Adding Efficiency Hoods to CRAC Units in the Data Center

 
Keeping a growing data center nice and cool is always one of the goals and challenges for a hosting company.  As it stands Hivelocity is n+1 on computer room air conditioning and our data center is maintained at 72 degrees fahrenheit.  While the temperature in the data center is always cold and we have a ton of air flow, there are definitely things we can do to make the facility more energy efficient.  One of the simple ways to improve efficiency is to ensure the CRAC unit returns are sucking in hot air and not cold air.  Of course, we all know that hot air rises so logically the best place to pull hot air from is near the ceiling.  Out of the box our Leibert and DataAire CRAC units come with their hot air returns at the top of the units and blow cold air from the bottom into the raised floor.  That cold air is then pushed out of strategically placed perforated tiles throughout the data center.   The problem is the CRAC units are only about 6 feet tall so the returns are sucking whatever air is sitting at 6 feet.  The drop ceiling in our facility is 10 foot so out-of-the-box the CRACs are not getting the hottest air possible and up until last week were actually sucking in some nice cold air.  Believe it or not, the hotter air you get into those returns the colder the air coming out will be.  Pulling in cold air is counter productive and warms up the data center.
 
Last week we completed the installation of efficiency hoods on the top of each of our 22 and 30 ton CRACs.  These hoods were custom designed specifically for our data center.  These hoods add another 2-3 feet of height to the CRAC returns, depending on if ladder racking happens to be directly above the unit or not.  By simply adding these 2-3 feet we are now pulling the hottest air possible out of the data center.  Of course when you start pulling out more hot air, the overall temperature of the data center gets cooler and cools faster.  The addition of  these hoods has lowered the temperature of our cold aisles 1-2 degrees while allowing the CRACs to cycle off more frequently, thus adding to the life span of the units.
 
So for a minimal cost and without adding one electronic device, we were able to lower the data center temperature, increase our energy efficiency, extend the life of our CRAC units and lower our power bill.  Not bad for a few hours of install time and very little sweat.