The Viessmann 7855594 Gas Valve GB-ND 055 E01 is a precision gas-control component designed to regulate the supply of fuel gas to compatible heating equipment. It works by controlling and maintaining the appropriate gas flow and pressure to the burner, supporting safe and consistent combustion during operation. This gas valve is used in compatible Viessmann gas-fired boilers and heati... https://www.partshnc.com/viessmann-7855594-gas-valve-gb-nd-055-e01