What Is a CRAH?
A Computer Room Air Handler (CRAH) is a cooling unit used to regulate the temperature and ensure optimal operating conditions for IT equipment. CRAH units are essential for cooling central IT infrastructure, ensuring stable and reliable operation of critical equipment. The CRAH unit is used in electrical rooms to cool power and network equipment in colocation and hyperscale data centers. The CRAH is also used in the white space and acts as supplemental cooling alongside chilled water systems.
How Does a CRAH Work?
Unlike computer room air conditioners (CRACs), a CRAH does not have its own internal compressor or refrigerant. Instead, it relies on a central chiller plant, such as a high-efficiency Trane air-cooled or water-cooled chiller, to supply chilled water.
- Air intake: Hot exhaust air from the servers is drawn into the CRAH unit by its internal fans.
- Heat exchange: The hot air is passed over a cooling coil filled with chilled water from the central plant. A modulating valve precisely controls the flow of this chilled water to match the exact cooling demand of the room. The chilled water absorbs the heat, and the newly cooled air is discharged back into the data center, electrical room or white space.
- Air distribution: Electronically Commutated (EC) fans to dynamically speed up or slow down airflow based on real-time data center heat loads.
Benefits of using CRAH
There are several benefits to including CRAH units in your data center HVAC system:
- Energy efficiency: Because CRAHs do not use internal compressors, they draw less power. When paired with a highly efficient central chiller plant that utilizes free cooling, they contribute to significant energy savings.
- Lower in-room maintenance: Because all the complex refrigeration components are kept outside or in a mechanical room, routine maintenance inside the secure data hall is drastically reduced.
- Scalability for high-density loads: As rack densities increase, a central chilled water system can efficiently distribute massive amounts of cooling capacity to multiple CRAH units.
- Precise climate control: CRAH units provide the tight, continuous temperature required by sensitive servers and networking gear.
- Redundancy: To maintain critical uptime in data centers, CRAH units are often part of a redundant system, ensuring if one unit fails, others can maintain the necessary environmental conditions.
For efficiency, scalability, and reliability, computer room air handlers are a critical component in data center cooling systems. To learn more about these units, contact your local Trane representative today!
