Watts Brass Tubular FV-4M1 1/8 Automatic Air Vent Valve

Product Description

The WATTS BRASS TUBULAR FV-4M1 1/8 is an automatic air vent valve designed for hydronic boiler piping systems. It continuously vents trapped air from system water, preventing air pockets from collecting in the loop and causing circulation loss or noise. The valve uses a float mechanism to actuate the valve plug, opening to release air and closing as water rises. It also functions as an anti-vacuum device, protecting the system against negative pressure conditions. Rated for a maximum working temperature of 240 degrees F and a maximum working pressure of 150 psi, this valve suits residential and light commercial hot water heating applications. Licensed plumbers and hydronic heating technicians are the typical installers.

This valve is used in boiler piping systems where automatic, continuous air removal is required. It is suited for residential and commercial hydronic heating installations where manual bleeding is impractical or insufficient. The 1/8 inch male pipe thread connection allows direct installation into standard tapping points on boiler headers, distribution manifolds, and high-point piping locations. The float-actuated design requires no manual intervention during normal system operation, making it appropriate for systems that cycle frequently.

Key Features

• Automatically and continuously vents air from hydronic system water without manual operation
• Float-actuated valve plug opens to release air and closes on water contact
• Functions as an anti-vacuum device to prevent negative pressure damage
• Maximum working temperature of 240 degrees F for hot water boiler compatibility
• Maximum working pressure of 150 psi
• 1/8 inch male pipe thread connection for standard boiler and manifold tapping points

Compatibility

Designed as an OEM-style replacement or new-installation automatic air vent for residential and light commercial hydronic boiler piping systems using 1/8 inch male pipe thread connections.

Installation Notes

Installation is typically performed by a licensed plumber or hydronic heating technician. Shut down the boiler and relieve system pressure before removing or installing any vent valve. Install the valve at the highest point in the piping loop or at designated air-collection tapping points on the boiler or distribution header to ensure effective air removal. Follow applicable plumbing codes, including IPC guidelines, for threaded connections and pressure ratings.

WARNING: This product can expose you to chemicals including lead, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.