A gas burner includes a burner body that defines a plurality of forced induction flame ports. An air outlet orifice is mounted to an injet body at an outlet of an air passage such that the air outlet orifice is oriented for directing a flow of air towards the plurality of forced induction flame ports. A gas outlet orifice is mounted to the injet body at an outlet of a gas passage such that the gas outlet orifice is oriented for directing a flow of gaseous fuel towards the plurality of forced induction flame ports. A pneumatically actuated gas valve is positioned within the injet body. The pneumatically actuated gas valve is configured to adjust from a closed configuration to an open configuration in response to the flow of air through the air passage.

A throttle arrangement comprising at least one first throttle element and at least one second throttle element, wherein the first throttle element and the second throttle element are connected in series, wherein the first throttle element has a first pressure loss coefficient which correlates positively with a volume flow passing through the throttle arrangement, and the second throttle element has a second pressure loss coefficient which correlates negatively with the volume flow passing through the throttle arrangement.

Systems and methods are described related to a premix combustion system used in a furnace system. Prior systems have to create a negative pressure in the premix chamber to draw gas into the chamber. Embodiments under the current disclosure can use an amplifier that is pneumatically coupled to an air supply and a secondary location (besides the gas valve). Coupling to the amplifier to a location apart from the gas valve allows the system to avoid a negative pressure in the mixing chamber. The amplifier can apply an amplified pressure or signal to a gas valve regulator and thereby raise the gas pressure so that the gas supply is driven into the premix chamber.

A gas burner assembly for a cooktop appliance includes a normally aspirated primary burner and a concentrically-positioned forced air boost burner. A dual-outlet control valve provides a flow of primary fuel to the primary burner through a first outlet and a flow of boost fuel to the boost burner through a second outlet. The boost burner operates by receiving the flow of boost fuel and a flow of combustion air from a forced air supply source only when the primary burner is operating in a low condition.

The premixing device includes a first and a second venturis having a pressure reducing portion for air, and a gas supply passage for supplying fuel gas to the venturis, and generates air-fuel mixture by mixing fuel gas with air flowing in the venturis by using a fan and supplies the air-fuel mixture to a burner. A first and a second nozzles for reducing pressure of fuel gas are disposed in the gas supply passage, and the first and the second nozzles are formed in the same nozzle shape as the pressure reducing portion of the first and the second venturis.

Partially-premixed gas burner appliance (10), comprising a combustion chamber (11), a fan (17) and a gas modulator (20). The fan (17) is configured to provide an air flow to the combustion chamber (11) and is assigned to an air inlet port (11A) of the combustion chamber or to an air duct (18) configured to provide the air to the air inlet port. An air flow restriction element (19) is assigned to the air inlet port (11A) or to the air duct (18). The air flow restriction element (19) is configured to provide a pressure drop so that the pressure downstream of the air flow restriction element (19) is lower than the pressure upstream of the same. The gas modulator (20) is configured to provide a gas flow to the combustion chamber (11), wherein a first portion of the air provided by the fan (17) is premixed with the gas flow before the gas is combusted, and wherein a second portion of the air provided by the fan (17) is mixed with the gas while the gas is combusted. The gas modulator (20) is a pneumatic gas control valve, wherein the pneumatic gas control valve has a main gas valve (22), a safety gas valve (23), a servo gas valve (24) and gas outlet pres-sure regulator (25). The gas outlet pressure regulator (25), namely a first chamber (33) of the same in which a pressure is present that influences the nominal-value of the gas outlet pressure of the pneumatic gas control valve, is connected to the air inlet port (11A) or to the air duct (18) upstream of the air flow restriction element (19) such that the gas outlet pressure provided by the pneumatic gas control valve de-pends on the air pressure upstream of the air flow restriction element (19).

A method of premixing apparatus for missing fuel gas with air to supply thus obtained air-fuel mixture, through a fan to a burner, includes at a time of changing over to a small-capacity state in which a first ventilation resistance in an air supply passage is increased and also in which a second ventilation resistance in a gas supply passage is increased, rotating a butterfly valve down to a closing side stop angle; and at a time of changing over to a large-capacity state in which the first ventilation resistance in the air supply passage is decreased and also in which the second ventilation resistance in the gas supply passage is decreased, rotating the butterfly valve up to an open-side stop angle.

A combustion apparatus having: an upstream-side air supply chamber and a downstream-side mixing passage, both being respectively interposed between a fan and a burner; and a zero governor which is interposed in a gas supply passage and which adjusts a secondary gas pressure to a pressure equivalent to an internal pressure in the air supply chamber, thereby enabling to maximize a turndown ratio to the extent possible. The combustion apparatus has: first and second, totally two, mixing passages; a first gas outlet which is in communication with a narrowed part of the first mixing passage; a second gas outlet which is in communication with a narrowed part of the second mixing passage; a first air valve which varies an opening degree of an air inlet of the first mixing passage; a second air valve which varies an opening degree of an air inlet of the second mixing passage; and a gas valve.

A fuel-operated vehicle heater includes a burner area (12) with a combustion chamber (14); a fuel pump (24); and a combustion air blower (28). A pressure sensor (38) detects a feed back pressure. An actuating unit (36) actuates the fuel pump (24) with a predefined value of a pump operating variable, and actuates the combustion air blower with a predefined value of a blower operating variable. A heater process includes detecting the feed back pressure in case of a feed operating state set during the combustion operation and comparing the detected feed back pressure (P.sub.e) with an expected feed back pressure (P.sub.E) for the set feed operating state. If the detected feed back pressure deviates from the expected feed back pressure the pump operating variable is changed such that the feed back pressure changes toward the expected feed pressure and/or essentially corresponds to the expected feed back pressure.

Provided is a dual venturi for a combustion apparatus that is capable of effectively controlling calorific power since the amount of gas for a burner provided in a water heater and the amount of supplied air are controlled in two phases, and a motor and a damper are coupled to each other so that the damper opens or blocks inlets for secondary air and the gas at the same time that the damper is rotated by the driving of the motor.