Server room heat load problem.

[hollandhvac]

I have a server room of 100 m2 (1076 ft2).

The intention of IT is to install here servers with a total equipment load of 450 kW (1535464 Btu/hr). If I start to select Ac units for this room I can go for 4 units (3 duty/ 1 standby), but they take about 26,25 m2 of space , or if I take ( 2 duty/ 1 standby ) it takes 22,5 meters of space. This includes the maintenance area.

Looking at the left over room load I will get 450/ 75 = 6 kW/ meter2.

As this is a new building I am talking about, it is my opinion that this room is too small.

I have to admit I did not get a lay-out drawing that indicated where the servers should go.

But what is your opinion?

 

[KiwiMace]

I think you will need to consider containment and high density cooling solutions. This is going to exceed any practical raised floor implementation. Space saving solutions usually involve moving the air handlers out of the room and ducting overhead supply to cold aisles, and returning out of the hot. You will need lots of height for this. Filtration is important here.

In-row cooling will manage this, but you will lose rack spaces.

Check out which options may work for you, rough out the plans and advise your client what they can realistically get in the room. IT folk are notoriously optimistic, as the don't understand the limitations of the cooling.

Coordinate with structural and electrical too: floor needs to carry all this weight, and electrical may have been planning whips underfloor. You probably don't need a RF here.

 

[ChrisConley]

I'd check into some solutions from Liebert for high density rack cooling. I've used their systems on a few projects with success.

It sounds like you're short on space (typical) and some of the XD cooling solutions from Liebert might help you out.

 

[sspeare]

You say you are selecting AC units. I assume by "AC Unit" you mean off-the shelf DX cooling equipment, perhaps an indoor coil/air handler that is matched to an air-cooled condensing unit? If that's the type of equipment you're condidering, make sure you select equipment that has a Sensible Cooling Capacity (SCC) that is greater than your heat gain. If you select the DX equipment based on it's Total Cooling Capacity (TCC) - like you would for a comfort application - you'll be in trouble. That's because the Sensible Cooling SCC will typically be only 70 to 75% of the TCC. The heat gain of your Server Room is probably 100% Sensible Gain from electrical use - there is no latent gain from people, cooking, process equipment, etc. So if you select equipment based on Total Cooling Capacity (TCC) you will only get 70-75% of what you expect. Ignore the rating data for Total Cooling Capacity, and make sure what you select has a Sensible Cooling Capacity that exceeds your heat gain.

 

[walkes]

We recently completed a system where there is chilled water provided to the rack system where the heat is exhausted through a coil on the rack enclosure and discharges the air at 72°F or so to the space.

The Liebert unit in the space maintains humidity control and an ambient temperature of 72°F in the space.

The heat from the rack isn't seen within the room.

 

[hollandhvac]

Kiwimace, I will be thinking of solutions like this, but I have space to put an air handling Unit. Only in the room it self, I may use an adjacent room for one unit but the other 2 would have to remain in the room.

Chris, we have liebert units now and will look into those.

Sspeare, Indeed the complete equipment load is only sensible, there are no people in the room. There has been a debate before about TCC=SCC in earlier topics where some would state that TCC could be fully SCC if no latent load was available. I would like to know your source or experience.

Walkes, have you got a source or a model of liebert unit that I could have a look at for this system?

 

[KiwiMace]

What are the range of rack loads? Say about 65 racks in this space - 6-10kW a rack is manageable without containment with good design (from everyone). However, back to the rack loads question, if you have a room full of fibre patch and a block of 20 online transaction machines running 15-20kW then you need to up your game.

Secondly the level of redundancy, you indicate N+1 above - Tier 1 or 2. This is critical to your clients satisfaction level and intertwined closely with floor area. Something to discuss clearly; average hours of expected annual downtime is usually a well enough understood currency.

Re: Sensible heat capacity - is the only number to look at on the units.

Manufacturers of HD cooling - Liebert and APC are obvious - Rittal is a brand that is impressing in the US market, supposedly coming from Europe. Vette makes doors - early benchmarking found them a bit erratic in control but performance/efficiency was good.

 

[walkes]

The SGI system uses a water-chilled door, more info:

http://www.sgi.com/company_info/newsroom/media_coverage/downloads/hpcwire_datacenterchill.pdf

The Liebert unit is a standard DS unit with an upflow configuration used to maintain humidity levels in the room.

 

[Waramanga]

I beleive that APC have chilled water 'in-row' coolers available. I am not sure if they do humidification as well, you may need a couple of Ordinary CRACs to do that for you.