How Do Kitchen Exhaust Fans Work?

Posted on May 1, 2020

We have to vent about something… It’s your kitchen. Specifically… Your kitchen exhaust fan. Many don’t know how they work. 

Your kitchen exhaust fan is critical to the health and safety of your kitchen. It can quickly improve the indoor air quality of your home, which can ward off a variety of health issues. 

So… What is a kitchen exhaust system and how does it work? Keep reading to learn more!

What Is A Kitchen Exhaust?

Your kitchen exhaust is a fan above the stovetop that removes the airborne cooking byproducts from the air in your kitchen. These byproducts can include grease, rogue spices, fumes, smoke, steam, and heat. While critical to your home kitchen, commercial kitchen exhaust fans are a necessary safety measure – as they often include fire suppression device to vent and extinguish fires.

How Do Kitchen Fans Work?

There are two types of kitchen exhaust systems, ductless and ducted. Ducted hoods are the most common. True to their name, they have a duct that the air gets sent through. These are popular in both homes and commercial kitchens. Ductless hood suck in the air, filter it, and send it back into the room. Let’s explore both of them below:


There are a few essential components to a ducted kitchen exhaust system. These include:

  • Hood: The hood is the most recognizable part of the system. This floats above the stovetop and houses the fan and filter.
  • Fan: Located inside the hood, the fan sucks the air through the filter and into the system
  • Honeycomb filter: Located inside the hood, filters grease particles and other byproducts
  • Ducts: Ducts are like a tunnel for the air to transfer outside the building. 
  • Ozone generator: Located inside of the ducts, the ozone generator cleans the air before it leaves the duct.
  • Lights: You can usually find these under or next to the hood to make seeing your culinary creations even easier

So let’s say that you start cooking dinner and after a while, your kitchen is warm, steamy, and smells delicious. Little do you realize, there are also hot grease particles in the air, and like heat, rises a little bit.

You turn on the fan. The steam and grease particles get sucked up into the bottom part of the hood. Within that hood, there are honeycomb filters that trap the large grease particles.  The rest of the air flows into the exhaust duct. In some commercial kitchens, an ozone generator cleans the air and an aero vent fan pulls the freshly cleaned air the rest of the way through the duct and out onto the street or rooftop. 


A ductless kitchen exhaust system works differently than a ducted system, but they do have some similarities. Ductless systems will recirculate the air back into the kitchen instead of the outside, which is why they’re sometimes referred to as recirculating range hood. In a ductless system, a powerful motorized fan sits above the stovetop. When the switch is flipped, the fan sucks the air up through a vent and filter.

In a ducted system, a standard honeycomb grease filter will suffice. In a ductless system, the filter is usually made out of charcoal and paper. This is because a ductless system sends the air back into the kitchen and must filter the air more quickly in less space than a ducted system.  Some manufacturers have made dishwasher safe filters that can be easily washed in your dishwasher. 

Next, the air is pulled through another filter into a blower. Generally, this will be a round filter made out of charcoal. Finally, the air exits the blower and recirculates through a vent back into the kitchen.


Maintenance of both ductless and ducted exhaust systems is important to ensure the longevity of your exhaust system and the safety of your home. Built-up grease can even cause a fire in your exhaust system. In addition to cleaning and changing your filters, you should have a professional regularly inspect your ducts and conduct preventative maintenance. If you own a home, check out our guide for cleaning your kitchen exhaust and if you own a restaurant, you can read more about how to clean your kitchen hood in our previous blog post.

Airpro Indoor Air

When it comes to kitchens, the delicious food you create isn’t the only thing you should be concerned about. Make sure you have your system inspected and cleaned before the surfaces of the system are heavily contaminated with grease. A little bit of preventative maintenance can go a long way in keeping a kitchen running smoothly and saving you money. 

In addition to regular maintenance, the team at AIRPRO can also help with fan hinge retrofitting and installations of access panels. Learn more about how we can help with your indoor kitchen exhaust!

Kitchen Exhaust Maintenance in Hawaii

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