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#70391 - 10/06/06 06:58 PM Computer control room a/c ?  
sparkync  Offline
Joined: Oct 2002
Posts: 828
Does anyone know approx. what size and type air condition it would take to efficiently cool a 20ft. X 15 ft. room full of computer equipment, and telephone equipment? Does a room like this need have the humidity controlled? I would think so. I have a potential customer who is leaving it up to me to decide the amount of a/c and type of a/c to put into a future room where all his controlling "server" equipment etc. is going to be located. He has an outside wall, and says that where their existing equipment is, has a window unit of some kind. He said he did see some sort of tube that might have something to do with the humidity control. Any suggestions will be appreciated. Thanks Steve...
Almost forgot, the ceiling will probably be around 10ft. high. Thanks again.

[This message has been edited by sparkync (edited 10-06-2006).]

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#70392 - 10/06/06 07:46 PM Re: Computer control room a/c ?  
LarryC  Offline
Joined: Jul 2004
Posts: 783
Winchester, NH, US
You need to break this up into several parts.

Heat gain from the machines, heat gain from the building, heat gain or loss from the outside, and heat gain from people. Heat gain or loss from the air handling equipment if present. What are the required temperatures for the equipment? What are the allowable temperature fluctuations, and maximum rate of change of temperature?

What are the humidity requirements of the equipment? Do you have any external sources of humidity? Do you have any internal sources of humidity?

As far as systems go, there are water cooled package units, there are split systems with the evaporator and fan inside the room and the compressor and condensor outside on a pad. There are window units and thru the wall units. There cooling cools that tap off of the building chilled water loop.

How are you going to get rid of any condensate from the chiller coil?

From a liability point of view, what happens if you are wrong? Does this equipment need UPS's and are they in the conditioned space?

If you are not comfortable answering all these questions and more, I don't think that the HVAC design should be your responsibility.

Larry C

#70393 - 10/06/06 07:54 PM Re: Computer control room a/c ?  
hbiss  Offline
Joined: Dec 2003
Posts: 886
Hawthorne, NY USA
I have a potential customer who is leaving it up to me to decide the amount of a/c and type of a/c to put into a future room where all his controlling "server" equipment etc. is going to be located.

If you posted that comment over at the HVAC forum you would be able to hear them laugh all the way over here! Pretty much what we do when we look at their electrical work.

Computer room environmental control is a specialized field, even being an HVAC guy doesn't mean you are qualified. If I were you I would act as a consultant on this. Hook your customer up with a company like Liebert, charge for your time and tack on a percentage. You will come out ahead, believe me.


#70394 - 10/06/06 08:14 PM Re: Computer control room a/c ?  
sparkync  Offline
Joined: Oct 2002
Posts: 828
Case closed. Sometimes it's hard out here trying to make a buck [Linked Image] I'll ship it out to the a/c guys. By the way, the HVAC guys forum I used to go to must be shut down.
The customer who is getting me to look at this job, seems to be as "ignorant" ( I say that respectfully) as I am about this a/c system that is needed. He takes me through a several thousand sq. ft. building, casually tells me what they may have, but not quiet sure; tells me he wants generator back up for the computer room, etc. etc., The job is suppose to be through by 11/18/06, but he still hasn't started demolition on old part, has no prints to go by, and is just wanting a price on this project. He is either using me to do the work he is suppose to do, or it's the biggest commercial job I'm getting ready to make a profit on [Linked Image] because my price is going to have to have a lot of "cushion room [Linked Image] Thanks for the input... The truth is what I wanted... Steve...

#70395 - 10/07/06 01:25 AM Re: Computer control room a/c ?  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,121
I did a bit of this. What is the nameplate of all the installed equipment?. Basically you compute 3400 BTU per KW of sensible heat. Then you add a few hundred BTU for each person as latent heat. It really gets a bit more complicated but we don't have enough info to answer the question. Probably the least important is the size of the room if this is already in conditioned space.
I can dig up the real template if you want to run the numbers but I would start with electrical load at 3400 BTU per kw and that will get you close. You don't really have people hustling around a server room screwing up your humidity like we had in a computer room.

You still will need humidification if you are up north. I tend to forget that down here in the swamp. Shoot for at least 50% to avoid static shocks to the equipment.

[This message has been edited by gfretwell (edited 10-07-2006).]

