Honeywell Gas valve VK4105A2025U

The Honeywell VK4105A2025U is a combined gas valve used in burner ignition control systems, providing gas flow control for pilot and main burners. It includes a gas solenoid valve and an ignition regulator, featuring regulation of the gas-air mixture in a 1:1 ratio. The valve operates with a nominal inlet pressure of 25 millibars and is designed for upright installation. It has a diaphragm diameter of 2.8 millimeters and inlet/outlet connections of 18.6 millimeters via flanges.

Parts of this type are selected by matching the valve's connection size, inlet pressure rating, and electrical specifications to the burner system. Installation typically requires upright mounting and connection to the gas supply and burner manifold. Ensure the valve's flange dimensions and pilot gas connection (4 mm) align with the existing setup. Verify the voltage compatibility with the ignition regulator, as some models may not support 24V operation.

Common failures include the main valve failing to open or close properly, leading to no gas flow or uncontrolled gas flow. Symptoms may include burner ignition failure, flame instability, or pressure fluctuations. Check for clogged inlet filters, electrical connection issues, or servo controller malfunctions. If the valve does not respond to control signals, test the solenoid and pressure regulation components.