A restaurant kitchen with a chef cooking food and commercial exhaust hood system clearing out the smoke.

How Does a Commercial Kitchen Exhaust Hood Work

A Commercial kitchen exhaust hood works greatly. In Fact, You cannot run a successful kitchen if your kitchen environment is safe and provides the best facilities. 

The stoves and different cooking appliances emit gas, toxins, grease, and dust particles.

A commercial kitchen exhaust hood helps to cover all the hazardous aspects that may compromise the safety of your workers and kitchen. 

But, before you install a commercial kitchen exhaust, understand the working principles of the exhaust hood so you can make the best decision. 

Working Principles of a Commercial Kitchen Exhaust Hood Work

You might be wondering why bother yourself with the working of a kitchen appliance. I can go to the market and buy one. 

Let me tell you that is not the case. There are so many options available in the market that it will confuse a lot. 

A clean kitchen with stainless steel kitchen exhaust hood mounted to the wall above the stove.

Let’s start with the working principle of your commercial kitchen exhaust hood. It’s pretty easy and basic. The hot air from the kitchen stove or other cooking appliances rises above. 

Professionals install the exhaust fan on the hood, to pick up the hot air, grease it, and direct them out of the building. Also, the hood may or may not have fire suppression qualities, depending on your installed type. 

The expulsion of grease, dirt, and hot air makes sure that the air quality of your commercial kitchen does not get weighed down. 

It also reduces any chances of hazards to the maximum. 

Basics You Need to Know about a Commercial Kitchen Exhaust Hood Work

1- Cooking Factor

You need to consider what type of appliance you are using. Whether it is light, medium, or heavy-duty appliances. Do you need to know what the thermal plume is? 

The simple answer to that question is the substances that rise from a heating source. The plumes from grilling stations or flipping burgers will be much higher than in a healing oven or frying station.

Plumes coming out of the grilled burger patties and going into the kitchen exhaust hood.

Consider what the menu of your commercial kitchen will be. If it is simple baking and cooking, it does not need a high exhaust rate compared to a kitchen. 

2- CFM Is Important in a Commercial Kitchen Exhaust Hood Work

 It is Cubic Feet per Minute. It measures how strong the air movement needs to be in your kitchen. 

According to your needs, there are different standards, but it should be 100 CFM for every 12 inches of your stove as a thumb rule. 

3- Makeup Air Is a Part of a Commercial Kitchen Exhaust Hood Work

This is the air that comes in through the exhaust hood in exchange for the kitchen air. 

Components of a Commercial Kitchen Exhaust 

  • Exhaust hood
  • Ducts 
  • Exhaust fans 
  • Makeup air units 
  • Commercial hood filter 
  • Fire suppression unit 

Exhaust Hood for a Commercial Kitchen Exhaust Hood Work

A kitchen exhaust unit made of stainless steel to prevent from rusting frequently.

This is the most prominent part of the commercial exhaust system. They can be either wall-mounted or an island canopy that hangs directly over the stove in terms of style. 

Based on function, we can divide the kitchen hood into two types. 

1- Type I Hood of a Commercial Kitchen Exhaust Hood Work

experts install these hoods over cooking equipment that produces grease. 

These hoods come with a fire suspension unit because the grease is more prone to catch fire and needs something to suppress it.

Let me give the example of appliances producing high grease and oil dirt. When working with charcoal, BBQ, and stir-fried food, they produce many grease and fumes. 

Type I hoods will have filters to catch all greases and prevent them from entering the exhaust lines. 

2- Type II Hood of a Commercial Kitchen Exhaust Hood Work

These hoods also take the name of oven hoods. Their primary purpose of the use is to remove hot air and steam. 

experts install them over appliances that do not produce fumes and grease but rather just heat. 

These hoods have the ability to create a comfortable atmosphere for people working in the kitchen, as the added heat will make it impossible to work in the kitchen. 

As it is removing heat, it also works by removing any foul odors that can undermine air quality in your commercial kitchen. 

Exhaust Fans in a Commercial Kitchen Exhaust Hood Work

A stainless steel kitchen exhaust fan mounted in the wall.

In commercial systems, professionals install the exhaust systems externally. Usually, there are two types of exhaust fans in the market. 

1- Belt Driven Exhaust Fans for a Commercial Kitchen Exhaust Hood Work

A belt driven kitchen exhaust model for proficient air flow.

