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Commercial Kitchen Exhaust Fans

commercial kitchen exhaust fan collage

Professional Grade Commercial Kitchen Exhaust Fans Provide Years of Reliable Performance

Exhaust fans and blowers are a key component in a commercial kitchen design and makeup air applications. Commercial kitchen fans are typically used in restaurants, office buildings, shopping centers, convention centers, hotels and casinos. 

Let BPA Air Quality Solution's 100+ years of combined air purification experience match you up with the perfect restaurant kitchen exhaust fan or blower.

 

General Info on Commercial Kitchen Exhaust Fans & Blowers

Commercial kitchen exhaust fans are a vital part of your ventilation system. They remove odors and improve indoor air quality. Commercial kitchen fans also remove moisture, which can increase the level of humidity. High humidity can cause mold, mildew and bacteria growth which can ultimately result in major health code violations.

Common Exhaust Fan Systems

The two most common types of fans are impeller fans and blower fans.

  • Impeller fans move air with blades similar to airplane propellers.

  • Blower fans look like hamster wheels - they are often called squirrel cage fans - and generally are more efficient than impeller fans.

Most commercial kitchen exhaust systems have an exhaust fan, ducting and a hood. Some buildings have a central exhaust system, which is one or more fans, drawing air from the entire building (or parts of it) using a network of ducts.

A Heat Recovery Ventilator (HRV) also exhausts moisture and odors. An HRV is a self-contained ventilation system that provides balanced air intake and exhaust. Like a central exhaust fan, it can be connected to several rooms by ducting.

How good is your commercial kitchen exhaust fan: Is your fan...

  • too noisy?

  • not powerful enough?

  • not energy efficient?

  • a fire hazard?

How Do I Choose the Best Restaurant Kitchen Exhaust Fan System?

  1. Choose the quietest, most energy-efficient exhaust fan or blower in the size range required. Most exhaust fan and blower labels have ratings so you can compare noise and energy efficiency. Look for a fan with replaceable parts and permanent lubrication. A fan suitable for continuous use is preferable. Be prepared to pay more for a quality fan.

  2. Select low-resistance (smooth) exhaust ducting. Seal the joints and insulate sections that run through unheated spaces.

  3. Place the exhaust hood where it will not cause moisture damage on exterior surfaces.

  4. If you have heating appliances with chimneys, make sure that fans won't cause the appliances to backdraft.

  5. Install the proper controls.

Things to Consider when Choosing a Commercial Kitchen Exhaust Fan or Blower:

Noise
Look for fans labeled 'low noise' or 'quiet,' and check for the HVI or db (decibel) rating. If it is not rated, there is a good chance that it will be noisy. Noisy fans are usually of lower quality, use more electricity and deteriorate until they cease to function. Older noisy fans can also be a fire hazard. Anti-vibration pads or foam tape can insulate the fan housing from wood joists and drywall.

Fan Power Requirements and Airflows
There is more to energy efficiency than selecting an energy-efficient fan. Ducting can affect fan performance. Un-insulated, undersized, or droopy flex ducting, ineffective or dirty backdraft dampers and exhaust louvers can cut rated airflow by more than 50 percent!

Cleaning
Fans create static electricity which attracts dirt like a magnet to the fan and housing. The dirt can encourage mold growth and restrict air movement. Clean fans, housings, back draft dampers and exterior flaps seasonally.
 

Weather Hoods, Grills And Backdraft Dampers
Even when fans are off, stack effects and wind loads may cause outside air to enter or inside air to exhaust through fan ducting. Check the flaps from time to time to make sure they are clean and working. The exterior exhaust flap or louvers should be clean and in good repair to maintain unobstructed airflow and reduce air infiltration. Most exhaust ducts are fitted with a single flap exhaust hood or triple louver aluminum or plastic exhaust grill. Use weather hoods that lie flat on the wall in driveways and other places where hood-type units could be damaged.  Clean exhaust hoods of lint and nesting materials seasonally to ensure that the flap or louvers are not blocked or stuck open.

