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Why Is My Bathroom Exhaust Fan Blowing Air Down?

Are you noticing air coming down from your bathroom exhaust fan? 

Although you don’t need to be alarmed just yet, there is something wrong with your bathroom fan when it starts blowing air in.

Fortunately, there are ways you can correct the problem and have your bathroom fan working correctly again.

Find out common reasons why your bathroom fan is blowing air down and how to solve it.

bathroom exhaust fan

What Does a Bathroom Fan Really Do?

Having a well-maintained and perfect-functioning exhaust fan does a lot of things for your bathroom. It’s an essential accessory that keeps your bathroom hygienically sound and healthy for everyone. 

Bathroom fans are especially important for limited spaces with no large windows to provide proper ventilation. They help get rid of the steam and moisture that can cause mildew growth spores in your bathroom.

So, how do bathroom fans actually work? 

In most cases, your exhaust fan will be fitted on the bathroom ceiling. It will then draw moisture, odor, and other elements up and out of your bathroom through the vent pipe. In short, bathroom fans work by sucking in air from the inside then blowing it outside. 

So, when your bathroom fan does the opposite, when it starts blowing in the air instead of sucking it out, there’s something wrong. 

Reasons Why Your Bathroom Fan Is Blowing Air Down

One of the common concerns with bathroom fans is when it blows air down instead of sucking it then sending it out. When this happens, there can be a few reasons why.

1. Stuck backdraft flapper

The backdraft flapper is an essential part of the overall function of your bathroom exhaust fan. It facilitates the airflow from inside the bathroom to the vent. The backdraft flapper is fixed to the exhaust fan to allow air to flow out of the bathroom when it’s open but prevent air from sweeping back in when it’s shut.

So, when your fan’s flapper is stuck open, it leaves room for the air from the outside to enter the bathroom. 

Meanwhile, if the flapper is stuck closed, the fan may still suck in air but will blow it right back inside the bathroom if the air can’t pass through the closed flapper. 

2. Reversed fan blades

Your bathroom fan has three major parts, the cover or housing, motor, and the fan blades. The rotational direction of the fan’s blades has a huge impact on how your exhaust fan functions. 

Ideally, you want the blades to turn clockwise so the air will get drawn upwards. In most bathroom fans, blades can only turn in one direction and manufacturers make it that you cannot reverse how a blade gets installed. However, some fans do have alternating motors, which means you can switch the direction of the blade’s rotation. If the blade is turned so it rotates counterclockwise, that might be the reason why our fan is blowing air down. 

3. Lint buildup in the fan

Although exhaust fans are essential for bathrooms, they rarely get the attention and care they deserve. They require regular cleaning and maintenance, and if not, dirt can build up in the fan with all the moisture and air it draws out. Lint buildup in the fan can restrict airflow, and that might be the reason why your bathroom fan is blowing air down.

4. Dirt and debris blockage in the vent pipes

Besides blockage inside the exhaust fan, dirt and debris can also accumulate in the vent pipe. When that happens, you will also have failed airflow. Although your bathroom fan may be working properly in drawing air in, blockage in the vent pipes would prevent air from going out completely. Hence, it will be pushed back into your bathroom. 

5. Damaged vent pipes

Besides dirt and debris accumulating in the vent pipes, another reason why your bathroom fan is blowing air down is a blockage due to a damaged or bent vent pipe. If air can’t pass through the pipe properly, then you’ll experience a backward flow of air. 

Is Your Bathroom Fan Blowing Air Down? Here’s How to Fix It!

Once you find out the reason why your bathroom fan is blowing air down, you can find ways to correct the problem. There are a few things you can do to make sure your bathroom fan works correctly and efficiently. 

  • Check the backdraft flapper.

Find out if the backdraft flapper is causing your bathroom fan to blow air down. Make sure it’s not stuck and no dirt and debris buildup prevents it from closing or opening properly. 

Tip: if the flapper needs changing, opt for a butterfly backdraft damper. It has a spring-loaded design that will only open once you turn on the bathroom fan, allowing minimal leakage. 

  • Check the fan blades.

Is the fan’s blade installed correctly? It should be rotating clockwise to draw the air from the bathroom out instead of blowing them in.

Another thing to check is if the fan blades have gotten loose. Over time, like any mechanism used at home, your bathroom exhaust fan can get damaged. Realign, secure, or replace it as necessary. 

  • Regularly clean your bathroom fan and vent. 

Cleaning your bathroom fan is necessary to prevent dust and dirt buildup that can restrict airflow. It’s recommended to clean your bathroom fan, including the grill cover, fan blades, motor, and flapper, once or twice a year. 

Tip: make sure you turn off the fan before attempting to clean it. You can use soap and water to remove any dust and debris buildup. If you can’t remove the fan and motor for a thorough cleaning, you can use a vacuum.

  • Change damaged pipes.

Ductwork connections can come loose over time, so check for connections, including possible holes and bents. 

Depending on your bathroom exhaust fan’s ductwork, fixing any damage can be a huge project, especially if the duct is too long with crazy turns. Older duct systems might need updates or a full replacement. 

Final Thoughts

Having proper ventilation is essential to keep your bathroom free from mold and mildew. It’s recommended to clean your bathroom fan and check for damages at least once a year to ensure it’s working properly. If there is any slight blockage in the fan and vent pipe due to dust and dirt buildup, your bathroom fan might start blowing air in instead of out.

Adam McCoy

Adam is an HVAC expert and the owner of Mackydo's HVAC Services with decades of experience in fixing and installing air conditioning units, furnaces, and every type of cooling and heating equipment you can think of.

Adam believes that your home is your sanctuary. He loves sharing advice based on his lifelong experience and treats every HVAC problem as if it was his own.

James B. Parker

At a young age, James' father taught him carpentry, and he was pretty much destined for a career in the construction industry. He worked as a professional remodeling contractor for some of the most prominent construction companies for several years, before deciding to pursue his passion for writing.

A vast amount of construction experience allows James to provide practical advice for those considering a bathroom remodel.

About Loo Academy

At Loo Academy, our mission is to offer trusted advice for everything related to bathrooms (design ideas, plumbing advice, showering & bathing tips, remodeling guides, and more) — a place where we all spend a great deal of time.

We work closely with qualified experts and follow a thorough editing and fact-checking process before publishing content.

Published content is regularly fact-checked and revised so that the information we provide is accurate and up-to-date.

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