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Ventilation Rules of Thumb

Commercial Kitchen

Commercial Kitchen

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The illustration above shows a typical commercial kitchen application utilizing a roof mount upblast exhaust fan OR wall-mount upblast exhaust fan in conjunction with a supply fan. Note that not both exhaust fans are required for hood exhaust. Read on to determine how to size your exhaust and supply fans.

For commercial kitchen applications, when not specified by code, the following guidelines may be used to determine the minimum kitchen hood exhaust CFM:

Type of Cooking Equipment CFM/Ft.2 of Hood
Light Duty Oven, Range, Kettle 50
Medium Duty Fryer, Griddle 75
Heavy Duty Charbroiler, Electric Broiler 100
Static pressure usually ranges from .625" to 1.0" for 1 story buildings.
*NOTE - some local codes require 100 CFM/Ft.2 of hood area for wall style hoods.

Supply air is recommended to be 90% of your determined exhaust CFM. The remaining 10% will be drawn from adjacent areas to the kitchen, which helps prevent undesirable odors from drifting into areas such as the dining room.

For safety reasons, the NFPA (National Fire Protection Agency) has additional installation requirement for commercial kitchen applications.

  1. Use of Ventilated Roof Curb
  2. Use of Grease Collector
  3. Use of Clean-out Port
  4. Use of Hinge Kit
  5. Roof deck to top of exhaust fan windband - 40" min.
  6. Roof deck to top of curb - 18" min.
  7. Supply fan intake - 10' min. from all exhaust fans.

NFPA Considerations

* For applications where the 10' horizontal distance cannot be met, separation between exhaust and supply must be at least 3 feet.