Glowworm Automatic Air Vent 0020014161
The automatic air vent is a pressure safety measure the central heating unit. They work by using a float to release built up air. As water flows through the heating/cooling system, a float within the automatic air vent opens or closes depending on the water level. If the system contains no air, the float will be pushed to the top and the vent will be closed until the water level drops.
This part is present in 12 different boilers in the Glowworm range