I am looking for some help in deciding what to do with a server closet I have in my San Diego, California home. This server closet has one half-height rack in it. I read a number of posts in the forum and am not clear what I should do.
First, in terms of cooling needs, I estimate just over half a ton. Here is how I came up with that figure. The rack has two Dell servers (4,600 BTUs/hour), a switch, modem, and hardware firewall box (estimated total 400 BTUs/hour), and an APC rackmount UPS with two additional battery packs (estimate 300 BTUs/hour since the UPS usually acts like a power strip). I also have a printer sitting on its own stand that generates 1,200 BTUs/hour in the closet. All total I have 6,500 BTUs per hour.
The closet is part of a 380 square foot, one-story room. The closet itself is 12 feet long by 3 feet wide by 9 feet tall. In addition to the server rack I have three metal file cabinets (two in one corner, one in the other). The closet has two sets of double-doors, (4 total doors), all 8 feet high. We installed a 150 cfm bathroom fan in the ceiling above the back of the rack. The fan is connected to a thermostat and turns on when the closet temperature exceeds 80 degrees. The main part of the 380 square foot room is cooled by a dedicated 2-ton Fujitsu Halcyon heat pump. I have such a large unit for the room to take care of the server closet's cooling needs.
Now for my problem. Unless I open all the doors to the closet, the temperature in the closet can rise to 85+ degrees. I am concerned that once summer hits, the temperature could exceed 90 degrees. I do not want to leave the closet doors open because of the noise and aesthetics. I also cannot install a separate AC unit for the closet. The 2 ton Fujitsu needs to provide all the cooling.
I have been getting conflicting advice. Several people including my HVAC person said the 150cfm exhaust fan is likely pulling far less air when the doors are closed. He suggested I open up vents in the bottom of my doors to allow more air into the closet (so the fan would be more effective). I have also been told to look into Middle Atlantic's Quiet-Cool closet cooler (http://www.middleatlantic.com/rackac/cooling/qcool.htm). It has two vents, one that installs at the bottom of the door and another that installs at the top of the door. The bottom vent has an active 50 cfm fan that pulls cool room air into the closet. The top vents has another 50 cfm fan that blows hot closet air out into the main room. Other options include installing one or more fans in my rack to blow air through the rack (http://www.middleatlantic.com/rackac/cooling/uqfp.htm), and installing a second 200 cfm exhaust fan in the other end of the closet that would vent to the outside.
Can anyone tell me which way would be the best alternative? I tried to paint a complete picture, but please let me know if you have any questions.