated in the atmosphere, in which the A/F sensor detects an oxygen concentration in a combustion tube. The gas supplied via a gas supply pipe is injected, together with in-taken air, into a combustion tube, which is incorporated in a hot water supply tank, via an injection unit. A proportional valve controls a combustion state in the combustion tube based on the detected oxygen concentration to thereby heat water supplied in the hot water supply tank. A purging process is performed to supply air into the combustion tube, at a timing between an extinguishment operation first performed after the ignition the gas mixture in the combustion tube and a re-ignition operation. Changes of signal output characteristics of the A/F sensor are subject to the calibration after the purging process.

A flame sensing system, a flame sensing unit, and a method for sensing a flame are described. The flame sensing system includes a flame sense probe and a power regulating device. The power regulating device is configured to generate a regulated voltage from an input voltage received from a power source and to output the regulated voltage to the flame sense probe such that a flame current along a flame can be measured. The flame sensing system also includes a flame current detector to measure the flame current and generate an output voltage corresponding to the flame current, and a first level detector to generate a flame strength output signal based on the output voltage, where the flame strength output signal is indicative of a strength of a flame.

A water heater may include a water tank, a burner, a pilot for igniting the burner, an ignitor for igniting the pilot, a thermoelectric device in thermal communication with a flame of the pilot, a controller for controlling an ignition sequence of the pilot using the ignitor, and a rechargeable power storage device for supplying power to the ignitor and the controller. The rechargeable power storage device may be rechargeable using the energy produced by the thermoelectric device. The controller is configured to selectively run only the pilot for at least part of a heating cycle to increase the recharge time of the rechargeable power storage device while still heating the water in the water heater.

A method for combustion tuning, comprises collecting exhaust parameters indicating combustion status of a boiler by a sensor array; determining whether the exhaust parameters of the boiler match a preset optimization target; and optimizing combustion, if the exhaust parameters do not match the preset optimization target by selecting a model from a model repository based on a current boiler condition, wherein the model corresponds to a relationship between model input variables and the exhaust parameters; determining at least one optimized model input variable of the boiler for realizing the optimization target, based on the selected model; and adjusting actuators of the boiler according to the optimized model input variable.

A burner includes a flame sensor configured to detect at least one of permittivity, capacitance, or resistance across a flame region. The permittivity, capacitance, or resistance is used to determine the presence or absence of the flame in a combustion system. A combustion system supports a combustion reaction. The combustion system utilizes a combustion sensor, and optionally a plasma generator to stabilize the combustion reaction. A controller receives sensor signals from the combustion sensor and controls the plasma generator to stabilize the combustion reaction responsive to the sensor signals. The plasma generator stabilizes the combustion reaction by generating a plasma.

A system for measuring a fuel-oxidant equivalence ratio includes at least one wall defining a gas volume including fuel and air. A gas ionization source is configured to cause a formation of ions in the gas. A power supply is configured to output a time-varying voltage. A first electrode is disposed in the gas volume, operatively coupled to the power supply, and configured to carry the time-varying voltage. A second electrode is arranged to operatively couple to a signal output by the first electrode after the signal passes through the gas volume. Characteristics of the received signal indicate the fuel-oxidant equivalence ratio.

A gas powered water heater includes a storage tank, a main burner, a flame sensor assembly, and a controller communicatively coupled to the flame sensor assembly. The flame sensor assembly includes a probe positioned proximate the main burner to couple an electric current to the main burner through a flame on the main burner and not to couple an electric current to the main burner when the flame is not present on the main burner, and a detector that provides signals representative of the electric current provided through the probe. The controller is programmed to determine a length of time taken for a transition between a signal representative of no electric current and a signal representative of a steady state electric current, and determine, based at least in part on the determined length of time, a strength of the flame on the main burner.

A system for controlling a combustion appliance based on one or more localized environmental factors and an inlet/exhaust system enclosed within a single enclosure. The control system includes an electrically controlled fuel valve, coupled to a source of combustion appliance fuel, and responsive to a fuel valve control signal, for controlling the flow of fuel to the appliance. An air pressure detector is disposed in an area proximate the combustion appliance and configured for detecting negative air pressure in the proximate area and in response for providing a negative air pressure detection signal to a relay which will deactivate the fuel valve until negative air pressure is not present thereby preventing operation of the combustion appliance. Further, if negative air pressure is detected, the relay energizers a makeup air device to bring an outside air into the area near the combustion appliance.

A method of controlling the temperature within a heating apparatus for eliminating or reducing combustion resonance, the method including measuring a temperature of the burner assembly; comparing the measured temperature with a predetermined temperature limit or range; determining whether the measured temperature is greater than a predetermined temperature limit or range; performing a controlled action if the measured temperature is greater than the predetermined temperature limit or range.

A combustible gas heating apparatus includes: a main burner arranged in a combustion chamber of the apparatus, a pilot burner for generating a pilot flame for igniting it, a valve group comprising a main valve arranged on a main duct, and a pilot valve arranged thereon, upstream of the main valve, for supplying gas to the pilot burner, a system for controlling gas to the main and pilot burners, including an electronic control unit operatively associated with the main and pilot valves, a thermal safety device actuable in the presence of inflammable vapors near the apparatus, to safely extinguish the main burner when a predetermined temperature threshold has been exceeded, the pilot burner configured as a continuous pilot burner having a permanent flame, the pilot and main valves being electrically-operated valves, an auxiliary buffer battery configured to power the electronic control.