How to check bathroom exhaust fan. If this is the case simply reset it. The better the quality of the fan you select for your bathroom the quieter it will be. If the airflow of the fan is less than what is needed you might want to consider replacing the unit. Not audible to the human ear. Identify the exhaust fan circuit turn it OFF and Tag it with a Note before working with the wiring. Otherwise you might have to fill the entire bathroom with fog before its actually sucked into the exhaust fan. Have the proper size exhaust duct exiting the fan to the exterior.
First to determine if an exhaust fan is working turn on the fan and hold a container of baby powder about 6 inches from the intake grille. Turn the fan on and put the toilet paper up to the fan. If you are still unable to locate or identify a part necessary for testing described here make sure to check out the metallic plate on the fan motor. If the damper does not move freely or there is an obstruction in the ductwork your bath fan may not be able to do its job. And when the unit quits working or needs repair you REALLY begin to appreciate all it does on a daily basis. 15 minutes may be longer or shorter than required to keep your bathroom dry depending on the bathroom size building materials windows etc.
Turn the fan on and put the toilet paper up to the fan. But some older homes have no supply register in the bathroom so the undercut of the bathroom becomes the sole source of incoming air to replace the air that is exhausted by the fan. In our example you will need at least a 100 CFM exhaust fan. But your ventilation fan plays an important role in the proper air humidity and odor control of your bathroom. 15 minutes may be longer or shorter than required to keep your bathroom dry depending on the bathroom size building materials windows etc. Bathroom extractor fans are mandatory in any bathroom without a window and still highly recommended in bathroom with windows. The fan should suck the toilet paper up and it should stay attached to the fan. These are the equivalent noises for sone levels of exhaust fans.