High Capacity Systems
High capacity, industrial or oversized exhaust fans, and range-top barbecue fans can cause chimney backdraft. Backdrafting occurs when air is drawn down chimneys, bringing dangerous combustion exhaust gases into the house. Avoid this by selecting sealed combustion heating appliances. If you have appliances with chimneys in your house, and you wish to install high capacity exhaust fans, you will need a matching supply air fan to balance house pressures.

Many ventilation contractors or salespeople are unaware of the effects of large exhaust fans on other house appliances. Make sure that your system is properly installed with supply air and that you have smoke alarms and carbon monoxide detectors to warn you if you have severe chimney back drafting.
 

Powerful Exhaust Fans Need Make Up Air


Ventilation Versus Evacuation
Vented kitchen fans help to maintain good indoor air quality. They remove combustion pollutants, moisture, cooking odors, and grease from the restaurant or house. Commercial kitchen range hoods must deal effectively with grease, in particular. One reason that commercial kitchen fans are so powerful is that they must maintain a high enough velocity to draw all contaminants into the hood. If this is not accomplished, grease gets deposited throughout the kitchen, creating a risk of fire. There are various rules of thumb for matching the size of the cooktop to the size of the fan. A common one is 300 CFM per linear ft of cooktop. Thus a 48-inch cooktop needs a 1,200 CFM fan. This standard comes from the commercial sector where codes are very specific about the installation of kitchen fans.

This is in sharp contrast to how kitchen fans are installed in a residence. There is no language in the residential codes that ensure the safe installation of large commercial fans. The residential kitchen ventilation requirement in all three Model Codes and ASHRAE Standard 62 is for a 100 CFM fan or range hood. The industry recommendation from the HVI is for a minimum of 40 CFM per linear ft of cooktop. According to this rule, a 48-inch cooktop needs only a 160 CFM fan.


Please see an online article from Home Energy for some insight into using oversized commercial kitchen fans in a residence.

Makeup Air
To operate any fan safely, the air that is exhausted from the inside to the outside must be replaced. This is why the Uniform Mechanical Code (UMC) requires makeup air for commercial kitchens. Makeup air is air that is intentionally pushed or pulled into the building in an amount more or less equal to the amount of air that is exhausted by the kitchen fan. Makeup air prevents fuel spillage and backdrafting from vented combustion appliances, such as gas water heaters or fireplaces, within the restaurant. Another purpose of requiring makeup air is to ensure that the fan can actually exhaust at its rated capacity. If the fan isn't running at its rated capacity, it does not maintain sufficient air velocity to trap the various emissions from the cooking surface. A building's tightness and exhaust duct configuration will affect the amount of air that fans inside it can exhaust. The tighter the building, the greater the pressure the fan has to operate against and the less air the fan can move. The amount of air that a fan can move against any given pressure is called its fan curve. Get too low on this fan curve, and a 1,200 CFM fan might exhaust only 1,000 CFM.


Makeup air is usually tempered (heated or cooled to offset the outside temperature) to ensure the comfort of kitchen staff. Installing makeup air devices also ensures that large amounts of air from the eating area of the restaurant are not drawn into the kitchen. This can create drafts that affect the comfort of the diners.

In many jurisdictions, the owner of a commercial building must pass a performance-based test that certifies that the makeup air is sufficient for the fan and grease filter to work safely. Testing and balancing companies typically administer these tests. They measure the flow of both the exhaust and supply fans and check to make sure the restaurant is not depressurized.

 

Performance

The right path is performance. This means that a test is used to determine whether a given installed system works as specified. Plumbers must pressurize the plumbing system, and it must hold that pressure for a given amount of time before an inspector approves it. Determining the leakiness of a plumbing system using a prescriptive approach would result in leaky piping and high utility bills.

