Choosing the Right Bath Fan
Reading time: 3 minutes
Bath fans are an essential element to any bathroom - used properly, they help eliminate excess moisture to avoid mold buildup, odors, and foggy mirrors. And in most municipalities, they’re required by code.
Which option is best for your project? Consider these details and best practices.
Ceiling-mount bath fan or remote-mount bath fan?
Different situations calls for different types of fans, and we offer multiple kinds of bath fans. Use this section to decide whether a ceiling-mount bath fan or a remote-mount bath fan is better for your application. Then, use the following section to determine the amount of CFM required for your applicable situation.
Can Remote-Mount Bath Fans Be Used on the First Floor?
Because there are often finished levels above, first-floor bathrooms can be a challenge to ventilate with vertically-routed duct work. When duct work is routed horizontally between two levels of the home, it can be difficult to locate a remote-mounted fan indoors. However, the exterior exhaust fan offers a solution to this challenge with an exhaust fan that mounts on the exterior wall. The fan’s natural sound is kept outdoors, at a distance from the ceiling grille for quiet operation, and removes moist air from the space efficiently and quickly.
However, while this solution may work for some homes, others may utilize an exterior side wall vent. In this case, exhausting moist air under the roof line may not be the best course of action, as the bathroom air may partially drawn back up into the the roof line and cause an issue. For this issue, we recommend using a remote-mount bath fan connected with insulated duct to a gable end, through the roof, or however it makes the most sense to the installer to exhaust moist air out of the home.
Noise
Even though a traditional ceiling-mount bath fan may be remarkably quiet, its noise still might feel intrusive to some homeowners. Remote-mount bath fans eliminate the sound factor due to the placement of the fan at a greater distance from the bathroom. Also, ceiling grilles with or without lights can be easily positioned over showers, whirlpool tubs, steam showers, toilets, and/or vanities and connected to the remote-mount exhaust fan.
Remote-mount bath fans range from 100 to 370 cfm of air and can be specified with or without a light. Their seamless grille makes for better aesthetics.
Removing Moisture from Multiple Locations or Bathrooms with One Fan
Depending on Code and what the homeowner desires to see, homes with more than one bathroom may have one bath fan exhausting air from multiple bathrooms simultaneously.
The CVS remote-mount bath fans offer dual- or quad- port functionality to rid the space of humid air. Additionally, large bathrooms could use the extra ports to exhaust multiple areas of the room.
What Size Bath Fan Do You Need?
If the bathroom is 100 square feet or smaller, Home Ventilating Institute (HVI) guidelines require 1 CFM per square foot of bathroom or a minimum 50 CFM of fresh air flow. To find the square footage, simply multiply the length of the bath by the width. For proper airflow in typical installations (when duct losses aren’t calculated), use 0.1" water column for ceiling-mount fans, and 0.2" water column for correct fan selection.
If the bathroom is over 100 square feet, ventilation is calculated based on the fixtures in the bath. Allow 50 CFM for each standard toilet, shower, or tub. Whirlpool and jetted tubs are calculated at 100 CFM. Add up the CFMs for all fixtures and you will have calculated the total CFMs required.
Additional Bath Fan Considerations
A bath fan can only do its job if the homeowner uses it, and not everyone remembers. Specifying a bath fan with a humidity sensor, such as PRO Plus bath fan or a bath fan with our humidity sensor accessory, eliminates the human factor by automatically turning the fan on when there is a rapid to moderate increase in humidity or when humidity rises above a user-adjustable set point. The fan will shut off at a user-adjustable 5 to 60 minutes after humidity stabilizes and is below the set point. The PRO Plus series also includes a motion sensor. When motion is detected, the bath fan - already running continuously at the pre-set low speed—will increase to high speed. The fan will continue to run after the person exits the area for 20 more minutes.
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