Honeywell 45900444B-001B venturi

The venturi manifold is a gas/air mixing unit that allows modulation of a premix burner with constant gas/air ratio down to 20% of maximum load. It is to be used in combination with a fan and a Honeywell 1:1 regulating gas valve. The modulation is accomplished by changing the fan speed. The outlet pressure of the gas valve is regulated to ambient pressure by the gas valve. The venturi generates a negative pressure against ambient by which the gas is drawn through the gas valve outlet. The venturi manifold system is designed to be fitted in up to eight positions on a specially adapted DC fan, using two supplied M5 thread forming screws. The venturi manifold is sealed with a gasket that is supplied with the assembly. The gas valve can be fitted directly on the manifold assembly in horizontal and vertical position with both the side outlet and the end outlet. Four M4 screws and a special NBR gasket are used for the end outlet version. Three M5 screws and a special sealing ring are used for the side outlet version. The venturi manifold can be trimmed to the correct gas/air ratio by turning the throttle screw