Back in my systems contracting days, we were using Middle Atlantic MRK-4431 racks with up to 14 amps in them, no blanks in between. For large systems, amps were grouped together in 24's (14 in a rack, 10 in a rack, and so on). Again, no space between amps is necessary, IF:
- You have proper HVAC within the roomAND
- You have proper pressure in the rack.
That said, there was usually a good 12+" behind the amps (31" deep rack), and even if it was "full" with 14 amps, there was 10-16 spaces at the top for air to move. Also, rarely were there front doors on the rack, but almost always there was a solid back door. If there was a front door, it was a vented/mesh door.
With so few amps, I doubt you have a thermal issue in the room (unless there's some other BTU-belching device), so simply removing the front door of the rack should get you some relief. However, if you've got an EWR wall rack (16U?), there's probably very little way for air to flow through the rack. If removing your front door doesn't buy you a few degrees, it might be time for a larger, better vented rack.