There are multiple issues related to controlling the air intake temperature that reaches your IT equipment, however, they generally fall into two major areas. The first is the method of controlling the supply air temperature that leaves the cooling units. The second is controlling the airflow to avoid or minimize the mixing of supply and return air – before it enters the IT equipment.
One of the most common methods of temperature control in data center cooling systems has been traditionally based on sensing the temperature of the air returning to the cooling units. The temperature is typically set and controlled on each cooling unit individually. Based on this, when the return air temperature rises above the set-point, this simply causes the unit to begin the cooling cycle. Therefore in most systems, if set for 70°F, the cooling unit would then lower the temperature by 18-20°F, resulting in supply air temperatures of 50-52°F.
This simple return temperature based control method has been used for over 50 years. Nonetheless, this inherent drawback has essentially been overlooked by most facility managers, and was and still is considered a normal and “safe” operating practice for most data centers. This wastes energy and despite the very low supply air temperatures, it does not really ensure that the IT equipment ever received enough airflow or that it was within the recommended temperature range, primarily due to poor airflow management issues.
To read the full article, view it on the Data Center Frontier website here.