The Altecnic hygroscopic automatic air vent can manually or automatically remove any air trapped within a radiator or a heat emitted both during filling of the system and in normal operation. In this way, when the system is operating under normal conditions, the discs are immersed and due to their increase in volume, close the valve. However, when air is present the discs dry out and allow the air to vent. Hydroscopic discs close very quickly, in just a few seconds, significantly decreasing the risk of leakage.