Cooling a Network Room: Airflow, Air Conditioning and Noise What changes once you have more than one rack. Part 2 of two. A single wall rack in a home or small office is a simple problem: ventilate it, keep it dry, keep it clean. Once there is more than one rack, the room itself becomes the cooling system, and a few new things start to matter. The reasons have not changed. Heat dries out the capacitors inside every power supply, and lead-acid UPS batteries lose half their des