Watts FV-4M1-1/8 Automatic Vent Valve, 1/8"Provide automatic air venting for hot or cold water distribution systems. These vents purge air that may be in the water system. The vent valve utilizes a float to actuate the valve plug which is located at the top of the valve. Once the air is displaced and the system pressure is sustained, the valve plug seals and prevents any water from escaping from the system. The float vent can also operate as an anti vacuum device since it will permit air to