A modulating burner apparatus includes a burner and a blower placed upstream of the burner. A venturi is placed upstream of the blower. A damper valve is placed upstream of the venturi. The damper valve has an open position and a restricted position. A smaller gas valve and a larger gas valve are communicated with the venturi. A controller is operably associated with the system to select a position of the damper valve and to select the appropriate one of the gas valves so as to provide a low output operation mode and a high output operation mode, which in combination provide an overall turndown ratio of at least 25:1.

A modulating burner apparatus includes a burner and a blower placed upstream of the burner. A venturi is placed upstream of the blower. A damper valve is placed upstream of the venturi. The damper valve has an open position and a restricted position. A smaller gas valve and a larger gas valve are communicated with the venturi. A controller is operably associated with the system to select a position of the damper valve and to select the appropriate one of the gas valves so as to provide a low output operation mode and a high output operation mode, which in combination provide an overall turndown ratio of at least 25:1.

The disclosed technology includes a device for extending the turndown ratio of a gas-fired burner system. The device can comprise a variable area device configured reduce the amount of fuel and air passed to the burner during low output conditions by adjusting the cross-sectional area of the passage between the blower and the burner. The variable area device can be controlled by an actuator that adjusts the position of the variable area device. The actuator can be manually controlled, mechanically controlled, or electronically controlled.

The disclosed technology includes a device for extending the turndown ratio of a gas-fired burner system. The device can comprise a variable area device configured reduce the amount of fuel and air passed to the burner during low output conditions by adjusting the cross-sectional area of the passage between the blower and the burner. The variable area device can be controlled by an actuator that adjusts the position of the variable area device. The actuator can be manually controlled, mechanically controlled, or electronically controlled.

A method of improving natural draft fire tube burner efficiency by controlling combustion air flow. The method involves positioning in a fire tube an air damper body comprising a fixed plate having a plurality of air flow openings and a rotatable plate having a plurality of air flow openings. Air flow through the air damper body is controlled by adjusting the relative rotational position of the fixed plate and the rotatable plate. The air damper body has an air inlet face, an air outlet face, and an outer circumference. The method involves establishing and maintaining a relationship between an air damper open area, firing rate and excess air to maintain stack oxygen below 3% in accordance with a formula A2+A3<DRFRA1.

An air intake control assembly for adjusting an air intake into a combustion chamber of a solid fuel burning appliance is provided. The air intake control assembly comprises a mounting structure having at least one air intake opening, a shutter mounted to the mounting structure and configurable between an open configuration and an at least partially closed configuration, a power supply, a motor operatively connected to the shutter and activable to modify a configuration of the shutter with respect to the at least one air intake opening, a temperature sensor electrically connected to the motor and the power supply to monitor a temperature representative of a temperature of the combustion chamber; and an electric circuit connecting the motor to the power supply and being operatively connected the temperature sensor. A solid fuel burning appliance and a method for controlling an air intake into a combustion chamber of a solid fuel burning appliance are also provided.

A modulating burner apparatus includes a burner and a blower placed upstream of the burner. A venturi is placed upstream of the blower. A damper valve is placed upstream of the venturi. The damper valve has an open position and a restricted position. A smaller gas valve and a larger gas valve are communicated with the venturi. A controller is operably associated with the system to select a position of the damper valve and to select the appropriate one of the gas valves so as to provide a low output operation mode and a high output operation mode, which in combination provide an overall turndown ratio of at least 25:1.

A modulating burner apparatus includes a burner and a blower placed upstream of the burner. A venturi is placed upstream of the blower. A damper valve is placed upstream of the venturi. The damper valve has an open position and a restricted position. A smaller gas valve and a larger gas valve are communicated with the venturi. A controller is operably associated with the system to select a position of the damper valve and to select the appropriate one of the gas valves so as to provide a low output operation mode and a high output operation mode, which in combination provide an overall turndown ratio of at least 25:1.