Honeywell Venturi tube VMU680A1009

The Honeywell VMU680A1009 is a venturi tube designed for premix gas burners, with a modulation range of 17–100% and a gas/air ratio of 1:1. It has a capacity of 680 gallons per hour, corresponding to a maximum burner output of 680 kW. This component creates a controlled pressure drop to draw gas into the air stream, ensuring proper mixing before combustion. It is used in applications where air and gas are premixed prior to the burner head.

Venturi tubes of this type are selected based on the burner's maximum output and the required gas pressure differential. When replacing, ensure the venturi's capacity matches the burner's rating and that the mounting gasket or O-ring is in good condition. The venturi must be oriented correctly relative to the gas inlet and burner head, with connecting pipes aligned without stress to prevent leaks or vibration. If the gas valve or fan is changed, re-confirm the venturi selection against the new components' pressure and flow characteristics.

Common failure modes include clogging or damage from debris, leading to unstable air-fuel mixing and poor combustion. Symptoms may include flame instability, incomplete combustion, or difficulty maintaining modulation. Check for blockages, cracks, or warping, and ensure the venturi is clean and properly sealed.