HVAC Chillers: Keeping Things Cool in the Data Center

This is the second installment of our series on data center equipment and maintenance. Among the types of equipment that require mechanical maintenance in a data center are HVAC chillers.

HVAC chillers are widely used in data centers to cool the water used for heating, ventilation, and AC units. Since these chillers often run nonstop, it is essential that they are well-maintained for optimal functioning. Without HVAC chillers, temperatures in data centers would quickly rise, causing malfunctioning of hardware and loss of important data. In addition, HVAC chillers make close-proximity servers possible.

It is also important to note that independent generators are essential for chillers in the event of a power grid fail.

Let’s break down some important numbers:

  • About 50 percent of energy in data centers will be used by IT equipment
  • About 35 percent will be used by HVAC chillers
  • About 10 percent will be used on electrical infrastructure and support
  • About five percent will be used on lighting.

Additionally, according to a report released in 2016, it is estimated that U.S. data centers account for two percent of the country’s total electricity usage, and they continue to grow! This means that the need for efficiency and decreased downtime is essential. It is also estimated that data centers consume as much energy as 6.4 million average American households.

Several methods of cooling servers are:

  • AC or air handler units (or, alternatively, CRAC units—computer room AC units)
  • hot aisle/cold aisle
  • hot aisle/cold aisle containment
  • liquid cooling
  • green cooling

Using simulation software such as SimScale to test out computational fluid dynamics (CFD) can be helpful in determining which method or combination of methods of cooling is best for your data center.

Some strategies for more efficient cooling of servers include:

  • Server layout
  • “free cooling”—using air from outside and allowing workers to dress for warmer weather
  • Locating data centers in cooler climates
  • Combination of cooling techniques

Here are some additional tips for maintaining optimal functioning of data centers and ensuring servers are kept cool:

  • Measure PUE (Power Usage Effectiveness). This value can be found by dividing the total data center power by the power consumed by the IT equipment. This will help you know if your current cooling system is effective or if you need to make adjustments
  • Be strategic about the airflow. A hot aisle/cold aisle layout of servers and airflow path is recommended.
  • Enclose components that emit cold and hot air so that the cold air doesn’t escape and can be utilized and so the hot air doesn’t undo the cooling of other units.
  • Whenever possible, utilize the natural environment and weather to cool your data center. This can also involve using water instead of chillers to cool servers.
  • Know what kind of servers you are cooling—different servers have different cooling needs.


Photo courtesy: iStock.com/BrianBrownImages

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