Quote Originally Posted by George2 View Post
You need 5 full outlets per ton. I try to even the load between the two 7" runs. The 3rd floor with only the 6 supplies can't be that large of an area. Arzel Zoning has zoning for high pressure systems. Give then a call.
Designed correctly and Installed correctly zoned Small Duct High Velocity systems can work great , First and foremost the system needs to be installed following the OEM manufactures recommendations , transitions , plenum and trunk design need to be followed exactly .

Then we recommend on single stage stage units to have 3.5 outlets per ton on EACH zone as a minimum . For 2 stage equipment 2.5 outlets per ton / per zone minimum .

I also always recommend checking the system "Full Open" static and motor amps per the OEM's blower performance chart , if you are "barely moving enough" or "not moving enough" air with the system wide open and you are zoning it , then you can expect to have issues . An "Outlet" is only an "Outlet" if it is moving enough air , in other words you may have the "specified" number of outlets on your system to zone SDHV but if your system is already running high static and low motor amp's wide open , then closing a zone is going to be an issue .

In addition there can only be 2 or 3 Zones max with no bypass on DX Systems . Chiller systems we have more flexibility .

You can feel free to contact me if you have questions or would like information on our complete SDHV Zoning considerations .