The humidity sensor incorporated in the BXC air exhaust grille comprises an array of strips of polyamide; their natural hygroscopic properties are used to control one of the two dampers in the airflow. Aereco has been using this type of mechanical sensor since 1983, when it patented the principle.
Inherently reliable because of its simplicity (it operates without electricity), the array expands or contracts according to the relative humidity to which it is exposed. This movement is transmitted to the damper, thereby determining the flow area of the air exhaust grille. This very responsive sensor (it reacts in less than two minutes following a sudden change of humidity) not only detects humidity but also controls the dampers with no additional energy input, using the natural motive force of the fabric subjected to a variation of humidity.
Located outside of the airflow, the sensor is not at risk of clogging and retains its properties: its operation is guaranteed for 30 years. Each product undergoes no fewer than seven inspections and tests to make sure of its performance. A further advantage is the device’s operating mode: proportional to the level of humidity, unlike most electronic sensors (hygrostats) incorporated in the fans on the market, which control on/off switches rather than adapt to the ventilation needed.