As the name suggests, the motor exists independent of the fan blades. The connection between the fan parts as well as the motor is one or two belts driving force. 


  • It is cheaper than other alternatives out there. 
  • You have more control over the fan blade’s speed.
  • Makes a lot less noise. 


  • The issue you may face here is that the belt produces friction that can lead to wear as well as tear of the parts of the fan. This wear and tear mean you have to do a more significant deal of maintenance. 
  • Also, this proves to be less energy efficient as a lot of energy is lost in the friction produced by the belt. 

2- Direct Drive Exhaust Fans for a Commercial Kitchen Exhaust Hood Work

Three direct driven kitchen exhaust fans mounted in the wall.

These fans have motors that are directly connected to the fan propellers.


  • Energy-efficient as the propeller is directly connected to the shaft of the motor.
  • As there is no energy loss, it requires much less maintenance, saving a lot of money.


  • These fans are pretty expensive. 
  • They may be producing a lot of noise. 

Making-up Air Units 

The exhaust fans are sucking up the air and vent them out of the building. Not replacing the air will be a problem in your kitchen. 

Stainless steel air units for providing clean and fresh air in the house.

Therefore, people install air units. They replace the bad air with new fresh tempered air according to the kitchen requirements to maintain the internal pressure of the kitchen. 

The best type for a commercial kitchen is an evaporation cooling unit.

How do these temper the air? 

  • The fresh air goes inside the ducts that then passes through the cooling pads continuously damped by a water pump. 
  • The air, after being cooled, is forced into the building, making the overall atmosphere of the kitchen pleasant. 

Exhaust Filters

Type I hoods have grease filters, and nowadays. People use baffle filters in most kitchen exhaust hoods. 

They also ease the cleaning process as all the grease collected is stored separately. 

They are the most efficient in trapping the grease by changing their direction as soon as the grease particles hit the filters. Most baffle filters are made up of stainless steel. 

Fire Suppression Unit

These are beneficial to reduce any chances of a fire in your cooking appliances. It is necessary for all type I hoods to come with a fire suppression unit for the safety of a commercial kitchen.

The basic working principle of this part is that specific chemicals start to release whenever there is an increased chance of the grease catching fire.

  • The extinguishing chemical is concealed in a stainless steel box.
  • There are detectors placed in the kitchen hood set at certain heat levels. As the stove’s heat rises above the set parameters, the chemical is released through the nozzles and pipes.
  • Now here, you need to keep in mind that the hood should cover all of the stoves to put out the fire completely. 

Ozone or Ultra-Violet Features

Some commercials exhaust the feature of ozone. The dust particles are large, and while passing through the ducts, they may accumulate, making ventilation difficult.

The ozone that releases into the ducts makes the grease particles smaller so as not to stick up in the ducts.

The benefit of ozone of ultraviolet features is reducing the maintenance as well as the cleaning of the ducts to quite an extent. 

  • It ensures a smooth flow of grease to the outside environment. 
  • It also helps in reducing unwanted odors in the kitchen. 

Maintenance of Your Kitchen Exhaust Hood

A worker maintaining the kitchen exhaust hood for better performance.

Maintenance is the key to working a commercial exhaust hood if you are not cleaning and maintaining the ducts, filters, and fans. 

Make sure it is clean according to its use. Commercial kitchens need their exhaust system cleaned once in three months to ensure a smooth-running exhaust system.

Negligence in the maintenance of your exhaust hood can lead to fire hazards that can put your workers and kitchen at risk. 

Know When to Clean Your Kitchen Hood

It is essential to know when it’s time to clean the kitchen exhaust hood before the situation gets even worse:

  • Unusual odors persist in your kitchen. 
  • Your fan motor is working so hard that it produces more sounds than usual. 

If you observe any atypical signs while working in your kitchen, never neglect them and ensure your exhaust hood is working efficiently. Also, ensure to clean the oily kitchen exhaust fan regularly.

Last Words

To summarize how your kitchen exhaust works: 

  • Grease particles enter the hood by sucking the exhaust fan.
  • The filters fit into the hood and capture the grease and dust particles.
  • The rest of the air flows into the ducts.
  • The Ozone system destroys any kind of large particles and odors.
  • Air is released into the outside environment. 

You need to know the working of your commercial kitchen exhaust in order to make the best decision in terms of the individual parts. 

Finally, if any issue occurs with the ventilation system, you would know the parts with their function, which will make it easy to know the root cause of system failure.