Exhaust Fans & Make-Up Air

Exhaust Fans
Exhaust fans move the heat and contaminated air out of the building. All exhaust fan components must be accessible or have removable access panels for cleaning and inspection and must be designed to contain and drain any excess grease.

There are 3 major types of exhaust fans:
  • Up-blast fans are typically aluminum centrifugals that are designed for roof mounting directly on top of the exhaust stack.
  • Inline fans are typically located in the interior duct and are used where exterior fan mounting is impractical.
  • Utility fans are normally roof-mounted with the inlet and outlet 90 degrees from each other and are typically used where high-static pressure losses exist.
Automatic Operation
Type I hood systems shall be designed and installed to automatically activate the exhaust fan whenever cooking operations occur. The activation of the exhaust fan shall occur through an interlock with the cooking appliances, by means of heat sensors or by means of other approved methods.

Termination Locations must also be considered. Please refer to the Indiana Mechanical Code for exhaust fan termination location requirements. The height and distance of an exhaust fan to other air intake or adjacent buildings is often overlooked.

Make-Up Air
An effective commercial kitchen ventilation (CKV) system requires air balance. Unlike a cooking appliance, which can be isolated for troubleshooting, the exhaust hood is only 1 component of the kitchen ventilation system. Makeup air shall be supplied during the operation of commercial kitchen exhaust systems that are provided for commercial cooking appliances. The amount of makeup air supplied shall be approximately equal to the amount of exhaust air.

For mechanical makeup air systems the makeup air system shall be automatically controlled to start and operate simultaneously with the exhaust system.