A Glow-worm automatic air vent is a safety mechanism within the central heating unit. They work by using a floatation device to release accumulated air. An automatic air vent's float opens or closes based on the water level as water flows through the heating and cooling system. The vent will be closed until the water level drops if the system is full of water, at which point the float will be forced to the top. The Glow-worm Economy Sealed System Kit, Ultimate Sealed System Kit, Micron 30 FF, Mi

Brand Name	Glow-worm