Placement That Improves Cooling
Server rooms demand strict control of temperature, humidity and cleanliness, so dedicated computer-room air conditioners (CRAC) differ greatly from comfort units, and their layout strongly affects cooling.
Layout Guidelines
- Face units toward the hot aisle, not the cold aisle, to keep under-floor dynamic pressure low.
- When placed in parallel, aim supply so floor static pressure rises rather than causing flow conflicts.
- Clear hot-air return paths lower rack inlet temperatures.
- Separating cold supply from hot exhaust is the key efficiency measure.
- Control supply temperature, not return temperature, for stable IT inlet air.
- Uniform under-floor flow needs same-direction supply; colliding jets give poor distribution.
- Vanes cut airflow about 15%; avoid them unless needed for paired units.
Five Differences From Comfort AC
- Sensible heat exceeds 90%; CRAC uses high airflow and low enthalpy difference, avoiding static from over-dehumidification.
- High air changes (30โ60/h) give even whole-room cooling.
- Better filtration keeps the room clean.
- Runs continuously, year-round, and still cools in winter.
- Adds humidification, dehumidification and electric reheat for precise control.