Vent fans that include a heater however should not be installed over a shower.
Best location for bathroom exhaust fan.
One installed in the shower stall and the other installed above the toilet.
In larger bathrooms two fans might be necessary.
Where to place your bath exhaust fan.
First the fan should be located in the area of the bathroom that is exposed to the most moisture.
Basically a bath exhaust fan is something that is used to help get all of the moist air out of your bathroom so that mold cannot.
This cross breeze will assist greatly in removing the steam vapor and odors from the room.
Once again the goal is to locate the fans so they are as close to the source of contamination moisture or odor as possible.
Plan your vent ductwork route.
The perfect place for an exhaust fan is near the moisture.
As long as the wiring for your bathroom vent fans is attached to a ground fault circuit interrupter gfci and the fan is rated for a shower area the best place to locate your vent fan is on the ceiling in or near the shower where it will do the most good.
Drill a locator hole.
Exhaust fans are no longer just for the bathroom.
The space above the bathtub or shower is damp and moist and therefore the best spot is near the shower area.
Secondly consider a location that allows for the shortest most direct route to the external vent if you are ducting the fan.
Tips for positioning a bathroom vent fan.
Ideally the exhaust fan would be positioned opposite this source of fresh air which promotes a cross flow of ventilation.