A big fan in an empty building is easy to picture. A big fan in your building, with racking, pallets and machines on the floor, is harder. That is where computational fluid dynamics (CFD) comes in. Before we supply and install a single fan, we can model your space and show you where the air will actually go.
The example on this page models one 20 ft Hunter Industrial Titan, using Hunter's published AMCA-certified airflow (155,756 CFM at full speed, 380-480V) as the fan input.
Why the floor matters more than you think
An HVLS fan drives a large, slow column of air to the floor, where it spreads out as a wide floor jet. That floor jet is what cools people. Rack rows, stacked product and equipment block and turn it, leaving dead spots behind them. In this example, the floor jet hits the rack row 15 ft from the fan center and stops there, and the area behind the rack gets much less air.
| Example demo result | A: clear floor | B: obstructed floor |
|---|---|---|
| Open floor area with air speed above 100 fpm at 5 ft | ~96% | ~79% |
| Distance from fan where the average floor-level (1 ft) speed falls below 200 fpm | ~58 ft | ~32 ft |
| Average air speed, floor to 6 ft | ~309 fpm | ~223 fpm |
Illustrative example room only. Not a Hunter or Big Fan Man performance claim; results depend on layout.
What the model shows that you may not expect
At working height, air near a wall exhaust fan can move away from it.
An exhaust fan pulls air in from every direction, so its pull falls off with the square of distance. In this example, air moved toward the 20,000 CFM exhaust at more than 50 fpm only within about 10 to 15 ft of the opening.
An HVLS fan pushes a focused jet that holds together. It drives a building-wide loop: down to the floor, out to the walls, up and back across the ceiling. At working height, that loop sets the air direction, even right below the exhaust fan. An exhaust fan does not pull air across the whole building. It controls how much air leaves, while supply openings and HVLS fans control where air moves inside. With the HVLS fan off, air mostly runs straight from the supply louver to the exhaust.
- Exhaust: place it where heat, fumes or dust collect.
- Supply: use openings and louvers to set the fresh-air path.
- HVLS: place fans so their loop works with that path.
What you get from an airflow study
- Fan placement you can see, so the floor jet reaches people, not racking.
- Exhaust and supply layouts that move air where it's needed.
- Clear pictures for owners and safety teams before money is spent.
Big Fan Man supplies, distributes and applies HVLS fans, wall and roof exhaust and supply fans, and creative air movement solutions.
