Honeywell Gas valve VK4100C1026U

The Honeywell VK4100C1026U is a combined gas valve designed for burner control and ignition systems, integrating safety and regulation functions for both pilot and main burners. It features regulation of the gas-air mixture in a 1:1 ratio, smooth ignition via Softlite technology, and operates with an ambient temperature range of -15 to 60 °C. The valve has a maximum working pressure of 45 mbar, an inlet pressure maximum of 60 mbar, and a nominal inlet pressure of 25 mbar. It includes a compression fitting of 4 mm, a pilot gas connection diameter of 4 mm, and an inlet/outlet diameter of 18.6 mm. The valve's output aperture is 2.8 mm, with a Softlite pressure of 5 mbar and a Softlite time of 1.5 seconds, and it has a pressure drop of 3 mbar.

When selecting a replacement gas valve of this type, ensure the connection thread (1/2" BSP.PL) matches the existing piping, and verify the inlet and outlet diameters (18.6 mm) align with the burner manifold. The valve must be compatible with the control system's voltage and ignition regulator type, as some models require specific connectors or rectifier units. Check the ambient temperature range and maximum inlet pressure (60 mbar) to ensure they meet the installation environment's requirements. The valve can be mounted upright, and pressure measurement fittings may require silicone tubes of 4 or 6 mm diameter.

Common failures in gas valves of this kind include the main valve failing to open or close properly, leading to no gas flow or continuous gas flow even when the burner is off. Symptoms may include the burner not igniting, flame instability, or the system shutting down due to safety lockouts. Check for blockages in the inlet filter, verify the servo pressure regulation, and test the electrical connections to the valve and ignition regulator. If the valve leaks, it may cause gas odor or pressure drops, requiring immediate inspection.