Carrier VVT system

Wayco Wayne_2

I have been asked to upgrade and modify a 20 ton VVT system that has never worked well. One of the fist things I want to do is replace the bypass dampers used to control the static pressure with a variable Frequency drive to control the speed in response to the static pressure. I need leads to manufacturers and info on how it's done. thanks.

Techman

Carrier would be best

to be contacted and consulted. I took my VVT training thur our local Carrier distributor, and they also offer consulating services.

hheaddon

check out the whole system

Not knowing what generation of vvt you have, the first thing to do would be to get into the system,hopefully using carriers old dos based software and see what is going on.As one who still works on the old version's of this, making sure all the correct settings on all devices is critical.  Saying that it never has worked well could be anything from a equip problem,original design, and the most common i see is a changed loads in the building or trying to use vvt for a critical cooling load like a server room.  I still can find parts for these although they are not new, I find it,s still cheaper than trying to put in a new zoning system.Sooner or later a new system may be needed though and hopefully building loads redone.

Putting a vfd on a system that is designed to have a certain amount of  airflow across heat exchangers and coolling coils is not the best way to go unless the unit was originally designed for it.  Can you be more specific on the problems you have?

tim smith

Re: VFD

The latest generation of Honeywell vfds are quite nice, simpler programming than the old vfds and more compact

RJ_4

VFD

As I remember most VFD's take either a 4-20 milliamp or 2-10 volt dc input to operate, If I remember the old carrier (Parker) VVT systems worked off there own operating system, some type of com link. I dont think the VVT would interface with most VFD's   correct me if i am wrong

VA_Bear

V V T is a deticated communications protocol

but you could use an independent pressure transducer to control the VFD and maintain the static with the VVT signalling a digital on/off function. Are you sure you want to get into interfacing the two rather than doing a changeout of the controls?

Tim Doran_4

Controls FYI

Hey Wayne,



just an FYI, Taco can provide the VFD's and total VAV/VVVT control system. If you get into one of these and want some help let me know.



Tim