Coolant distribution units can complicate commissioning

The goal of commissioning is to prove a data center’s readiness to support the IT load at design capacity by demonstrating and documenting the performance of power and cooling systems. Direct liquid cooling (DLC) presents challenges at all stages of commissioning, in part because it physically couples facilities and IT equipment in new ways. Best practices for commissioning liquid-cooled mission-critical environments are still maturing.

Coolant distribution units (CDUs) are at the center of the issue. The commissioning of CDUs and the connected equipment in the technology cooling loop is not always straightforward for a range of reasons. Some manufacturers of CDUs have (or used to have) limited experience with either the minutiae of integrating and testing a CDU in a larger, complex fluid network, or the wider data center commissioning process. Some of these companies had not sold any products to data centers before introducing their CDUs. This does not imply that the manufacturers cannot build a performant and reliable product — but factory witness testing (FWT) of their CDUs to verify their capabilities under real-world conditions is crucial.