Ducting question

[telcoguy]

Can you use multiple CRAC units or other cooling devices and duct the supply air to a single feed duct? I know you can use a common return but have not seen supply done that way. This would allow us to start with fewer units and add as we expand our footprint and heat signature. Looking at 30 to 60 ton indoor units. Thanks

[sgraefe]

It can be done, but I'd recommed that you add backdraft dampers to prevent the off line units from getting air blowing back thru them.

[Gib's Son]

I've done it. As stated, dampers are needed. I used mechanical dampers though. The thing you need to pay attention to is velocity in the ducts and at the diffusers so you get proper air mixture during low usage so the air does not just fall out of the diffuser resulting in spot cooling and not actual space cooling.