Caleffi 1/2″ Hygroscopic Automatic Air Vent for Radiators

CALEFFI 1/2" Automatic Hygroscopic Air Vent for Radiators

The CALEFFI 5080 Series hygroscopic air vent is suitable for both automatic and manual operation. 

In manual operation, the basic principle is to turn the valve from the closed to the open position and let the air out until water appears.
In automatic operation, the principle is to vent the air according to the change in volume of the cellulose fiber cartridge inside the valve.

Air can be vented manually by turning the valve back one turn from the fully closed position.
This is the most common method when filling the system.
For automatic air venting, the valve must be in the fully closed position.

When the hygroscopic discs are fully wetted, their volume increases by 50%.

Thus, under normal operating conditions, when the disc is in contact with water, the valve closes due to the increase in volume.
When air builds up in the system, the disc starts to dry out again; its volume shrinks and the opening needed for air venting is created.

CARTRIDGE REPLACEMENT

Unfiltered or hard water in the system may cause the disc to deform over time.
It is therefore recommended to replace the cartridge at least every 36 months.
The cartridge can easily be replaced without draining the radiator.