An example of a code that is taking the path of performance is the Canadian General Standards Board 51.71-95. This code sets limits for depressurization caused by any source for a variety of combustion appliances. The limits are 5-20 Pa for various types of combustion appliance, such as fireplaces and condensing furnaces. This code requires testing. Nothing is assumed about the leakiness of the house; nothing is assumed about how much air a fan is exhausting. The worst-case depressurization test tells the inspector whether the system passes or fails. The 1999 Minnesota Energy Code uses a similar performance table with limits of 2-25 Pa for different appliances. It also allows the use of a prescriptive table or performance testing. The code requires a supply fan for kitchen exhaust flows over 250 CFM where direct vent appliances are used and a supply fan for all kitchen exhaust for other appliances. Flows must be matched within 10%.

Do It Right
Kitchen fans are important to maintaining good indoor air quality. At least one manufacturer says that its larger fan promotes a healthy house by "helping the house breathe." Unfortunately, if what the residents are breathing is combustion by-products drawn into the house by a kitchen fan, then these powerful fans only serve to undermine the indoor environment and endanger their health.

If large kitchen fans are installed at all, they must be installed as a part of a kitchen ventilation system that includes makeup air, and these systems must be performance-tested in the field.
 

Steps to take into consideration when designing a makeup air system:

Step 1:  Many companies install multiple fans and multi-speed fans in the same hood so that they can be switched on incrementally.  While more power is important, what is probably driving the market is the aesthetic appeal of architecturally designed range hoods. Hoods are often the focal point of the modern open commercial kitchen.

Step 2:  Decide where to introduce the makeup air. The logical choice is to bring air into the restaurant kitchen somewhere.


Step 3:  Determine how much makeup air is needed. If sufficient makeup air is provided, no depressurization will occur. Obviously, some makeup air will be provided through leakage. However, it is best not to count on that. Size the makeup air to match the fan.

Step 4:  Decide whether or not to temper. Except in very mild climates, it will probably be necessary to temper the incoming air during cold weather. This is most easily done by using inline duct heaters, also known as resistance heat, that kick in when the incoming air is below a set temperature.

Step 5:  Develop a control strategy. The makeup air system must work whenever the kitchen exhaust is running. When the fan is turned on, a motorized damper opens and the supply fan turns on.  The supply fan moves more air when the kitchen fan is turned to a higher setting. If the temperature of the air is below preset limits (50 of supply air), the inline heater comes on.

Step 6:  Test the system. Worst-case depressurization testing is critical. It is impossible to know the tightness of the building and the interactions between the makeup air system and other mechanical systems without testing. The worst case depressurization test tells you if the makeup air matches the exhaust air, and if other combustion appliances will backdraft.
 


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All Kitchen Exhaust Hoods

BPA Air Quality Solutions is the leader in providing you with the best choice of kitchen exhaust hoods or a complete cooking ventilation system that will solve your problems caused by smoke, grease and odors generated by either your home or restaurant cooking.

Our kitchen exhaust hoods emissions elimination systems installed in your restaurant or home...

1. Eliminates cooking odors
There are different odor control technologies used in the various kitchen exhaust hood systems. Let BPA Air quality Solution's 100+ years of combined air purification experience match you up with the perfect kitchen emission system for your specific needs.

2. Saves you money
Without an effective kitchen exhaust hood cleaning system, cooking grease and smoke causes grit and grime build-up on almost every structure these emissions come into contact with. This can cost you a lot of money in cleaning, maintenance and damage.

3. Keeps you in compliance (for restaurant and commercial applications)
A restaurant and commercial kitchen exhaust hood cleaning system will keep you within compliance with even the most strict federal, state or local environmental standards. Installing the correct commercial kitchen emission system for your needs the first time around eliminates the need for costly retrofits later on down the road.

 


Commercial Kitchen Exhaust Hoods

Commercial Kitchen Exhaust Fans

Kitchen Emissions Cleaning Systems

See our entire line of commercial kitchen emissions systems.

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BPA is for educational and research intentions only. Not intended as an alternative for medical treatment or advice.