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.

Method for operating a gas burner appliance (10) comprising: a combustion chamber (11), an ignition device (27), a fan (14), a gas safety valve unit (19) assigned to the gas duct (16), an electric gas flow modulator (18) assigned to the gas duct (16), a sensor (21) positioned between the gas safety valve unit (19) and the gas flow modulator (18), wherein the gas burner appliance (10) is operated to determine the gas family of the gas of the gas/air mixture by the following steps: Before the gas burner appliance becomes started measuring the ambient air pressure by the sensor (21), wherein the ambient air pressure is measured when the safety valve unit (19) is closed, the gas flow modulator (18) is opened and the fan (14) is stopped. When the gas burner appliance (10) becomes started running the fan (14) at a defined fan speed, increasing the opening of the gas flow modulator (18) while activating the ignition device (27) trying to ignite the gas/air mixture until the activation of ignition device results into a combustion of the gas/air mixture. Determining from the fan speed of the fan (14) and from the measured ambient air pressure an air volume flow. Measuring the gas pressure by the sensor (21) when the safety valve unit (19) is opened, the gas flow modulator (18) is opened and the fan (14) is running. Determining from the opening of the gas flow modulator (18) at which the combustion started and from the measured gas pressure a gas volume flow. Determining a ratio between the gas volume flow and the air volume and from said ratio the gas family of the combusted gas.

A device for mixing combustible gas and combustion air, hot water installation, and corresponding thermal mass flow sensor and method. The device includes an air line, a gas line with a control valve, a first measuring line connecting the air and gas lines, and a second measuring line connecting the first measuring line to the gas and/or air line, forming a three-way intersection. A thermal mass flow sensor includes first and second temperature sensors in the first measuring line, positioned respectively in a gas flow between the three-way intersection and the air line and in a gas flow between the three-way intersection and the gas line. A controller controls the control valve based on a difference, measured by the flow sensor, between mass flow rate of gas between the three-way intersection and the air line and mass flow rate of gas between the three-way intersection and the gas line.

A fuel supply system for a gas burner assembly. The gas burner assembly includes an inner burner stage positioned concentrically within an outer burner stage. The fuel supply system includes a fuel supply for providing a primary flow of fuel through a primary fuel conduit and a single outlet control valve operably coupled to the primary fuel conduit. A first and second fuel supply conduit split off of the primary fuel conduit and are fluidly coupled with the outer burner stage and the inner burner stage, respectively. A shutoff valve is operably coupled to one of the first fuel supply conduit and the second fuel supply conduit and is configured for closing when a flow rate of fuel through the shutoff valve drops below a predetermined flow rate.

A system and controller where the pressure of the air is continuously monitored or read at a designated exhaust point and adjustments made to the flow of the air and gas to keep the efficiency of the appliance at a maximum to control the appliance (or the burner for an appliance) within specifications as dictated by the customer or consumer rather than training the user.

A system for controlling activity in a combustion chamber. The system does not necessarily need to be mechanically adjusted and yet may provide precise control of a fuel air mixture ratio. A sensing module of the system may have a mass flow sensor that relates to air flow and another sensor that relates to fuel flow. Neither sensor may need contact with fuel. Fuel and air to the system may be controlled. Pressure of the fuel and/or air may be regulated. The sensors may provide signals to a processor to indicate a state of the fuel and air in the system. The processor, with reliance on a programmed curve, table or the like, often based on data, in a storage memory, may regulate the flow or pressure of the fuel and air in a parallel fashion to provide an appropriate fuel-air mixture to the combustion chamber.

A gas appliance includes a burner, a gas valve, and a control device, wherein the gas valve includes a valve body, a flow regulator, a hot film anemometer, and a stepper motor. The valve body communicates with the burner and a gas source. The flow regulator is driven by the stepper motor to change a gas flow rate supplying to the burner. The hot film anemometer is disposed in the valve body and includes a probe exposed to the outlet passage. The control device executes a control method for the gas valve: sensing the gas flow rate in the outlet passage with the hot film anemometer; comparing the gas flow rate sensed by the hot film anemometer with a predetermined gas flow rate, and controlling the stepper motor to drive the flow regulator based on the comparison result, whereby to stabilize the gas flow rate.

A fuel-fired device can include an air-moving device that mixes air and a fuel to generate a fuel-air mixture. The fuel-fired device can also include an air box that provides the air to the air-moving device, and a fuel valve that provides the fuel to the air-moving device, where the fuel valve includes a tracking port coupled to the air box, where the tracking port detects a pressure of the air box. The fuel-fired device can further provide a pressure-regulating device disposed between a pressurized component and the tracking port of the fuel valve. The flow regulating device can control, during an ignition phase of operation, an amount of the fuel provided by the fuel valve to the air-moving device.

The present disclosure deals with the measurement of flows of a fluid in a combustion device. In particular embodiments, the teachings may be employed in the measurement of flows of fluids such as air in the presence of turbulence. For example, a combustion device may include: a burner; a side duct; and a feed duct. The side duct may include a mass flow sensor and a flow resistance element. The mass flow sensor detects a mass flow through the side duct. The flow resistance element subdivides the side duct. A connector of the feed duct comprises a Pitot probe. A first section of the Pitot probe projects into the feed duct and a sub area facing towards the outlet of the feed duct of the first section of the Pitot probe comprises the inlet of the Pitot probe.

A high-efficiency modulating gas furnace (herein gas furnace) includes a furnace controller. The gas furnace further includes a gas valve and at least one pressure switch that is coupled to the furnace controller. The electrical contacts of the at least one pressure switch are removed from a series electrical circuit with the gas valve such that the gas furnace operates without de-energizing the gas valve as soon as the electrical contacts of the at least one pressure switch are opened. Further, the furnace controller operates the induced draft blower at or close to a lowest RPM at which the electrical contacts of the at least one pressure switch can be kept closed, which is between a make point RPM at which the electrical contacts of the at least one pressure switch close and a break point RPM at which the electrical contacts of the at least one pressure switch open.