The Lochinvar & A.O. Smith VAL3403 Gas Valve is a critical control component designed to regulate the flow of gas in compatible boilers, water heaters, and other gas-fired HVAC equipment. It works by opening, closing, and modulating gas supply based on signals from the system’s control board, ensuring safe and efficient combustion. This gas valve helps maintain accurate fuel delivery,... https://www.partshnc.com/val3403-lochinvar-ao-smith-valve-gas-100172016-vr8303m4897