Skip to content

What’s the Most Common HVLS Fan Installation Issue?

A High Volume, Low Speed (HVLS) fan is a powerful piece of equipment that can provide cooling for some of the biggest commercial and industrial spaces that need temperature regulation. Given their size, you’d probably expect there to be a few issues that crop up with these fans if they aren’t installed, configured, and maintained properly. And you’d be right.

There are several things that can go wrong with an HVLS fan if you don’t install it the right way. We have found that far and away the most common issue with HVLS fans is determining where to put the fan’s variable frequency drive (VFD).

What is the Variable Frequency Drive?

The variable frequency drive on an HVLS fan is what regulates the fan’s operation by varying the level of power that is sent to the fan’s motor. It is what determines how fast the fan can run.

As you might imagine based on this description, a fan’s VFD is critical to the way that it runs. If your fan’s VFD isn’t placed properly, it can put a strain on the way that it communicates with the fan’s motor, void your warranty, or cause the fan to overheat.

The Importance of VFD Placement

The placement of your variable frequency drive depends on the specific fan you are installing in your facility. Each manufacturer creates its own guidelines based on the size and voltage of the fan: make sure to follow these installation guidelines exactly.

Why is VFD placement such an important concern? If your drive is not placed far enough away from your HVLS fan, it creates a phenomenon known as voltage overshoot. Put simply, voltage overshoot is when the electric signal from the VFD to the fan itself surpasses the normal capacity of the fan. This can cause a serious strain on the fan’s motor: in fact, it’s possible for an improperly placed VFD to cause the fan’s motor to sustain heat damage. In the worst cases, this heat damage will render the fan unusable.

Other fan manufacturers have tried to overcome this harmonic issue by placing the variable frequency drive on the fan’s gearbox. This can prevent voltage overshoot issues, but the problem with this approach is that it creates heat problems. Additionally, this makes the fan’s VFD harder to access. For example, when your drive needs to be reprogrammed, it’s much tougher to do so if it is located right next to other critical components of the fan.

How MacroAir Solved the VFD Problem

When installing our legacy fans, including the AirSpan and the AirVolution, we instruct our users to place the fan’s VFD within 25 feet of the fan’s motor. Any further away than this distance and the warranty will be voided, unless you receive explicit permission from our customer support team to place the VFD further away.

With our newest Direct Drive fan, however, we’ve totally eliminated the challenge of variable frequency drive placement. That’s because the VFD on these fans has been replaced by sophisticated AirBrain processors. The AirBrain on the direct drive is built into the fan, which minimizes the fan’s footprint and uses a gateway to integrate into the operation of the fan. Cooling the processor with centrifugal cooling through hollow end caps eliminates the heat issues and taking away the VFD also takes away the challenge of placing it.

The Bottom Line

Placing an HVLS fan’s variable frequency drive incorrectly can void your fan’s warranty or cause serious heat damage. To avoid this issue, be sure to carefully follow the manufacturer guidelines regarding VFD placement, or choose a sophisticated HVLS fan like the AVDX, which makes placing your variable frequency drive a non-issue.