Fan Variable Freq Drive - Energy Savings

[new2hvac]

I'm trying to estimate the energy savings that will be seen by installing a variable frequency drive on (2) 50 hp supply fans.

I've reviewed some software provided by a VFD manufacturer, but they only show energy savings of a VFD versus Inlet Guide Vanes and Outlet Dampers (which incidentally matches very closely with ASHRAE's estimates). In this particular case, the airflow is varied with a diverting cone at the inlet of the centrifugal fan.

I've not personally seen the cone...is anyone familiar with this type of system? Does anyone have an idea of how efficient these cones are compared with IGVs or outlet dampers?


Thanks!

 

[fredt]

I've never heard of a diverting cone, it sounds like some kind of throttling device but in any case is not a conventional way of controlling fans. It is likely to be similar to outlet damper. Inlet louvre dampers are also used which are about mid way in efficiency between radial inlet vanes and damper throttling.

 

[absrbrtek]

A Varicone and inlet guide vanes perform the same function. Both regulate the supply air going into the fan. I dont know your actual energy savings but wear and tear on the motors, belts and bearings will be decreased signifigantly using the VFD.