Restaurant Vent Hood - Commercial Kitchen Ventilation Education

KITCHEN VENTILATION 102

Ventilation is the single most important factor in the design, construction, and operation of a commercial kitchen.

An exhaust hood is an air intake device connected to a fan that removes smoke, cooking vapors, grease, steam, heat, and odors that are made by cooking and ware washing equipment.

There are several different types of vent hood systems on the market, the most popular being the Type I Canopy hood. A canopy hood is basically a hood that is hung from the ceiling and covers all of the cooking equipment under it. None of the equipment can extend outside of the hood and there should be a minimum of 6" clearances to spare on each end of the hood. Canopy hoods used for cooking equipment will also have a "compensating hood", or fresh-air make-up hood around the perimeter of the canopy hood to bring fresh outside air back in to replace the exhaust air going out. Therefore, there are two integrated components to a kitchen ventilator hood - exhaust air and make-up air.

A kitchen ventilation system also works interdependently with the buildings HVAC system to produce a properly balanced flow of air to the building. A very slight negative air pressure is preferred in a commercial kitchen in order to keep the heat and odors of a kitchen from migrating back into the dining area or other parts of the building.

There are many factors involved in determining the size and type of kitchen vent hood required . A lot depends on the type and amount of cooking equipment that will be going under the hood. #1 the equipment must physically fit under the hood and have at least 6" overhang left on each end, not extend out in front of the hood, and be matched to the proper size fans (air flow requirements) for the particular equipment.

There are four classes of cooking appliances that require different cfm or air flow requirements. These are referred to as light duty, medium duty, heavy duty, and extra heavy duty. By this we mean the heavier duty equipment expends more heat, smoke and grease and hence requires a higher volume of air flow to remove more smoke and heat. Just a few examples are as follows:

• light duty - ovens, kettles, and other non-grease producing appliances
• medium duty - fryers, grills, griddles
• heavy duty - electric broilers and char broilers
• extra heave duty - gas char broilers, woks, mesquite burning broilers

Ducting is another major component to a ventilation hood. The ducting must be installed in compliance with local and national building and fire codes. Ducting should have the shortest and most direct path to exiting the building. It is also important that all duct sizing be properly calculated according to the amount of air flow and velocities required for proper performance of the hood while keeping the balance of air in the building at a proper level as talked about previously. Exhaust fan ducts must be welded water tight and wrapped with approved fire wrap insulation. Bends and elbows in the ducting should be kept to a minimum so as to allow for better air movement. Horizontal runs should have a slight slope downward (approximately 1/4" per foot) back toward the hood so that grease and water vapor can run back to the grease catcher or water drain.

A certified fire control system will also need to be installed in all commercial kitchen ventilation hoods that have cooking equipment under them.

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Contact Jean's Restaurant Supply if you have any questions about commercial kitchen vent hoods. 1-866-618-4999