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How to use the Commercial Kitchen Exhaust Hood Calculator

Adrienne Gould-Choquette, P.E. · · Commercial Kitchen Exhaust Hood, HVAC Engineering

This article and video demonstrate the use of the Commercial Kitchen Exhaust Hood Calculator.

The video and screenshots show the earlier version of the calculator. The current one works the same way, and its results update as you type.

You can find all of our calculators on the calculators page, grouped by category.

The calculator page explains how to use it, and each hood needs its own analysis. So let's get started.

This demonstration is based on a project I am currently working on. It is in the US, so we will select US units. The client specified a wall-mounted canopy, so we will choose that hood style. The calculator page summarizes the differences between the hood styles, from ASHRAE.

This exhaust hood is KEF-1 in our demonstration kitchen. The calculator page also describes the hood types; our application will be a Type I hood.

The client provided a kitchen layout with the following equipment under the hood:

  • 30" Range, hot top, gas

  • 36" Griddle, flat, gas

  • 48" Fryer, open deep-fat, gas

The equipment is grouped by kind (broilers, fryers, griddles, ranges and so on). Select the equipment type from the list and enter its length in inches. To add another piece of equipment under the hood, press "Add appliance". Enter all of the equipment.

After the equipment has been entered, there is one more optional input. If the design also includes a make-up air unit, enter the make-up air as a percentage of the exhaust.

The results give the linear feet of equipment and subsequent required linear feet of the hood. It also gives the exhaust rate per the International Mechanical Code, the exhaust rate range per ASHRAE, and the matching make-up air volumes where they apply. Based on your inputs, there are also some notes from ASHRAE, the Florida Building Code, and the International Mechanical Code.

Back to the project, this is a small restaurant, and the most significant load is the outdoor air required to keep the building in balance. The restaurant owner decided to reconfigure the kitchen and switch to a Single Island Canopy. I advised my client that changing hoods would increase the required hood flow rate (and make-up air) from 3,150 CFM to 5,250 CFM and was not practical based on their restaurant's space constraints and budget.

  • HVAC Engineering
  • Commercial Kitchen Exhaust Hood
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