Are my BTU figures for my (small) machine room crazy?

Greetings,
I'm trying to figure out how much cooling capacity we need for our small machine room. The numbers I'm getting seem absurdly high, so I thought I'd run it past the denizens of this newsgroup and see if anyone has any suggestions.
The room is 9 ft. x 17 ft. x 10 ft. high. There's no drop ceiling or raised floor. Two vents from the house A/C discharge into the room, and there's a return vent venting into the drop ceiling in the hallway. It's not a designed machine room per se; it's more of a big closet that we're using to hold our racks.
There are 4 long flourescent bulbs in the room, which I suspect don't add much to the heat load.
We've got two racks of hardware, a couple of small desktops and a CRT monitor. One of the racks is about 2/3 full of various pieces of network hardware -- PoE switches, switches, minihubs, CSU/DSU, and a couple of breadbox PCs that are our firewalls.
The other rack is pretty much full of servers, most of which are 1U servers whose power load is 560W and whose specs claim a BTU rating of 2750 (which seems a bit high, but that's what the specs say).
When we were relying on just the house A/C vents to cool the room, it was always very warm in front of the racks, and downright hot in back of them. When the temperature behind the racks hit 100 deg. F and the HDD temperature monitor I was running on one of the desktops hit 54 deg. C, I decided it was time to do something about the problem. I called Spot Coolers and described the situation, and they suggested a 1.5-ton MovinCool unit, which we agreed to. We ran 12-inch flexible plastic ducting from the cooler to the return vent.
The unit managed to get the temperature in the room (according to its thermometer) down to around 74 degrees, and the temperature behind the racks got down to around 80. Then we turned on a few more servers, and now the room temperature is hovering around 79 and the behind the racks it's up to around 90. I find it hard to believe that the few servers we turned on made that big of a difference, so I suspect that there are other environmental differences going on, although I'm not sure what they could be.
Since we would ideally like to keep the room around 68 degrees, clearly the 1.5-ton unit isn't big enough. The question is, how much capacity do we need?
I took an inventory of all the hardware in the room and recorded from each item's specifications the BTU if given or the wattage * 3.5 (a metric I found in several places on-line) otherwise. When I totaled everything, I got 75,103 BTU, or 6.3 tons. I find it extremely hard to believe that less than two full racks of hardware can generate that much heat, but perhaps I'm hearkening back in the days when most servers only had one CPU :-).
I guess the question I need sanity-checked by the experts here is, can two racks of hardware reasonably generate that much heat? If so, and we want to leave open the possibility of adding a third rack of hardware to the room, it seems to me that we're going to have to get a 10-ton unit. Are there even 10-ton coolers that'll fit in a small machine room?
Thanks for any help and advice you can provide.
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On Wed, 18 Apr 2007 22:12:25 +0000 (UTC), snipped-for-privacy@kamens.brookline.ma.us (Jonathan Kamens) wrote:

As soon as you fill my PayPal account with the appropriate amount of US Dollars I'll be happy to perform any load calculation services or other services you require. Im not a whore but I can be bought. Bubba :-)
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snipped-for-privacy@kamens.brookline.ma.us (Jonathan Kamens) wrote:

Although you've did a fair job of describing your particular situation, there are still far too many unknowns to provide you with the answers you seek.
Is it terribly brilliant to have all of your cooling capacity in one unit, so that when it goes down, even for routine maintenance, your servers go down as well?
Install a 2 - 3 ton ductless mini-split with inverter technology. Most come with low-ambient cooling as standard features.
As load increases, add another ductless mini split. Multiple units with overlapping capacity is far more desirable than one stand-alone.
And yes, Liebert has a 10 ton, 2 compressor model that will easily fit in your room. Of course you will need to locate the remote condensor somewhere else, either roof or side yard.
Do you even have the required additional ampacity in your electrical panel for a 10 ton unit?
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snipped-for-privacy@gonefishin.net writes:

Although you gave a lot of useful information in your response, it doesn't seem like you touched on my most important question, so I've quoted it above (and note that I spelled it out in my Subject line). Let me reiterate... I'm not yet at the point of focusing on figuring out how to cool the room. I'm certainly going to have to do that, but for that I'm probably going to bring in experts. My biggest question at this point is, is it really possible for less than two racks of hardware to produce over 6 tons of heating capacity, or are my calculations totally whacked?

No, probably not, but again, this is not the question I'm most concerned with at this point.

All this sounds lovely, albeit filled with terms I do not recognize or understand, which is why when it comes time to figure out how to actually cool the room properly, I'm probably going to bring in experts.

I'm aware that there are adequate units with remote compressorts that will fit in the room. I am more curious about self-contained units, since it is likely to be difficult to convince our landlord to install a unit with a remote compressor.

If not, then we'll just have to install new circuits.
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Yes
New circuits don't cure the problem of having an inadequite electric panel.
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Most everything over 5 tons is going to be 3 phase
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I doubt he has the capacity for 2 or 3 smaller units.
It a RENTAL!!!!!
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If I were engaged by your landlord, I'd be advising them that you've been adding considerable heatload to his premises and have been using spot coolers with the heat being extracted to the base building air conditioning via the return air and thus compromising conditions for other occupiers. I would also make sure that the additional operating costs including added wear and tear plus any service calls which could be attributable to your compromisation of the thermal comfort of other users all be billed to you. You've got the load (fact), yet you're still farting around getting advice from a bunch of techs who do domestic servicing of HVAC and very little commercial and maybe they've been in a datacentre once or twice in their career (yet still know little about vapour sealing, which you obviosly don't have and sensible heat load which you have bucketloads of). So get on the phone and take your problem to a proper expert who can measure, assess and design a proper solution. In any electronic equipment room in the US I'd have to say the best call would be to get in Liebert who at least understand just how horrible a job you're currently doing and may even take so much pitty on you that they'd actually give proper advice.
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wrote in message

Assuming this is a multi-dwelling rental?
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Jonathan Kamens wrote:

snippy
hanks for any help and advice you can provide.
what you running a porno site?

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Jonathan Kamens wrote:

example, each 1 U server may vary in how much memory is installed, how many discs. To determine your actual load, you need an ammeter; an electrician can help with that. Or get a clamp-on ammeter from Radio Shack, connect it to one 1U server, and then multiply.
As for your steep sudden rise, it may have little to do with adding a few servers; instead it may be due to temp or humidity outside building coincidentally going up, perhaps overtaxing building's AC.
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>>>>>>When I totaled everything, I got 75,103 BTU,.....
Are you running 22,000 Watts worth of equipment?
75,000 BTU/Hour of heat ~= 22,000 Watts of electricity
If not, then you made an error in your calculations.
Mark
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