Behind the server racks
If this is after, the 'before' must have been terrible. The cold air is supposed to be drawn through the racks by the servers, and then the hot air at the back cooled and returned to the front. If you put all the sides on the racks and construct some screening around the racks you will get much better airflow and more efficient cooling.
Have a local A/C guy check it out and see if the air handler unit can be flipped upside down. Meaning: Pull air in from the top and push it out the bottom. Then, install the duct work out around the baseboard area and put registers to distribute the air directly to the equipment. The net affect would be putting the cool air low to the floor and let the warm air naturally rise to the ceiling. That would take advantage of the room air's natural circulation. Depending on the space, putting the cool air out at the ceiling is not the most efficient way to cool equipment. It's normally routed out the ceiling in a house to circulate the house air as the cool air falls and the warm air rises (mixing the air).
the labeling on the cable had better be good, a recent job I had used a similar system only to have the tags fall off after a few years. My job was to add patch panels to connect the server room to the cable room. About 400 cables with most of the tags on the floor.
Not your fault, Scott, but the AC is, as usual, upside down. This is old-time, 'energy is cheap, let's do it the easy way' design. It is ridiculous to think that it is efficient to pull cool air from the floor area, cool it more, and pump it thru' the hot air at the ceiling. The hot air up high should be cooled and pumped out at floor level, where cool air wants to be anyway.
The duct work is a nightmare. Wrong on so many levels. I noticed Westminster does not have an Engineering department. Explains it all.
Good job, Scott, I know the challenges of trying to do a complete makeover on a system that needs to stay up and running. I am sure that when you can dig in with that wiring that troubles you, it will satisfy the most OCD afflicted admin! Keep up the good work!
Make sure you leave plenty of ventilation above the ceiling to prevent condensation forming on the uninsulated duct. I have seen this done before and can become a real problem if the area that the duct is running in has warm stagnate air. This might not be apparent until the weather warms up and humidity levels rise.
I'm in the same boat RIGHT now. :) Redoing the cabling of an old network at our site to extend it to a new rack mount location. Hardly any of the original cables were labled. It's been a combination of 'poke and hope' and wearing out the batteries on the tone generator. :)
When funding permits, this unit and the ductwork are going away. That unit was installed a few years ago and apparently was the "budget-conscious" choice at the time. And, we WILL be getting an HVAC person for that! Scott
Sorry to be so critical, but I have agree about the nightmare duct system. I don't know why they had to strip the insulation off the branch lines it doesn't take up that much room. It really does need to be done over, though that might be too late now since it appears that the ceiling is blocked with cables. I see another potential disaster with the drain line. They are using a condensate removal pump, these are notoriously known to stop up and quit working at the worst times. Unless the alarm circuit is hooked up and a signal is sent to the network admin, or a shutoff control to the condensing unit the room will flood in no time. You can't depend on the alarm circuit, most of them are just a flimsy as the pump itself. At the minimum a free flowing floor drain should have been installed with a "P" trap or not have the air handler in the room at all. I know its too late to change the location of the air handler, but maybe some of the modifications like an alarm and a complete redo of the duct system. I know the trunk line is a poor design too, but the rest of it looks typical as far as a server room goes. A competent HVAC engineer needs to evaluate this situation before disaster strikes!
Formerly, commercial and institutional entities used liquid-cooled condensers for cooling. These are more efficient, tho' potentially higher first cost. There seems to have been a movement away from them. Give them _serious_ consideration for your new center.