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HVAC Forums => HVAC Help => Topic started by: Sergroum on December 27, 2016, 12:25:07 PM

Title: High Velocity
Post by: Sergroum on December 27, 2016, 12:25:07 PM
Heya everyone.

I've never installed a high velocity system. I've serviced a few, but to my admitted stupidity, never spent enough time observing the nature of installation itself. Now I'd like to install one and I could use a bit of help and advice.

The system I'd like to install is cooling only. Basically a compressor, coil, and an air handler enough for 1.5t installation. That part is simple and easy enough. What I am concerned with is the ducting. What should be the size of the plenum for that thing. Most of these air handlers are going around 600-700 CFM if I recall correctly. I unfortunately do not have enough experience with high velocity,so I fear I'll mess up on static pressures. I imagine the system needs 8 outlets per ton, going via those 2 inch inner diameter tubings, but what should the original plenum be like? How big should the return be for adequate operation? Almost 90% of all of my service calls on these systems revolved around not having proper airflow. I'll be damned if I end up doing the same silliness. Any advice, or a point in the right direction to research the matter would be highly appreciated.
Title: Re: High Velocity
Post by: bster352 on December 30, 2016, 09:55:24 AM
Check this Unico link https://www.unicosystem.com/the-system/design-and-installation/ (https://www.unicosystem.com/the-system/design-and-installation/)
Title: Re: High Velocity
Post by: walker on December 30, 2016, 08:33:05 PM
Most of the 1.5T I see are rated for 550CFM (Temp-Mizer, Flex Energy, Energy Savings), its no wonder air flow is always a problem on the cooling side, that and the builder puts in 8 supply lines, when at least 12 are required.