Dual Fan Frequency Drives on Central Duct

[Waunakee]

I am trying to locate information on controlling two frequency drives (one on each) of two Trane Intellipak Roof Top Units. The current situation of them being seperated causes one fan to "overcome" the other, i.e.: 70% compared to 30%. What is the best way to resolve this issue - anyone with experience on this issue?
Thanks,
Kevin

 

[ChasBean1]

Kevin, for controls and drives, this is a question for the Trane rep. Last I knew, Trane has packaged controls/ sensors/drives, etc. (although this may not be the case with your system).

To balance drives, a simple solution might be to just tee the two units' pressure sensing tubes together. With this done, each unit's drive will try to maintain the average pressure. -CB

 

[DouginMB]

Do both drives need to operate at the same time?. It might be that the return fan drive can drop off below a minimum static pressure and the supply fan drive can pick up the slack. If the unit has mixing louvers, they can be controlled as needed to maintian minimum ventilation airflows and space pressurization.

If Trane provided the drives, they are probably Sqaure-D drives. You might want to contact the Square-D rep. They have pretty good tech support for their drives.