Honeywell Venturi tube VMU335A1000

This venturi tube is designed for premix gas burners. It maintains a fixed 1:1 gas-air ratio and allows the burner to be modulated down to 17% of its maximum load. Smooth modulation is achieved by changing the fan speed. It is rated for a nominal capacity of 335 kW and is intended for use with a fan and a gas regulating valve that provides the same gas-air ratio.

Venturi tubes of this type are selected primarily by their rated output in relation to the burner's maximum power, as well as the gas family and the required pressure differential between the gas valve outlet and the combustion head. The connection dimensions and flange interface must match the existing gas train. Before ordering, compare the internal geometry and any incorporated gas orifice with the original part, and plan to replace the gasket or O-ring seals together with the venturi.

A failed or mismatched venturi alters the air-to-fuel ratio, typically causing incomplete combustion, flame instability, or excessive emissions. The burner may struggle to modulate smoothly or fail to reach full load. Check the venturi for carbon deposits, corrosion, or physical damage; internal blockages reduce gas flow and upset the fuel-air balance.