How to Upgrade Your Bathroom Fan & CFM Calculator

The bathroom vent fan is an underrated and under appreciated component in your home. Although lovingly nicknamed the “fart fan”, it is for more than removing the aftermath of a gluttonous taco Tuesday. Bathroom fans remove moist air that cause mold, mildew, and rust in your bathroom. So, we’re going to teach you how to upgrade your bathroom fan.

Juan Jimenez
April 11th, 2022
home upgradesindoor air quality

Why Should You Upgrade Your Bathroom Fan

Obviously if you have an old fan that isn’t working, you’re going to need a new one. But if it’s working, do you need to upgrade it?

Unfortunately, builders often install the cheapest components and materials in our homes. So, there is a good chance that your existing fan doesn’t have a high enough CFM rating (cubic feet per minute). You can check out our CFM calculator below.

In addition, builder grade fans and older fans have a higher sone rating. This is the sound rating. You may not realize how much the loud fan bugs you until you’re yelling over the fan trying to talk to your partner. Although, some guests may appreciate a loud fan in the powder room. Everyone is always nervous about being heard.

Ultimately, if you have a larger bathroom, or hate your loud fan, its time to upgrade to a new bathroom fan. Fortunately, upgrading your bathroom fan is an easy DIY project even if you don’t have attic access.

Tools and Materials Needed

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It’s a pretty straight forward job and no special tools will be needed.

Ladder to reach the fan

Phillips and Flat head screwdrivers

Needle nose pliers

Utility Knife

Metal Tape

Reducer (if your new exhaust fan’s exhaust port is bigger than your current duct)

Optional But Highly Recommended

Power Drill

Oscillating Tool

Step 1. Bathroom Fan CFM Calculator

The most important step is upgrading to the proper size fan. Your old bathroom fan probably has a 50 cfm rating. That’s because 50 cfm is the minimum required by code. Likewise, that is what most builders install. It is important to realize that 50cm is only enough for a bathroom about 47 sqft with 8 foot ceilings. Use our bathroom fan cfm calculator below to determine what size you need.

Step 2. Pick the Sone Rating

Next, pick the noise level that works for you. In general, anything below 1 is considered quiet. More specifically, the quietest bathroom fans have a sone rating of .3. For ventilation fans in the master bathroom, you’ll probably want the quietest fan you can afford. However, your guests won’t mind some white noise in the guest bathroom.

Step 3. Remove and Replace Your Bathroom Fan

If you learn better with videos, we’ve got it all recorded for you. However, if you like reading instructions, we’ve got that too.

As with any electrical work, turn off the power. Go to your breaker box, and turn off the applicable breaker. Confirm its off with a wiggy, or by trying to turn on the fan.
Remove the vent cover. It usually pulls out and has spring retention clips.
Unplug the fan motor
Use some needle nose pliers to unclip the motor plate from the housing. They’re all a little different but usually apparent on how to remove them.
Remove the motor plate from the vent fan housing.
Use a flat head screwdriver or needle nose pliers to remove the wiring cover.
Untwist the wire nuts and separate the fan electrical wiring from the house wires.
Find the screws or nails securing the housing unit to the ceiling joist. Carefully remove them.
Partially remove the fan to get access to the duct work. Remove the duct and then fully remove the old bath fan.
READ THE STEP BY STEP INSTRUCTIONS for your new bath fan. They will all be slightly different.
If needed, enlarge the existing hole for the new bathroom fan.
Install any brackets called for in the instructions that you should absolutely read.
Connect the electrical wires. Generally, it is black to black, white to white, and green to the bare copper wire. But read the instructions for your specific model as they might use different colors. Make sure you use a cable connector, or cable clamp where the electrical cable goes through the metal box.
Connect the vent pipe with foil tape. DO NOT USE DUCT TAPE.
Insert the entire unit into the ceiling hole and attach PER MANUFACTURERS INSTRUCTIONS.
Plug in the fan and put the new fan cover on.
Turn on the power and test your new bathroom fan!

Important Considerations

No video or list of instructions can cover every nuance of each individual fan. Make sure you read the manufacturers instructions.

Now is a good time to replace the regular fan switch, for a timer switch. The whole purpose of the fan is to remove excess humidity from the bathroom. That being said, many people don’t leave their fans on long enough to do that. With that in mind, consider going with the timer switch to ensure you’re getting the most out of your bathroom fan.

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