What is the Difference Between CRAC and CRAH Units?

Telecommunication equipment with many cables, switches and air conditioners in a modern communications center. Heinz Mechanical serving Portland OR and Vancouver WA talks about what the difference is between CRAC and CRAH units.The difference between a CRAC (computer room air conditioner) unit and a CRAH (computer room air handling) unit is that a CRAC unit uses refrigerant and a compressor, whereas a CRAH unit uses chilled water and a control valve to provide cooling.

Used to cool data centers and network areas that generate a lot of heat, CRAC units and CRAH units can mean the difference in how your computer systems perform.

CRAC Units

CRAC units work just like the air conditioning units in your home. They have a direct expansion system and compressors built right into the unit. They provide cooling by blowing air over a cooling coil filled with refrigerant. The refrigerant maintains its cool state by a compressor within the unit. Excess heat is then expelled by a glycol mixture, water, or air. While most CRAC units generally provide constant volume and only modulate on and off, newer models are being developed that enable airflow variations.

There are various ways of how your CRAC units can be situated, but they’re typically installed opposite of the hot aisle in a data center. There, they’ll release cool air through perforations in the raised flooring, cooling your servers.

CRAH Units

CRAH units function like chilled water air handling units installed in most skyscraper buildings. They provide cooling by blowing air over a cooling coil filled with chilled water. The chilled water is typically supplied by, “The Chiller” — otherwise known as a chilled water plant. CRAH units can regulate fan speed to maintain a set static pressure, ensuring the humidity levels and temperature remain stable.

CRAC and CRAH Sizing

Servers can generate a substantial amount of heat. In fact, a single rack of servers can easily generate over 100 degrees. But you also have to keep in mind the size of your unit. Get a unit too large, and you’ll experience static discharges and condensation, get one too small, and you’ll suffer thermal over-runs and reboots.

Heinz Mechanical offers various sized CRAC units and CRAH units to fit your business’ needs. Contact us today for more information about our temperature and humidity control units.

Contact Heinz Mechanical today to learn more about our CRAC unit installation services. We look forward to putting our years of experience to work to solve your needs.

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