Greg Fretwell

#70396 - 10/10/06 02:49 AM Re: Computer control room a/c ?  
Scott35  Offline

Broom Pusher and
Joined: Oct 2000
Posts: 2,708
Anaheim, CA. USA

tells me he wants generator back up for the computer room, etc. etc., The job is suppose to be through by 11/18/06, but he still hasn't started demolition on old part, has no prints to go by

One of the Design / Build Projects I am currently doing Plans for, is a New Standby Genny for the Customer's Network Equipment Room.
One Existing Panelboard, fedfrom an existing 150 Amp Feeder; existing dedicated HVAC equipment on same Panelboard - as are the Servers (Rack Mounted Equipment).

I also "Became Elected" to draw the Architectural + Structural (Concrete) details, along with the Electrical Plan pages of the complete set.

Submitted Plans to Building Department originally in the last week of August.

Since I are eeelecktrikal injunear, never really had to go through the steps which Architects do - until now!!!

Planning Division: Screening, exact locations, etc. - all a nice new lesson for me, and thankfully did not get the Planning Division examiner irritated with me!
11 working days later (and a revised planset), got the "Okee-Dokee" approval stamp from the Planning Division.

Now to submit the Planset to Building!

Needed Plansets for:
* Building,
* Electrical,
* Police Department,
* Fire Department.

Submitted what I had, and waited for the Plancheck Corrections list.

* Building (outsourced plans examination): All very basic, except concrete and seismic calculations. These are being done by a P.E. and will bear this person's stamp.

* Electrical: No revisions necessary (very nice report from the in-house examiner!).

* Police Department: Not required for this project (not close enough to bother Residential'ers).

* Fire Department: 3 pages of Fire Department required corrections!
This ends up to be at least 2 separate pages in the planset.

I received the plancheck corrections beginning of last week, and expect to have a master vellum set ready for blackline copy by Monday of next week (10-16-2006).
Originally, the Planset was 4 pages - now it will be 7 pages. Fortunately, some of these things may be billed as an extra!

So what I am getting at is your client's "Dream Date" of an 11/18/2006 completion, could easilly become a "Reality Date" of something like 03/30/2007!!!

I never knew so much stuff was required for Planchecking of a "Seemingly Simple Item" (the Generator).
Then again, I never took on all the related submittals - only our portion, the Electrical! (just submit our design consepts on several blackline copies, Architect takes on the majority of Plancheck submittals, I deal with Electrical Plancheck).


p.s. As already mentioned + done, you are better off letting someone with I.T. Room cooling experience take on this task!

Not sure if very many people reading this post have been in Server / I.T. Rooms (NERs), but in a nutshell, Ice Cream melts Wayyyyy Slooowwwllly in these rooms!!!
(you can keep your Lunch fresh and Sodas cool in these rooms!)

Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

#70397 - 10/10/06 12:36 PM Re: Computer control room a/c ?  
SteveFehr  Offline
Joined: Mar 2005
Posts: 1,213
Chesapeake, VA
You can't design the HVAC for a server room based on size, you need to know the actual load. One thing about servers that makes this easy is that the electrical kW in is pretty much exactly the heat kW out. So, if you have a good idea what the electrical load is going to be, every 3.8kW (12,000 BTUs) is 1 ton of cooling. Plus extra depending on climate, people in the room, etc, but unless you're installing this in a tin shack in Africa, the cooling load will be absolutely dominated by the equipment itself. Based on experience you're looking at probably somewhere around 4-8 tons of cooling for that space, but you really do need to calculate it, and don't forget that also need to distribute it! You can do some estimates, but this is definately one for the HVAC folks to tackle when it comes down to it.

BTW, UL labels are wildly inaccurate. Clamp the equipment to get realistic numbers if you can, or else you'll end up WAY overdesigning your electrical and HVAC.

Humidity is rarely an issue in server rooms, just make sure you're taking condensation into account. For one, try not to route supply ducts over equipment- no matter how well they're lagged, they LOVE to drop condensation.

- And don't forget to plan room on your generator for the AC!

[This message has been edited by SteveFehr (edited 10-10-2006).]

#70398 - 10/10/06 01:47 PM Re: Computer control room a/c ?  
George  Offline
Joined: Feb 2002
Posts: 375
You really need to know what is going into the room.

1000watts/sqft is achievable.

1000watts total is more typical.

If the client is simply moving his existing room room of equipment to this room, his existing A/C should be close to the proper size.

#70399 - 10/10/06 02:06 PM Re: Computer control room a/c ?  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,121
If your computer room is that cold you are not following the manufacturer's recomendation. The spec is 75 degrees at 50% RH. In a well maintained computer room the Weksler will draw two perfect circles at that spec. I have seen them wear a hole in the chart and the outer "ring" stops turning.

Greg Fretwell

Member Spotlight
Levittown, PA
Posts: 810
Joined: April 2004
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