Determining which industrial fan size you need is typically done by determining the number of air changes per hour desired for your building's activities.
The number of desired air exchanges varies, but a general rule of thumb is below:
- 30 Air Exchanges is suitable for buildings people are frequently inhabiting.
- 20 Air Exchanges is suitable for animals
- 10 Air Exchanges is suitable for storage buildings
Let's use this example below to illustrate the calculations:
You have a building 50 ft. x 50 ft. x 20 ft., which is 50,000 cubic ft.
At a minimum, you want 4 air changes per hour.
|
(# of air changes per hour * volume of builing in cubic feet) 4 * 50,000 = 200,000 |
You'll then divide this number by 60 to get the Cubic Feet per Minute.
| 200,000 / 60 = 3,333 CFM needed to get 4 air changes per hour |
Now that you know your needed CFM, you can browse the Maxx Air exhaust fan line and look at the CFM ratings to find the unit closest to this value for your building. Maxx Air carries exhaust fans ranging from 14 inches to 36 inches in size, with CFM ranges from 1,400 CFM - 9,000 CFM.
| Exhaust Fan Size / Models | Max CFM |
| 14" / IF14, IF14RUPS | 1,400 |
| 18" / IF18, IF18RUPS | 3,000 |
| 24" / IF24, IF24UPS | 4,100 |
| 30" / IF30 | 5,500 |
| 36" / IF36 | 9,000 |
Don't forget to provide enough Net Free Air intake for your exhaust fan! You can provide intake either through opening doors and windows, or by using static ventilation installed on the opposite side of the building from the exhaust fan in the form of gable and wall louvers, soffit vents, and other static vents.
