The Bosch HVAC 87085002890 Water Valve Selector Screw is a replacement adjustment component used with compatible Bosch hydronic heating equipment. It works with the water valve assembly to help set or maintain the required valve position for proper water flow through the system. This component is commonly used in compatible Bosch boilers and hydronic HVAC systems. Its precise fit supp... https://www.partshnc.com/bosch-hvac-87085002890-water-valve-selector-screw