Cooling capacity for Server room

[HiriseBuilding]

Most of our clients in high rise building are data call centers and most of them are having a back up A/C units for their server room. What are the necessary data to take when getting the cooling capacity requirements for server room?

 

[Taqwus]

You need to find out the maximum possible heat output from all the devices. I have not seen a code on how to calculate it into ac needed but I have seen a rule of thumb saying that you take the watts item puts out times 3.5 to get the btu needed.
I would also look at humidity controls and if they have firewalls that just dissapate the signals they discard

 

[RossABQ]

"and if if they have firewalls that just dissapate the signals they discard"

Please explain that?

 

[ChrisConley]

It isn't really a rule of thumb, but actually a conversion. The amount of energy that the servers in the space consume (Watts) is the amount of heat that needs to be removed from the space. Watts * 3.41 = Btu/hr

The tricky part is that IT professionals have very little understand of heat generation. Also, high density servers are getting more and more heat per square foot.

Typically, information from the IT people is fuzzy and they don't know what their long term needs are going to be. I've been seeing loads as high as 9kW per rack, with 30 racks in a small space.

APC and Liebert are manufactuer's with some excellent information on server room cooling design.

 

[Taqwus]

A hardware firewall is a device that blocks signals which are basically current flowing over the cable. It lets the signals go through that are on the firewalls access list and blocks the ones that are not on it. I am assuming it just sends the signal to a high resistor to transfer the electricity to heat and disappate it. I know I can hear our firewall's cooling system during periods of high network activity. But honestly, I just spent a few minutes looking around and I could not find out how the rejected signal is discarded and since the energy can not be destroyed I assumed it was turned to heat

 

[KiwiMace]

For a modern server room, the cooling load is equal to the equipment electricity consumption plus the normal building envelope gains.

If you take the IT equipment nameplate power rating, you can usually derate the total by a diversity factor of 0.8. However, careful in larger facilities that are running heavy calcs or using virtualization to consolidate multiple servers into one, as they often run a bit harder. A normal server will draw 70% of the nameplate just sitting there doing nothing.

There are a lot of best practices in the layout and design of services for critical facilities; ref: ASHRAE TC9.9 material, The Uptime Institute, Green Grid for Form, function, reliability and efficiency. If in doubt, call a critical facility professional. syska.com.

 

[RossABQ]

Taqwus, servers are digital. Blocked data isn't dissipated thru resistors like an analog signal, it is blocked. I think someone is pulling your leg.

 

[MintJulep]

Why waste all that power as heat.

Simply configure the firewall to direct the blocked signals' power to an appropriate inverter and use it to run the air conditioning.

 

[ScottyUK]

How do you think the wall gets hot enough to make the fire? It relies on all those Nigerian banking scams and the Viagra and willie extension ads for fuel...

FFS...


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If we learn from our mistakes I'm getting a great education!

 

[waross]

And fuzzy logic is taking over the world. Whatever you do, don't let your fuzzy bunny slippers get near a computer when the firewall is working hard.

Bill
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"Why not the best?"
Jimmy Carter

 

[cswilson]

And make sure you wear your bit mask whenever you are in the server room!

 

[quark]

March 2003 issue of ASHRAE Journal has an article on Data Center Cooling. Further, you can refer to ASHRAE Handbook of HVAC Applications for starting information.

 

[minhice]

The most important with heat load in data center is that :

IT equipments only generate sensible heat (not latent heat).

Normally, cooling load factor for data center is : 1700-3400BTU/h per m2.

Is there any other opinions ?

 

[RossABQ]

You can't use any rules of thumb for heat loads. You have to know what equipment is going in there, and what is likely to go in there in the future. I just did one with blade servers, 25 kW dissipated per (2' x 4') cabinet. The new project is network cabinets that are less than 3 kW and half are inactive at any one time.

You have to press the IT people constantly to understand how their equipment actually operates. They tend to want hugely over-designed systems based on connected load, when in reality there are significant diversities that can be applied.

 

[quark]

0.5 to 1 kW/sq.mtr is OK. The paper I mentioned presents an actual average load of 0.6 kW/sq.mtr (data generated out of 280000 sq.mtr data center floor area). I don't like thumbrules either but we should have some approximation in view of future capacity expansion, particualarly for servers.

 

[KiwiMace]

50 to 100W/sf is typical and can be implemented in a variety of ways provided you use best practice methods.

150W/sf is near the limit for traditional raised floor, downflow floor mounted CRAC units using perf tiles.

Non-Traditional methods (in-row cooling, contained) allow server densities over 1000W/sf.

 

[AbbyNormal]

Throw a load test on the UPS that powers it all

Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[AbbyNormal]

Well when you have the luxury of retrofitting I guess

Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[AbbyNormal]

also consider that IT guys have been burned by bad designs with hot spots , so they like to compensate by having the rooms maintained cold, below 70.

Now for whatever load you calculate, keep in mind that the equipment is typically rated for a warmer entering air condition.

Something that will give you say 40 tons of cooling at 80/67 enetering, may only give you 30 tons of cooling when they want the room 68F.

My experience with big server rooms is to have a very high air flow per ton, it is not like you have much to dehumidify with perhaps the exception of fresh air used to pressurize the space in the summer.

Take the "V" out of HVAC and you are left with a HAC(k) job.