Cooling solution for 3 rack shop

[BillP]

Hey All,
Long time listener, first time caller. We bought a new rooftop unit here a couple years ago, and I used the calculators on the site to spec it at 3.5 tons based on future growth etc. Well 2 things have happened since then. 1) we have had issues with the unit where parts have failed, etc causing some downtime. We are looking at some kind of other option to give us some redundancy. I wondered if any of the APC solutions could work for us. Or if we are better off just buying another rooftop unit and having one thermostat at 71 and the other at 68.
The 2nd thing that has happened is the server room itself isn't that insulated so on the RARE hot (90 F + ) day in Oregon our unit sometimes can't keep up, so if we did get some other product it would be nice for it to kind of kick in when needed. Again are we better off with second roof unit? We have a Lennox T class unit, and I am not sure if you can link two of them together and have some kind of smart redundancy?

Thanks!
-Chris

[BillP · Accepted solution]

Chris what would be your current and maximum projected load in each rack (kw)? UPS size and current load?

It seems you are using a comfort HVAC to cool critical IT load that would explain some of the issues you mentioned.

Proper cooling should take into account unit capacity, airflow and how you manage hot air, this all depends on nature of load, rack layout and best practice design techniques.