I had this come up recently… what is a CRAC (pronounced ‘crack’)?  What is different from it than a CRAH (pronounced ‘craw’ or ‘cray’)?

CRAC = Computer Room Air Conditioner

A CRAC is often thought of as having an internal compressor, thus not needing the support of a centralized chilled water system.  But this also means it has to reject heat somewhere – like to a coupled rooftop drycooler.  A CRAC is also thought of as having refrigerant internal to the system, and with those extra motors and parts they need more maintenance care and have higher failure rates.

CRAH = Computer Room Air Handler

A CRAH is essentially a specialized air handling unit for computer room environments.  Most are a simple fan arrangement with an internal coil supported by a centralized chilled water system.

Clients may decide to go with one nomenclature or another, but knowing the difference can be important when working with design engineers, operations personnel and clients.

Posted in: Cooling, Standards

Filed under: Cooling, CRAC, CRAH