The extraction flowrate provided by these grilles varies with humidity. The flowrate is also automatically increased when the room is occupied.

It is ideal for extract from shower rooms and bathrooms where there is also a WC. It minimises the extract rate at low humidity levels. Conversely, it provides higher levels of extract when needed.

Extract rate varies from 1.4 - 12.5 L/s in proportion to the relative humidity range of 12%-52% RH. Extract rate is boosted to 8.33 L/s when occupancy is detected.

 
Note: A 9V alkaline battery (type 6LR61) is required to power the occupancy sensor. This has a life of about 2 years.