Bathroom Exhaust Fan
An exhaust fan is desirable in any bathroom, and it is required in bathrooms that have no windows or windows that can't be opened. Bathroom fans should exchange the air in a bathroom completely every 5 minutes. In addition to keeping the air fresh, they also help inhibit the growth of mildew and other fungi that easily breed in a bathroom. If possible, listen to a fan of the model you are buying; some are pretty noisy.
Before beginning any electrical work, be sure you have the
required permits. Failure to do so is illegal and may invalidate
your homeowner's insurance. Many changes will be dictated by electrical
code (for example, the number of outlets per circuit or use of
special GFCI outlets in bathrooms or kitchens). Your service professional
should be familiar with these codes.
New or existing fan
Your service professional will need to know whether you're replacing an existing fan or installing a bath fan in a new location so he or she can more accurately gauge the cost, time and materials needed to finish the job. If ductwork needs to be run from the bathroom to the outdoors, it will take more time and possibly include work inside the walls, which could add to the cost of the project.
Fan features
Your service professional also needs to know what combinations of features -- fan and heater, fan and light or fan, heater and light -- you want on your unit. Something else to consider is a humidity sensor that turns the fan automatically if the bathroom air is too humid, or a timer that will turn the fan off after it has run for a while.
-- Tips courtesy of HomeAdvisor.com