The Bosch HVAC 87161064450 Air Vent Valve is an OEM automatic air-venting component used in compatible Bosch Greenstar and Condens 5000W boilers. Installed in the pump or primary hydraulic circuit, it uses a float mechanism to detect and release trapped air while automatically resealing when water reaches the valve. This helps prevent airlocks, circulation problems, and unwanted syste... https://www.partshnc.com/bosch-hvac-87161064450-air-vent-valve