The humidity sensor is not bring the fan on
It may be that the humidity level within the room is not high enough to trigger the fan. Where necessary, with most humidity fans you can adjust the sensitivity of the humidity sensor. See product fitting/wiring instructions for guidance.
Why won't my humidity fan stop running?
If you have a humidity controlled fan which is staying on most or all of the time, then there are a few points to consider before assuming the fan is faulty, as in most cases when we receive calls with suspected fault humidity fans, they are in fact operating exactly as they should be, and many are returned when there's nothing actually wrong with them.
Firstly, a newly installed humidity controlled fan will normally run for an average of half hour whilst the humidity sensor acclimatises, this is completely normal, so please leave the unit to allow it time to settle down.
Where necessary, with most humidity controlled fans, you can adjust the sensitivity of the humidity sensor. To make the fan less sensitive to humidity, you will need to adjust the sensor towards the maximum set point. Do not expect to see an instant reaction after adjusting the sensor, and please remember to leave the fan for at least half an hour to acclimatise. See the product fitting and wiring instructions for further guidance and before carrying out any maintenance or adjustments on your fan you should ensure that you have safely isolated it from the mains supply.
If your humidity controlled fan has a pull cord, it is also possible that somebody has pulled the cord to the override position, in which case the fan will run continuously until switched back to the sensor mode. Some but not all fans with a pull cord will have a neon light to indicate when the fan has been pulled to override.
Lastly, a humidity controlled fan is looking at the ambient humidity level to activate/deactivate the fan, and so it is important to remember that normal ambient humidity levels on a given day can trigger a humidity fan in just the same way as humidity generated by steam from the bath/shower room or Kitchen if the humidity level rises above the set-point. In addition, new build properties, as well as refurbished and redecorated properties will go through a drying out stage during which time the humidity level within the room will likely be high enough to trigger the fan.