A method of calibrating a furnace includes determining a first flame stabilization period for the furnace that avoids detachment of a flame from a burner within a burner box of the furnace, determining a second flame stabilization period that is longer than the first flame stabilization period and avoids emission of a combustion tone from the furnace, and configuring a controller of the same or another furnace to utilize a flame stabilization period that has a duration between the first and second flame stabilization periods. Each flame stabilization period commences upon ignition of a premixed mixture of air and fuel at the burner while an inducer fan operates within a first range of fan speeds, and terminates when the rotational speed of the inducer fan increases to a second range speeds that is greater than the entire first range.

A method for controlling a combustion apparatus having a combustion state in which a parameter related to the combustion state reflects a chaotic behavior is provided. The method includes the steps of measuring the parameter and determining a time series of the parameter, shifting the time series by a variable time delay for determining a time-shifted signal, and forming a difference between the time-shifted signal and the time series for determining a time dependent first signal, so that a norm of the difference is lowest. A time dependent second signal is determined, wherein determining the time dependent second signal includes at least one of using a frequency of a desired oscillating combustion state, and shifting the time series by a set time delay. The first signal and the second signal are combined to determine a control signal. The control signal is used to influence the combustion apparatus.

Provided is a correlation deriving method including the steps of: generating coal ash by incinerating coal; generating sintered ash by heating the coal ash at a predetermined heating temperature within a range of a combustion temperature of a coal burning boiler; measuring hardness of the sintered ash; measuring an exhaust gas temperature exhibited when coal which is to have the hardness is burnt in the coal burning boiler; and deriving a correlation between the hardness and the exhaust gas temperature.

A gas cooktop may include: a gas burner; a sensor configured to sense temperature of a cooking container heated by the gas burner; a valve configured to control flow rate of gas from a gas source to the gas burner; and a control system including circuitry. The control system may start operation of the gas burner; receive sensor signals from the sensor indicating the temperature of the cooking container; and based on received sensor signals representing the sensed temperature of the cooking container and a cooking profile indicating one or more durations and one or more temperatures, control the valve to change the gas flow rate to the gas burner.

A gas cooktop may include: a gas burner; a sensor configured to sense temperature of a cooking container heated by the gas burner; a valve configured to control flow rate of gas from a gas source to the gas burner; and a control system including circuitry. The control system may start operation of the gas burner; receive sensor signals from the sensor indicating the temperature of the cooking container; and based on received sensor signals representing the sensed temperature of the cooking container and a cooking profile indicating one or more durations and one or more temperatures, control the valve to change the gas flow rate to the gas burner.

A temperature display and/or control system is disclosed for a cooing apparatus, such as a grill, comprising a plurality of individual zones to provide individual zone temperatures. Each zone of the grill is associated with a temperature sensor, such as a thermocouple, and a visual indicator to indicate the zone temperature, such as control knob bearing a multi-color LED. A controller obtains a signal from the temperature sensor indicating a raw temperature and converts the raw temperature to an actual zone temperature based on a temperature profile selected for the zone. The temperature profile is configurable for each zone based on a configuration of the zone in order to maintain an accurate temperature conversion despite alterations to an environment.

Cooktop appliances are provided. A cooktop appliance can include a gas burner; a manifold having a gas input; a primary line extending between the manifold and the gas burner, wherein the primary line operates as a non-modulated minimum gas flow line when the cooktop appliance is in an automatic mode; a secondary line extending between the manifold and the gas burner, wherein a gas flow rate of the secondary line is controllable by a flow control valve; a primary valve in fluid communication with at least the primary line; and a control system including: a sensor configured to detect a temperature corresponding to the gas burner; and a controller regulating: (i) the flow control valve in response to the detected temperature to achieve a desired temperature, and (ii) the primary valve when the flow control valve is closed and the detected temperature exceeds the desired temperature.

Cooktop appliances are provided. A cooktop appliance can include a manifold having a gas input; a first burner in fluid communication with the manifold through a first burner supply line having a first valve; and a second burner in fluid communication with the manifold through a second burner supply line having a second valve, the second burner arranged coaxially with respect to the first burner, wherein the second burner supply line comprises a primary line, a secondary line, and a sum line, the sum line providing a combined flow of gas from the primary line and the secondary line to the second burner, wherein the secondary line of the second burner comprises a third valve.

Cooktop appliances are provided. A cooktop appliance can include a gas burner; a manifold having a gas input; a primary line extending between the manifold and the gas burner, wherein a gas flow rate in the primary line is controllable by a user selectable interface; and a secondary line extending between the manifold and the gas burner, wherein a gas flow rate in the secondary line is controllable by a flow control valve.

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.