the A-420A serves as the high or low-side reference point

Durable Sleeve Bearings: Engineered for quiet operation and long-term reliability in high-temperature environments

reducing time spent on modifications

featuring a 1/2-inch inlet and a 5/8-inch outlet for seamless integration

such as pump starts or boiler firing

Resideo FV180A Air Vent 320074-702 the A-420A serves as theThe Resideo FV180A Goldtop Universal Air Vent is a heavy duty solution designed to automate air purging in hydronic heating systems and cooling loops. Featuring a 1 4" NPT male connection, this brass automatic air vent is engineered for versatile implementation across systems ranging from 1 to a 150 psi maximum operating pressure. Its patented fulcrum design provides a venting rate up to four times higher than standard vents, effectively preventing