Do you want to learn how to fix a noisy bathroom exhaust fan?
Noisy bath fans can have numerous causes, but it can usually be boiled down to just a few things.
In this guide, I will go over...
- Cleaning the grille cover
- Oiling the fan motor
- Checking the vent duct
- How to buy a quiet new bath fan
Let's get started with this guide!
A loud and noisy bathroom fan is one of the most common complaints among new homeowners.
Especially with lower quality fans that are 'builder-grade', these are already pretty loud—but they get even louder as they age.
When bathroom fans get older, the motor itself can lose lubrication, the fan blades can become misaligned, the grille can get clogged with dust, the duct can impede air flow, and other problems that can make a bathroom fan loud.
Read Also: What Are The Best Bathroom Fan Switches?
1. Dirty Grille Cover
As a home inspector, one of the most common issues that I put in my reports is a clogged or dirty grille cover. Dirty bathroom fans can even become a potential fire hazard if a dirty fan motor overheats.
The bathroom fan grille is the usually the only 'visible' thing of the bathroom fan. Typically white or beige, these grilles can quickly become clogged with dirt and debris. Unfortunately, most homeowners never clean the bathroom fan grille (even though it's easy to do) and a dirty grille can make a fan very loud.
Since the bathroom fan isn't sucking in enough air, the bathroom fan can make weird noises due to a dirty grille. You can read my full guide on cleaning bathroom exhaust fans right here.
2. Dried Out Motor Bearings
Older bathroom fans sometimes have oil wick bearings that need to be periodically lubricated with light engine oil. Similar to cleaning the grille covers, oiling a fan motor is rarely done.
These bearings are what help the motor run smoothly, and if they aren't maintained with oil, the 'wicks' will become dry, and will cause the motor to run rough. A rough motor can make significantly more noise than a well-oiled motor.
I recently oiled an old Broan bathroom fan and it made a big difference in the sound quality, and it also made the fan run much more effectively.
To put oil into these wick bearings, the bathroom fan motor will need to be removed and then the bearing brackets will need to be uninstalled. Pretty much any light engine oil will suffice, and a few drops in each oil part may be all that's needed. My article on the six steps of oiling bathroom fans goes into the details, check it out.
3. Fan Blade Misalignment
And if you remove the fan motor to oil it, it's also a good time to make sure that the fan blades are spinning correctly.
If one of the fan blades is hitting something, or if it is 'wobbly' as it spins, then that can also add a lot of noise when running. Simply spin the fan blades with your finger, and see if you notice anything unusual about how it spins. If it isn't spinning smoothly and in a balanced fashion, you may need to replace the fan blades or just buy a new bathroom fan.
4. Too Many Duct Bends
Another problem that can add noise is too many duct bends. The more duct bends, the more air resistance there will be, which will create more noise. Ideally, a bathroom fan duct should have 3 or less bends, and preferably no sharp 90-degree turns. Preferably any duct bends should be smooth and gradual in order to maximize air flow (and reduce noise)
Also, if you can use rigid metal ducting rather then flex duct, this will also reduce noise. The 'ridges' in flex duct catches air, creates resistance, and can also add to the noise factor.
5. Clogged Duct
It is extremely common for birds to make nests in bathroom vent ducts as well as dryer vent ducts.
A bird's nest can completely stop air flow, and your bathroom fan won't work very well. The stopped (or nearly stopped) air flow can also add a lot of noise to a bathroom exhaust fan.
An easy way to check for air flow is to turn on the bathroom fan, and then check the outside for air flow. The bathroom fan vent cover should have a 'flapper' that will open with the fan is on. If the flapper isn't open (or moving), then there likely isn't air coming out.
You also may have a problem with a stuck flapper as well. If the bathroom fan vent is very high, you may need a ladder to properly inspect it for air flow.
6. Too Small of a Duct
With newer bathroom fans, many of them require larger than the standard 3-inch bathroom fan vent duct.
Many of the new (and quiet) bathroom fans require 4 to 6 inch duct widths for proper operation. If you use an undersized duct, the performance metrics of the bathroom fan will be off, and it may seem much louder than advertised.
Just Buy A New Bathroom Fan
Sometimes the easiest solution is to buy a new low-sone bathroom exhaust fan, especially if you can't find a simple reason for the fan loudness.
Bathroom fan sound is rated with 'sones' which is a measurement of noise perceived by human beings. If you double the number of sones, you will double the perceived loudness. In general, if you have a bathroom fan that is 3-4 sones or higher, that is considered relatively loud.
For quiet bathroom fans, I recommend buying a fan that is rated at 1-sone or less. You can read my product review on the quietest bathroom exhaust fans here.
Loud and rackety bathroom fans can be an annoying problem for homeowners, and there are usually a few easy solutions.
The first things I would do is clean the grill (if its dirty) and also oil the fan motor. If cleaning and oiling don't work, I would check the duct and make sure there is proper air flow. And if all else fails, you may just want to buy a new bathroom fan that is rated at 1.0 sone or less for a super quiet fan.