VFD's in rooftop units

[Subcool215]

Just curious if anyone else has been having issues with VFD's installed in rooftop package systems on the blower motors?
They are becoming more common and now I believe the Government has made them mandatory.

I've been having some issues with them. Especially ICP units.

I feel that the VFDs being located in the blower compartment is too harsh of an environment. I know its probably the best option. But I've had a few recently have issues.
We all know that equipment owners don't always maintenance their units regularly. And I'm seeing the VFD's get affected by dirt. I even had a pizza shop that didnt change filters. The vfd had grease inside the heat sink!

I actually bypassed a vfd once because it was having intermittent problems. But the motor seemed to only run at half speed without the vfd.

Anyone else have any opinions about vfd's in rooftop package units?

[VTP99]

Yep got a 1 year old Carrier popping fuses intermittently.

[WAYNE3298]

In my opinion a VFD located directly in the airstream is nuts.

[Subcool215]

For whatever reason the motors won't run at Max Speed if if you bypass the vfd and wire line power straight to the motor. Does anyone know why that is?

[Spitz]

VFDs can run the motor up past 60hz. I have a few running past 60hz.

Sent from my SM-G960U using Tapatalk

[Spitz]

This was okay with tech support. I think there sales/engineer f-ed up. I needed more supply static. The fan curve allowed it. I ran it up till I hit FLA. been running for a few years. Bearings haven't blown up yet..........

Sent from my SM-G960U using Tapatalk

[Subcool215]

Thanks guys. Thats great info!

[WAYNE3298]

On bypass the motor should run at 60Hz.