Which one of the following is an advantage of Glycol Cooled System?

A primary advantage of a glycol-cooled system is its architectural flexibility and scalability. In this design, a central chiller plant cools a water/glycol mixture, which is then pumped through a closed-loop piping network to multiple Computer Room Air Conditioning (CRAC) or Air Handling (CRAH) units. This fluid can be transported efficiently over much longer distances than the refrigerant in a direct expansion (DX) system. This capability allows a single, centralized cooling plant to serve numerous cooling units spread across a large data center floor, making it an ideal solution for medium to large-scale facilities where heat rejection equipment must be located far from the IT space.

A. Glycol systems involve significant capital costs for chillers, pumps, and extensive piping, making them more expensive initially than simpler systems.
B. The glycol/water solution requires regular maintenance to monitor and maintain proper concentration, pH levels, and corrosion inhibitors.
D. While true that they are used in big data centers, this is a consequence of the advantage described in option C, not the fundamental advantage itself.

1. Schneider Electric, White Paper 59, "The Different Types of Cooling Systems for Data Centers," Rev 1 (2011).

Page 4, "Glycol-cooled (split) system": This section explicitly states, "This system is used when the distance between the indoor unit and the outdoor heat rejection unit is too great for refrigerant piping... The glycol-cooled system allows for much longer distances between the indoor CRAC unit and the outdoor dry cooler." This directly supports the correctness of option C.

2. ASHRAE TC 9.9, "Thermal Guidelines for Data Processing Environments," 4th Edition (2016).

Chapter 6, "Data Center Cooling Systems": This chapter details various cooling architectures. It describes how chilled-fluid systems (including glycol) are inherently scalable for large data centers precisely because the cooling medium can be piped over long distances from a central plant to distributed air handlers, a key design advantage over distance-limited systems.

3. Uptime Institute, "Data Center Site Infrastructure Tier Standard: Topology," (2018).

Section 6.0, "Mechanical Systems": The standard discusses the components of concurrently maintainable and fault-tolerant cooling systems, which often rely on piped distribution networks like chilled water or glycol. The ability to create redundant piping paths over the long distances required in Tier III and IV facilities is a core benefit of this technology, reinforcing the advantage stated in option C.