There are fundamental differences between standard (Comfort/Commercial) and Precision air conditioning (Equipment)…reasons why “people coolers” won’t protect equipment. People are far more tolerant of temperature and humidity swings, whereas equipment requires precise levels of temperature and humidity maintained around the clock. This means heavy-duty systems and precision controls are required; people coolers don’t have either the strength or sensitivity for the job.
Following is a list depicting differences in detail:
1: Year-Round Operation
Commercial cooling systems are designed to operate only during normal working hours. Equipment sites, however, generate heat 24 hours per day, 365 days per year, and so the cooling equipment must be able to operate reliably in all conditions.
2: Electronic Load
The primary loads in commercial sites are normally people and ventilation air whereas in Precision Air Conditioning sites, it is normally Equipment. In the process of cooling, comfort air conditioners cool the air (sensible cooling) and remove moisture (latent cooling). Since electronic equipment does not release or absorb moisture, the air conditioner selected for an Equipment cooling site should primarily cool the air, not remove moisture. The air conditioner should normally be selected with a “sensible heat ratio” of no lower than 95 percent. In a commercial air conditioner this ratio is not more than 65% that leads to wastage of capacity in terms of CAPEX & OPEX.
3: Temperature Control
The high-density heat load in an Equipment room is beyond the capacity of comfort air conditioning systems. Equipment is best maintained in a stable environment of 22.2 deg C /-1 deg C). As equipment generates large quantities of heat in small areas, six to ten times the heat density of normal office space, the air conditioning system must have more than just enough cooling capacity. It must have the precision to react quickly to a drastic change in heat load and prevent wide temperature fluctuations, which is something a comfort air conditioning system cannot do.
4: Humidity Control
Equipment must be protected from both internal condensation and static electricity discharges. Maintaining the correct humidity level in the Equipment room is just as important as maintaining proper temperature. Too high a humidity could cause condensation within the telecom equipment and the potential for hardware damage. If humidity is too low, static electricity could disrupt operation or even shut down the telecom system. A comfort air conditioning system cannot normally control the environment within these boundaries.
5: Air Volume
Equipment requires greater air volumes than ordinary air conditioning can provide. Typical comfort systems are designed to provide between 300 and 400 CFM (cubic feet per minute) per ton of cooling. Equipment require between 500 and 600 CFM per ton. The high-density heat load in a relatively small space requires more changes of air than a less dense “comfort” application. While a normal office space requires only two air changes per hour, an equipment room requires up to 30 changes per hour. Without proper air volume, hot spots and temperature fluctuations could develop within the space.
6: Air Filtration
Filtration of both room pressurization and recirculation air is critical in a communications site, and the air filter should have an “ASHRAE 52-76” Standard Efficiency of no lower than 25 percent. This efficiency is much higher than normally provided in a commercial system.