Do I Need a Fan or Supplemental AC in my IT Closet?

MeltingOne area of design I find consistently overlooked is the small IT closet. In the last month, I’ve seen a few 5,000 sq ft pre-built offices or spec spaces where the landlord provides a very small IT closet. But look up in the IT closet ceiling and there may be no sign of mechanical cooling equipment or even an exhaust fan.

The reason I regularly hear from landlords for this oversight is that because it’s a small room, there’s not that much equipment or heat to be generated. Therefore, there’s no need for conditioning.

Hear this, just because the closet is small doesn’t mean it doesn’t generate heat that could potentially be harmful to your equipment.

Now if you’re a tenant thinking of moving in, you’re probably visualizing your current IT closet that’s overheating and tried the following remedies:
1. Leaving the door open
2. Brought in portable cooling
3. Exhausting the hot air into the plenum
4. Louver the door
5. A number of other methods to keep your equipment from shutting down.

So what do you do in the new space?

When you’re dealing with spec space, your options are limited because the mechanical design has already been completed.  You’re left with figuring out how to drop in a Mr. Slim Unit and where to place the condenser; or adding an exhaust fan which is marginally helpful; dumping building air into the closet – but what happens when it shuts off at 6pm?

According to Morais Miranda, RCDD, president of New York based Technology Solutions Design Group, he advises if your power consumption is at least 5kVa, the minimum needs for an IT closet is a 1.5 ton unit minimum. That’s not a lot of gear in the rack to generate that kind of output.

Here’s the basic formula to calculate your needs:
Watts = Amps x Volts
1 Amp @120 Volts = 120 Watts
1 Watt of Power = 3.412 BTU
3.412 BTU x Watts = X BTU
1 ton of cooling is 12,000 BTU/hour, not counting people load

So to calculate a 5kVA = 1.5 Ton AC unit:
5000 x 3.412 = 17060 BTUs/12,000 BTU = 1.42 Ton

If you can’t do A/C in the new space, then you should at minimum louver the door, dump building air plus add an exhaust on a thermostat.

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9 Comments on Do I Need a Fan or Supplemental AC in my IT Closet?

  1. We are just building in an offices TI an IT room and are solving the HVAC with 2 – 1.5 Tons InRow units to operate 24/7 and backed up with a generator. Units system is new for me, they take the heat to the plenum and are mounted at side of racks.
    The units are produce by American Power Conversion.

  2. Richard Millrr // October 24, 2013 at 10:50 pm // Reply

    Put a supplementary A/C unit in the closet and minimize your risk factor.

  3. Mission Critical?
    Perhaps this is overkill, but some of my clients have wanted to keep the equipment operating and cool even when the central air conditioning is down. In that case we have simply located a thru-wall window A/C unit above the IT closet door, and pumped the excess heat to the corridor or corridor ceiling.

    We have also on a few occasions supplied that A/C unit with backup generator power. If your VOIP or phone system lives in that room (as it typically will), you should seriously consider supporting its operation even when the central A/C is down.

  4. Fantastic article
    !

  5. Excellent, well researched and thoughtful article, particularly the forumulas. Thank you. This info needs to carry through to the architects, so they can pass it through on plans! Codes vary as to municipality and sometimes you can/can’t have louvered doors, for one example. Pushing solution off on tenants is poor end-strategy, for long term relations as well.

  6. Tim Kendrick // October 18, 2013 at 3:45 pm // Reply

    So very true… I have done many T.I. projects where the IT equipment is in a cabinet… No ventilation whatsoever… I always suggest to the tenant to move this equipment into a ventilated storage room with a dedicated space… In other words, make sure they don’t pile boxes or other items that would block the equipment and restrict air flow… Good article…

  7. Note by Ron Dickson–

    When you consider the critical importance of the IT gear, it would be foolish to trust its safety to a single exhaust fan. It would be better to install a second fan on a dedicated electrical circuit and with its own thermostat. If the primary fan fails, the back-up fan should come on automatically. This should also turn on a warning light at the receptionist’s desk or other highly visible place.

  8. susan curtis // October 17, 2013 at 1:32 pm // Reply

    Great article and so very true!!!

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