Have Fun With CRAC (Computer Room AC)

HVAC School - For Techs, By Techs

In this episode of the HVAC School podcast, Bryan interviews Pat Ward, an HVAC technician who specializes in servicing and maintaining computer room air conditioning (CRAC) units for data centers. They dive deep into the unique challenges and setups involved in cooling these critical facilities.

Pat provides an overview of data centers, explaining that they are essentially industrial-scale computer rooms that generate immense amounts of heat from the servers and need precise environmental controls. CRAC units are specialized air conditioning systems designed to maintain the temperature and humidity within tight parameters suitable for electronic equipment.

Unlike typical comfort cooling, CRAC units supply air around 70°F to avoid excessive dehumidification. Humidity control is crucial, often requiring supplemental humidifiers or dehumidifiers. Pat discusses common configurations like air-cooled direct expansion (DX) units as well as chilled water systems with computer room air handlers (CRAHs). Redundancy is a major consideration, with units networked together to stage capacity and provide backup.

The conversation covers many other topics related to data center cooling such as:

• Using economizers and free cooling with outdoor air when conditions allow
• Potential issues with mildly flammable refrigerants in these applications
• Typical maintenance tasks like coil cleaning, filter changes, and refrigerant checks
• Accessing and navigating the control systems which often require passwords
• Advice for technicians new to working on CRAC units, like studying the equipment layout
• The massive scale of large data center installations with arrays of 20+ CRAC units
• Causes of overheating and how to avoid them
• Growth opportunities in the CRAC niche of HVAC

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