This past week, while visiting data centers in Michigan, we discovered that one of our customers was in the midst of deploying about ten CRAC damper/extensions on their legacy floor units. The customer had upgraded their cooling system to have rooftop units ducted to the raised floor, but kept the floor units around for backup. Upgrading cooling systems is a normal part of a datacenter’s lifecycle, but our customer was running into a few problems during the process. Their issue was that these existing floor units effectively acted as “big holes in the floor” that allowed air to leak back through them and into the room.

This same problem is sometimes associated with the deployment of either hot or cold aisle containment in legacy sites where the goal is typically to turn off CRAC units (those not equipped with VFDs). However, once a CRAC unit is turned off, it effectively becomes that “big hole,” leaking cold air back through the unit and reducing the efficiency of the data center’s HVAC system. In the past, Polargy has offered CRAC Covers to help prevent that leakage, which is fine when units are manually turned on and off. The covers won’t work for CRAC units that are remotely controlled on and off such as those connected to a DCiM, for obvious reasons. This is the case for our customer in Michigan. So, what can be done?

CRAC Damper Top Mounted

Dampers can become the solution for this problem. CRAC Dampers are custom built to the size of the unit and the height is also specified for each individual project. These are delivered as large, rectangular boxes and are simply attached to the tops of the units with sheet screws. Since the damper assembly impedes access to the CRAC unit from above, filters are installed above the dampers on flanges that are built into the extension. The easiest and simplest way to add dampers to an existing CRAC unit is to mount gravity operated dampers to the tops of the units. This is exactly what our customer was doing during our visit. The damper housing was about 18” tall to also act as an extension, grabbing hotter air from higher up in the room.

Gravity Operated Louvers

Just like our Michigan customer, check on your CRAC units. If you know they will be manually controlled, CRAC Covers can be a good solution. For the CRAC units connected to a monitoring system that dynamically controls them, dampers are the way to go.