Automatic radiator air vent valve is designed to remove any
air trapped inside the heat emitters both during the filling
of the system and in normal operation. The automatic air
discharge happens when the hygroscopic cellulose fibre
discs are dry. As air is vented and water contacts the
hygroscopic discs, they increase their volume by 50%
which cause the discharge vent to close.
Float type automatic air vent designed to vent air that is released from
the water while being heated.