Honeywell Brass Auto Airvent HONEYWELL E121 Automatic Air Vent Valve is a reliable automatic venting device and is suitable for venting of air or gas from heating systems or heat process installations. E121-3/8A = Standard version, Connection size R 3/8″ E121-1/2A = Standard version , Connection size R 1/2″. . . #Honeywell Automatic Airvent Valve #Honeywell Auto Airvent Valve #Honeywell Auto Airvent Vadodara #Honeywell Valve Supplier in Vadodara