Exhaust fans are used to remove moisture and humidity from places in your home that need additional ventilation, like the bathroom, kitchen, or laundry room. The build-up of water vapor in these areas can trigger mildew and musty odors, and wreak havoc on walls and wallpaper. In many states, building codes require vent fans in all bathrooms that don’t have a window. But many homebuilders and other experts recommend exhaust fans in all bathrooms, even those with operable windows.
When installing an exhaust fan in a residential bathroom, it’s best to place it at the highest point in the ceiling and close to the shower, which is the primary source of moisture. For the fan to work as it should, its metal housing needs to be secured tightly to duct work and should be set up to blow outdoors and not into an attic or crawlspace. This would simply push the water vapor into those areas and potentially cause mold and mildew issues there instead.
Over time, exhaust fans can have diminished performance. If you suspect your bathroom fan isn’t removing moisture from the air like it should, consider these potential issues:
Make Sure It Is Actually Being Used
It goes without saying that a fan has to be turned on to be effective. However, in many households, the noise from exhaust fans has been known to deter its use. Here’s an easy fix: Consider connecting the bathroom light to the electrical for the fan so one can’t be used without the other. This might require a call to an electrician, but it solves the problem.
Check the Power
When your exhaust fan is being actively used but just doesn’t seem up to the task, check its power rating and make sure it matches recommendations for the size of the room. (See the diagram below.) The air movement of fans is rated by cubic feet per minute, or CFM. By measuring the square footage of your bathroom, you can determine the minimum ventilation (CFM) required. Note that higher ventilation rates are perfectly fine and can be more effective at removing moisture for only an incremental cost increase.
Keep It Clean
The performance of an exhaust fan suffers greatly if it’s not kept clean. Dirty components can trigger issues with the fan’s motor, which could mean the excess moisture you’re trying to remove from the bathroom won’t go anywhere even when the fan is on. It’s a good plan to clean the exhaust fan every six months.
With most models, follow these steps: Start by gently pulling down on the cover and squeezing the metal wires to remove the cover from the rest of the fan housing. Clean the cover with soapy water and then give it a good scrub with a clean rag to remove dust and dirt. Place it on a towel to dry while cleaning the dust off the fan itself.
As a safety precaution, turn off the power to the bathroom at the circuit breaker before cleaning the fan and its componentry. A long vacuum extension can be effective in sucking out dust and a gentle brush is best with the delicate interior motor parts. Use a damp microfiber cloth to wipe dust from the blades.
Choosing a Fan
Along with the power or CFM rating described above, there are a few other factors to consider when purchasing an exhaust fan.
All fans perform the same basic function (moving air from one room to the outside), but there are different models designed for certain applications. For example, lower-cost direct drive fans are better suited for the volumes of smaller rooms (2,000 CFM or less), while more powerful belt-driven fans are meant for industrial use and can remove moisture from rooms larger than 2,000 CFM.
Sound levels should also be researched prior to making a decision on an exhaust fan. Sones are the unit used for measuring sound pressure levels. For comparison, the sound of a quiet library or movie theater is typically between 2 and 6 sones, while a factory machine shop could range from 15 to 50 sones. Target a rating of 1 sone or less if you want to make sure the fan you’re purchasing is on the quieter end of the spectrum. The sone rating along with the CFM should be listed on the outside of the box.
If you decide it’s time to replace your old exhaust fan, follow these steps:
- Start by turning off the power at the breaker.
- Remove the fan cover as described above.
- Remove the motor from the housing and unplug it.
- Disconnect the wiring.
- Remove the housing at the mounting screws. Slide the mounting over to remove the electrical connections and take off the duct.
- Follow the instructions that came with your purchased fan. Measure the new housing to make sure it fits in place where the old housing was located. If necessary, cut out a wider hole in the ceiling drywall.
- Connect one end to a ceiling joist
- Install a duct connector to the existing ductwork using HVAC tape. (Call a professional if needed.)
- Remove the wiring cover on your new fan and connect with your house wires. Match up the colors of the wire.
- Push the wires back into the housing and secure the housing with the duct connector and attach with screws.
- Press in the springs to attach the fan cover in the appropriate slots.
- Turn the power back on at the breaker and flip the switch on your new fan to test it out.
Remember, if your fan has become more noisy over time and isn’t performing well, first try a deep clean. But if that doesn’t seem to help the cause, it’s probably time to invest in a new one. If the installation steps above are beyond your skill set, call an electrician or an experienced handyman to help you out.
Product Compliance and Suitability
The product statements contained in this guide are intended for general informational purposes only. Such product statements do not constitute a product recommendation or representation as to the appropriateness, accuracy, completeness, correctness or currentness of the information provided. Information provided in this guide does not replace the use by you of any manufacturer instructions, technical product manual, or other professional resource or adviser available to you. Always read, understand and follow all manufacturer instructions.