Cooling for a small server room

I have a server room about 12 feet square with an unfinished ceiling (exposed ducts and wiring). It houses a few servers (about ten, 1U and 2U) and some networking gear (four 1U switches, three routers, three modems, two cable boxes).

With the door closed, it runs around 80 degrees Fahrenheit with half the servers turned on. When I turned on all the servers it reached 86 before I chickened out and propped the door open.

The room is adjacent to air-conditioned office space, but does not itself have dedicated air conditioning. The ventilation for this room seems to be limited to one duct coming in at ceiling level, with a powered fan to draw air in, and one duct at ceiling level to allow air to flow out (it seems like it may just go into the drop ceiling cavity in the adjacent room).

The adjacent office space stays fairly cool, but I'd prefer not to leave the door propped open all the time.

There is both 110v and 208v service in the room, and plenty of power available. But there are no windows, and no floor drains (in a pinch we might be able to run a condensation hose through a small hole we'd drill in the wall to a nearby sink area, but only if absolutely necessary).

I've considered portable A/C units, but I'm not sure on sizing and a lot less sure how we would run the exhaust hose(s). I suppose we could point one at the existing room exhaust duct (air return), but substantially modifying the duct is probably a no-no.

I've also considered installing a fan box in the door of the room, but I'm concerned that this will only drop the temperature a little. Even right now, with all the equipment on, the room is at 83 degrees with the door open. And the main building A/C turns off daily at 6 PM to conserve energy, so the adjacent room temperature rises at night.

How would you cool this room? Let's say the goal is to bring the temperature with everything running from a steady state of around 90 degrees down to 75 (equivalently, to offset the heat produced by ten 1U servers).

From serverfault John Zwinck

• I would use a portable air conditioning unit that consumed it's own condensation and kept the room at 50% relative humidity. Some people argue that dew point is a better metric, but I haven't looked into it deeply enough and am willing to be corrected. Some A/C units will push their condensation through a hose that snakes through the A/C unit's exhaust hose and thus gets evaporated into the hot, dry output air and into the plenum and exhaust system. You could also get an A/C unit that has condensation tanks and just remember to empty them every day. Annoying, yes. But sometimes an admins gotta do what an admins gotta do.

  Either way, you must have exhaust. You can run a duct hose from the A/C's output into the plenum space or near the outtake. That might not be sufficient though. IMO, A/C output is your biggest problem here. Might be nice in winter, you can barter with different departments on which cubicle space the exhaust hose will run to each week. :)

  Plenty of companies make portable cooling units made for permanent usage in server rooms. Some companies include:

  • Atlas
  • Topaz
  • Movin Cool (I think Atlas bought Movin' Cool, or the other way around, or something else. There seems to be some relationship between the two companies that I haven't determined yet)

  I blogged about portable A/C units a little while back on my old blog here: http://thenonapeptide.blogspot.com/2009/12/list-of-portable-cooling-units.html

  iainlbc : +1 for portable air conditioners, although you should consider pitching a more official server room imo. We used a portable airconditioner in our little wana-be server room at the time, luckily it had a window for AC exaust. 10,000 BTU's was plenty for 5 production (2-6U) Servers. Most units have a small hose and plug somewhere to drain the collected condensation, its important to check this during hot months because if it overflows the radiator/condenser within the unit will start collecting ice, which will ofcourse drastically increase humidity and cause possible leaking.

  John Zwinck : This is the official server room. There's no possibility of moving it. Most of our stuff is elsewhere, but we need a few things within the office area, which this is.
  From Wesley 'Nonapeptide'

• Our server room is about twice as big and has about twice as many servers. Our A/C unit (also humidifier) dies - which is getting to be fairly frequent as it's 20 years old - we open the door between the server room and our adjacent workroom and either put a big fan in the doorway to blow cooler air in or put a portable A/C unit in the room with its exhaust in the adjacent room.

  Neither of those are good long-term solutions, they make me think of this classic article about flawed quick fixes. The best solution would be to hook the server room up to the building's cold air supply, but you commented that you didn't think duct work was possible.

  Other than that, Wesley beat me to suggesting a portable unit, that's probably your only solution, as long as you can duct the exhaust properly.

  From Ward

• You really don't want to be stuffing about with this sort of thing or relying on guesswork. Just for starters I suggest you get that ceiling finished off and fitted with an exhaust fan or two.

  For scaling the A/C I suggest talking to the A/C people, who know a lot more about this stuff than we do. Tell them the load you're currently running, after adding a bit more than than the maximum you can reasonably expect it to ever be. Don't forget to mention that it needs be be running 24/7. I actually prefer to have multiple units, each of which can handle the normal load, even if it's straining to do so. That way you can more easily deal with a failed unit.

  In simple terms, the electricity your gear consumes exits as heat. Work out, or measure if you have the gear, how much you're using. If in doubt get an electrician to measure it for you. It's a small investment that can save you a lot of money later.

  John Zwinck : The ceiling cannot be finished, because among other things there is a 477v transformer hanging from it (putting a drop ceiling in would be difficult because the bottom of the transformer is as low as the ladder racks on the other side of the room). The 10 servers I mentioned use about 350 watts each typically.

  Chris S : A very generic rule of thum, 1 ton of cooling per 750 VAC of UPS (keep your cooling in line with your power capabilities). (1 ton of cooling is approximatly 2500 BTU if you're using portable units). If you plan to add much more in the future, definitely call a consulting place in to size the AC system.

  John Gardeniers : @John Zwinck, if the ceiling cannot be finished it's going to be harder to scale the A/C because the airflow is a much bigger variable. This makes it even more important to get some expert advice - or be very generous in your A/C rating.
  From John Gardeniers

• Youo are going to need 2 AC units. I don't think you'll find something permanent or semipermanent to be cost effective so you are looking at a portable solution. I don't think you should count on using the intake from building air as a vent if they turn it off at 6pm. I'd consider venting it out the door, if you can't cut a hole into an adjacent space. Also remember you are not trying to cool the room, just the intake air on the servers/equiptment, meaning that it's ok for the room temp to be 90s so long as the intake air is in the 70s.

  From Jim B

• I've used one of the portable units in the past, and during peak temperatures, we were able to keep things about 20 degrees cooler. We'd also put some insulation on top of the drop ceilings, which seemed to help quite a bit. On a side note, you're lucky for the lack of windows - this "server room" had an entire wall of windows, which we went to great lengths to block off, as it was a huge source of additional heat.

  From Kara Marfia

• I am looking at this dell standalone http://accessories.us.dell.com/sna/ProductDetail.aspx?sku=A3309556&c=us&l=en&cs=04

  The best part, i think, that suits me is that this unit supports upto 12000 BTU and no holes need to be drilled or anything like that. All this unit requires is a power outlet. Please let me know if you have already used this unit or similar unit and how it worked out for you.

  From Sankar

• Also try to get an AC unit that is network connectable for things like alerting. If it's a unit that consumes it's own condensation in a tank, then the tank may get full.

  Failing that--or perhaps in addition to, for redundancy--get a environment monitor to monitor heat and humidity (ACs can break).

  Sending out an e-mail should be sufficient, but SNMP functionality may also be useful if you want to link in a monitoring system (that also checks your servers, etc.).

  From DAM