If you find the IPS02 is turning off too soon, you may need to increase it's time delay setting to further accommodate you. Since the IPS02 is a passive infrared (heat) sensor, it's triggered by the movement of heat sources. PIR sensors are not ideal when the source of movement is behind a partition (shower door), as they are better suited for line-of-sight movement. For a bathroom, I would recommend an ultrasonic sensor which sends out high-frequency (inaudible) sound signals and captures their reflections, triggered only when a change in response time is detected. These soundwaves can "see" around corners and partitions, are most commonly used in bathrooms/locker rooms/etc. For your usage, I would recommend a sensor like our OSSMT-MD.
I looked up one of those OSSMT-MD, I found them at HomeDepot. I also found 'ODS15-ID', would this work as well, or am I looking at this situation wrong?
The light/fan unit that the electrician installed has a sensor on it, so that the fan will operate at a high rpm when the bathroom is occupied. Then the fan goes back to a lower rpm when the bathroom is unoccupied. That unit was installed because my house has been tighten up to prevent any 'cold' air from getting in during the winter months and 'hot' air from getting in during the summer months.
So with that in mind, will either of the switches (OSSMT-MD or ODS15-ID) work?
The ODS10 is also a PIR sensor, like the IPS02, so it will still have trouble sensing movement behind partitions. The OSSMT has both PIR and ultrasonic sensors, which allows it to work in areas where there will be movement outside the sensor's line of sight. Both sensors are relay-based, and are designed for ON/OFF control, not speed control. I'm not sure if that becomes a problem with your fan setup though.