Network Closet Cooling

Unanswered Question
Jun 19th, 2008

Hey guys,

I'm looking for a little input from those with experience with network closet cooling.

We are going to have two classes of IDF's in a new building we're putting up. The first floor closets are going to have two Cisco 3560-48TS switches, one Cisco 3750G-12S Fiber Switch, a 500VA UPS and a small Netgear PoE switch. The second floor and up closets are going to have the same equipment without the fiber switch.

These rooms are also classed as electrical closets since there are breaker panels inside them and so the local fire code does not permit us to have any ventilation devices as the room must be weather sealed.

The contractors responbile for the construction project never installed AC to the closets as requested and are now refusing to do so. Their engineers state that their "opinion" is that in a sealed envrionment with no cooling or ventilation that this equipment will be able to sustain operating temperature around 80-90 degrees.

Given that these closets should be dissipating between 1100 and 1500 BTU's/hr depending on the configuration, we have serious doubts regarding the environment for our equipment.

Does anybody have any experience with a similar setup without any cooling or venting systems?

Any help is appreciated :)

I have this problem too.
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hennigan Thu, 06/19/2008 - 12:19

This is dependent on your local fire and building codes, but in similar situations it has been acceptable to install a "fire damper" in the HVAC ductwork. This is a spring-loaded shutter with a low-melting-point metal link holding the shutter open. In the event of a fire, the link melts and the shutter seals the duct. More sophisticated versions integrating to a fire alarm, etc. are available.

An alternative is a two-part split system A/C just for that room. You have an indoor unit with just the evaporator coil and a fan. Freon lines extend to a rooftop or outdoor compressor and condenser. No external ventilation or make-up air, and the only penetrations are for the freon lines and a small condensate drain.

"Storage" closets on architectural plans often get turned into server/network closets. This usually results in cooling issues. :-(

james.kazin Thu, 06/19/2008 - 12:56

Hey thanks for the reply!

The construction company tells us at this stage that it's going to cost well over $300k so running AC lines or even an exhaust line for a portable AC is off the table.

Right now we're mostly worried about if this is feasible no ventilation at all.

Collin Clark Thu, 06/19/2008 - 13:11

Like Jay stated much of this depends on code, but I have used these devices and they work quite well. They either need a drain, or like a dehumidifier, they have a local reservoir which you need to empty. I was told by APC they can vent directly into the ceiling space.

Manual for APC Cooler:

hennigan Thu, 06/19/2008 - 14:03

The APC portable unit described in another reply requires an exhaust vent which would violate your fire code.

If the UPS is 500va, that's the maximum you'll consume with the proposed gear. Plug in five, 100-watt light bulbs, hang a thermometer on the wall and close the door. Wait a day and read the thermometer. That will give you an idea as far as today's load goes.

However, in the future that space will be forevermore known as the "network room" and additional switches, routers, Muxes, PBX gear, etc. will flourish and multiply until the whole thing melts down.

Design it right now, or suffer later.

$300K for a split-system A/C installed is not just unreasonable, but absolutely preposterous.

james.kazin Thu, 06/19/2008 - 15:00

Yes, 300k+ is absolutely ludicrous.

We floated the portable AC idea with their engineers, mostly to see what they could do about exhaust ventilation and they said that it's also off the table.

Fortunately all of our really expensive gear like our 7200 series router and servers will be in the MDF which they actually plumbed some AC into.

Tomorrow I'm going to shut down the AC in a similar IDF with two 3560 switches and keep an eye on the temperature.

Believe it or not one of these engineers fighting so vehemently for a hot network closet had the nerve to send out a group email saying that our equipment load had less heat dissipation than 3 40W light bulbs. Given the attitude coming from this entire company on the topic, we're pretty sure that someone screwed up and now they're just trying to cover themselves.

We're basically stuck here and it's a pretty crappy situation.

dbroder Thu, 06/26/2008 - 09:52

James, I think you're right about 'somebody screwing up' here... I had the same problem a while back.

The 'engineers' who designed our new building (a scant 10 years ago) informed us that our server room would not require cooling (WTF?!?!) -- the 'air flow' through the room would sufficiently cool the room (400 sq.ft 8'x25').

We had about 30 servers at the time (various shapes/sizes). My calculations (rough as they were) showed that we'd have overheating problems within a couple hours.

They would not budge -- everyone 'higher up' took their word for it and IT Services here were ignored... until the weekend we moved our equipment in.

I had three of our VPs and two of the 'engineers' we hired come by the evening of our server room move. I asked about the air flow and how they came up with their high-priced opinions.

Since I'm not brain-dead, I secretly rented a portable A/C unit and had it at the ready after my show-and-tell session.

We had a 5 ton A/C unit installed the following month -- on the engineering company's dime.

In regards to your scenario, I think you'll have to re-provision some separate space for yourself in order to satisfy both parties. There doesn't seem to be a way to keep everyone happy over there.

Good luck.



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