Commercial Exhaust Hoods Guide


Commercial exhaust hoods play an important function within a commercial kitchen by allowing for ventilation of hot air, smoke and grease vapors away from and out of the kitchen, thereby improving the safety and performance of a ventilation system.

Since commercial kitchens generate high levels of heat and air contaminants, proper performance of the ventilation system is crucial to a commercial kitchen and its associated restaurant in order to operate properly and hygienically.

The types of equipment utilized within a commercial kitchen, along with equipment sizes and locations, will determine the types of commercial exhaust hoods to deploy within the kitchen to ensure for proper ventilation. This article will discuss the various types of commercial kitchen exhaust hoods, their designs, and proper placement within a commercial kitchen. 


Types of Commercial Exhaust Hoods

There are two primary types of commercial exhaust hoods - the Type 1 Canopy Hood that is designed for use with appliances that generate excessive quantities of grease and related vapors that necessitate a fire suppression system.

These are often referred to as "grease hoods" and are usually installed above grills, deep fryers and cooktops. A Type 2 exhaust hood removes heat, moisture, and odor from non-grease generating appliances and equipment. These are often referred to as "condensate hoods" and are frequently installed over dishwashers and other small, steam producing kitchen equipment such as steam tables, pasta cookers, rice cookers and toasters


Commercial Exhaust Hood Designs

The most common designs for commercial exhaust hoods include wall canopy hoods, island canopy hoods,and low proximity hoods. Wall canopy hoods are mounted to a wall located behind cooking equipment, extending over appliances to capture heat and grease laden vapors.
Island canopy hoods are installed to the ceiling and hang above equipment islands that are positioned away from walls. Island canopy hoods require stronger exhaust fans because all four sides of the hood are open. Low proximity hoods are mounted close to appliances, positioned near low ceilings and generally smaller in size. Also known as backshelf hoods, these commercial exhaust hoods are designed for use with counter-height cooking equipment. 


Kitchen Equipment and Exhaust Fans

Both the proper size of a commercial hood and the strength of its exhaust fan are important considerations that will depend upon the maximum cooking surface temperature of the appliances located beneath the hood. The maximum cooking surface temperature is directly dependent upon the amount of heat, smoke and grease that the cooking appliances are generating.

The level of exhaust volume that a hood is required to move is measured in airflow efficiency at the rate of cubic feet per minute (CFM). Low-exhaust equipment such as ovens, steamers and small kettles require exhaust rates of 150 to 300 CFM.

Medium-exhaust equipment such as fryers, griddles, ranges and larger kettles require exhaust rates of 150 to 400 CFM. High-exhaust equipment such as woks, along with charcoal and woodburning charbroilers, require exhaust rates of 200 to 600 CFM.


Equipment Dimensions and Hood Placement

It is important to make certain that your commercial exhaust hood is the proper size to manage the amount of exhaust that will be produced by the underlying cooking equipment. Hoods that are too small will prove insufficient to handle the volume of exhaust produced, while overly large hoods can result in unnecessary extra energy costs. Height placement also matters.

Measure the size and height of your underlying cooking equipment and position the exhaust hood from six to twelve inches above the cookline to increase the volume of heat and grease absorption from the appliances and surrounding areas. Furthermore, the hood should be mounted in a manner that its bottom edge is positioned between 78 and 80 inches above the floor. As a final note, appliances positioned beneath ceilings fewer than 8 1/2 feet high will require a low-proximity backshelf hood.



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