BAXI AUTO AIR VENT 720777601
The automatic air vent is a pressure safety device in the central heating unit. They work by using buoyancy to release accumulated 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 is full of water, the float will be pushed to the top and the vent will be closed until the water level drops.
This part is present in 10 different boilers in the Baxi range