A premixing device includes: a gas flow path for allowing air to flow; a gas outlet that allows fuel gas to flow out into the gas flow path by utilizing a negative pressure; and a flapper disposed in the gas flow path. The premixing device further includes an operation regulating part for the flapper which allows the opening degree of the flapper to change according to the air flow rate in a range below a predetermined upper limit position while preventing the flapper from rotating in an opening direction beyond the upper limit position. The operation regulating part is capable of selectively switching and setting one of a first upper limit position for normal combustion and a second upper limit position for fuel ignition. The opening degree of the flapper at the second upper limit position is smaller than that at the first upper limit position.

A premixing device includes: a gas flow path for allowing air to flow; a gas outlet that allows fuel gas to flow out into the gas flow path by utilizing a negative pressure; and a flapper disposed in the gas flow path. The premixing device further includes an operation regulating part for the flapper which allows the opening degree of the flapper to change according to the air flow rate in a range below a predetermined upper limit position while preventing the flapper from rotating in an opening direction beyond the upper limit position. The operation regulating part is capable of selectively switching and setting one of a first upper limit position for normal combustion and a second upper limit position for fuel ignition. The opening degree of the flapper at the second upper limit position is smaller than that at the first upper limit position.

A method for commissioning a gas valve assembly for controlling fuel flow to a combustion appliance. An example method for commissioning the gas valve assembly may include initiating a commissioning mode in the controller of the gas valve assembly. Once in the commissioning mode, inputting a user defined initial air to fuel (A/F) ratio, activating the combustion appliance, setting a burner load of the combustion appliance to a set burner load, inputting a desired A/F ratio for the set burner load, running the combustion appliance at the burner load with the desired A/F ratio, and observing the operation of the combustion appliance. The method may further include saving the desired A/F ratio for the set burner load to the controller of the gas valve assembly and exiting the commissioning mode.

A method for commissioning a gas valve assembly for controlling fuel flow to a combustion appliance. An example method for commissioning the gas valve assembly may include initiating a commissioning mode in the controller of the gas valve assembly. Once in the commissioning mode, inputting a user defined initial air to fuel (A/F) ratio, activating the combustion appliance, setting a burner load of the combustion appliance to a set burner load, inputting a desired A/F ratio for the set burner load, running the combustion appliance at the burner load with the desired A/F ratio, and observing the operation of the combustion appliance. The method may further include saving the desired A/F ratio for the set burner load to the controller of the gas valve assembly and exiting the commissioning mode.

In a premixing apparatus that mixes a fuel gas with air, supplies an air-fuel mixture to a burner through a fan, and carries out a control that regulates an opening degree of a variable throttle valve, which is interposed in a gas supply passage, so that an excess air ratio of an air-fuel mixture becomes an appropriate value, in a case where a detected excess air ratio deviates to one side, e.g., a large side, from an acceptable range, a motor is repeatedly caused to rotate by a unit-angle in an opening-degree increasing direction until the detected excess air ratio becomes an appropriate value. In a case where the detected air ratio deviates to the other side, e.g., a small side, from the acceptable range, the motor is caused to rotate, at a high speed in an opening-degree decreasing direction, till a first position that is anticipated that the excess air ratio will become a value that deviates by a fixed quantity from the acceptable range to a large side, thereafter, the motor is caused to rotate, at the high speed in an opening-degree increasing direction, till a second position that is a short of a target position, and subsequently, the motor is caused to rotate by the unit-angle in the opening-increasing direction.

In a premixing apparatus that mixes a fuel gas with air, supplies an air-fuel mixture to a burner through a fan, and carries out a control that regulates an opening degree of a variable throttle valve, which is interposed in a gas supply passage, so that an excess air ratio of an air-fuel mixture becomes an appropriate value, in a case where a detected excess air ratio deviates to one side, e.g., a large side, from an acceptable range, a motor is repeatedly caused to rotate by a unit-angle in an opening-degree increasing direction until the detected excess air ratio becomes an appropriate value. In a case where the detected air ratio deviates to the other side, e.g., a small side, from the acceptable range, the motor is caused to rotate, at a high speed in an opening-degree decreasing direction, till a first position that is anticipated that the excess air ratio will become a value that deviates by a fixed quantity from the acceptable range to a large side, thereafter, the motor is caused to rotate, at the high speed in an opening-degree increasing direction, till a second position that is a short of a target position, and subsequently, the motor is caused to rotate by the unit-angle in the opening-increasing direction.

A piston rod seal unit. The piston rod seal unit includes a housing, a cylinder gland, and at least one floating rod seal assembly mounted in the cylinder gland, the floating rod seal assembly comprising at least one rod seal mounted onto the floating rod seal assembly.

A piston rod seal unit. The piston rod seal unit includes a housing, a cylinder gland, and at least one floating rod seal assembly mounted in the cylinder gland, the floating rod seal assembly comprising at least one rod seal mounted onto the floating rod seal assembly.

A fuel nozzle assembly includes one or more tapered fuel nozzles. Each tapered fuel nozzle includes an acute trailing edge or tip at a top portion of the fuel nozzle. One or more fuel orifices are arranged proximate the acute trailing edge or tip. A tapered fuel nozzle having a toroidal airfoil structure includes a fuel channel to distribute a fuel to the fuel orifice(s). The fuel nozzle assembly may be provided as part of a burner system, including a perforated flame holder, and associated method, in which the fuel nozzle assembly is oriented to direct fuel form the fuel orifices toward the perforated flame holder.

A fuel nozzle assembly includes one or more tapered fuel nozzles. Each tapered fuel nozzle includes an acute trailing edge or tip at a top portion of the fuel nozzle. One or more fuel orifices are arranged proximate the acute trailing edge or tip. A tapered fuel nozzle having a toroidal airfoil structure includes a fuel channel to distribute a fuel to the fuel orifice(s). The fuel nozzle assembly may be provided as part of a burner system, including a perforated flame holder, and associated method, in which the fuel nozzle assembly is oriented to direct fuel form the fuel orifices toward the perforated flame holder.