There are a number of different choices when you want to replace or install a new bathroom fan. How easy the job will be depends on the availability of electric to the area and how you will vent the fan to the outside.
For single story homes or for bathrooms on the top level of the house installing a fan means you will need to get into the attic to install the vent pipe, run your electrical wires and attach the fan to the ceiling joists. If you are placing a fan on the first floor of a two story home you will need to find the floor joist locations of the floor above and remove enough drywall that you can get the vent to exit the sidewall of the house.
Remember whether you are venting through an attic or sidewall you will need to make sure that the moist air exits the home. Do not vent into an open attic. Moisture can cause rot and it can attract bugs that will nest near the heat in the winter. Un-vented bathroom fans in attics are one of the favorite spots for carpenter ants and termites to live.
So, what type of fan should you install and what special features can you get. Basic fans start under $30 and will provide good quality air cleaning their only drawback is noise. High end fans can cost well over $100 but offer better styling and may look more like a decorative light fixture then a fan. Units can include regular or even sun tanning lamps. The price and features you want are available depending on what you are willing to pay.
Bathroom fans are rated in sones or db and they rate the amount of noise the fan will make as it runs. The best way to tell what level of quietness you want is to go to a store and listen to a few of them. Remember that lose mounts of the fan box can increase the noise level. Also you should decide whether or not you want a silent fan not everyone does as the fan noise may afford you some privacy.
CFM Cubic Feet Per Minute
The fan you pick should be able to clean the room air by pulling fresh air from the rest of the house into the bathroom. The CFM size you need will depend on the size of your room and fans are rated anywhere from about 80 cfm to a few hundred cfm. A 100 square foot room 10×10 feet and 8 foot tall is about 800 cubic feet of air when not counting the tub and vanity. A 80CFM fan will take about 10 minutes to totally exchange the air in that size room
It may be easier for you to replace your ceiling light in your bathroom with a lighted bathroom fan this way you can save yourself on connecting another electrical wire and switch. Some of the decorative models out there are very difficult to distinguish from a regular decorative light fixture but the amount of light they give off may not be enough for use in-front of a mirror.
Installing a fan is pretty simple once you have installed the switched electrical wire to the area the fan will be mounted. You want to cut enough drywall away that the opening of the box will be exposed to the room below. To do this follow the manufacturers recomendations or make your own template.
Cut the opening with the hole saw and place the fan in place. If you are installing a fan in a first floor bathroom you may need to cut the opening larger then use a new piece of drywall with the smaller opening cut in it.
The wiring for the fan is done inside the box so you will need to partly disassemble the box and make the connection with wire nuts.
Use screws to attach the box to the joists to reduce the posibility that a nail can come lose from vibration.
Test the fan and mount the decorative cover on the inside of the bathroom.
Attach aluminum flexible duct to the exit flange of the fan and route it to the nearest wall or soffett using a duct work vent where it exits the home. It is important to take account for any rain that may enter the home through this vent so use a vent that has louvers that will open when the fan is activated and close from gravity.
The YouRepair Store has a full line of bathroom fans and electrical products and tools to help you get your next project done. Remember that orders over $25 usually can ship for free.