Server Room sizing

[orc]

Hello all
Hope this is the right forum for this type of question.

How do you determine the heat load of a racked computer in a server room or data center ? I see a lot of people using the manufacturers max wattage numbers for a device but that seems high. For example Dells rack configurator lists the dell poweredge 2950 at min 312 watts\thermal to max 393 watts yet the specs on the servers datasheet show that they are configured with a 750 max watt dual power supplies. Is there a standard forumla that dell and others are using to get 312+ watts from the 750 watt PS ?

Ive read that the best way to get the true thermal ouput of a device is to get a thermal report from ASHRAE but is there an easier way to do it myself without any kind of instrumentaion on the servers themselves ?

Thanks !

[Talz]

Just a thought, but like you said the power supplies don't draw their full wattage. They scale to meet demand just like a transformer would. I guess you could amp-clamp each one and get your wattage that way? Some of the fans are intermittent but it would get you closer than the full rating.

[hvacdoctor]

Let customer give you heat output data btu or watts to size load. You have to size based on manufacturers IT equipment. ABB has some good indfo on line about this.

[JRINJAX]

I agree, use the Equipment's enviromental sheet. If it is not available, use the actual amp draw of the devices.
Be sure and add room load and a factor for new equipment expansion.

[Rickstah]

Server power draw depends really on its utilization and configuration. Typically they will draw a minimum of 40% of nameplate. Which 312W is indeed close to on a 750W power supply.

I typically gauge actual heat load by taking 50-60% of the nameplate values and then calculating into btu/hr. That way you give yourself some wiggle room and don't cut your capacities razor thin leaving room room for expansion.

For instance if I took actual nameplate, I am showing to be at 196% of my cooling capacity. Considering I'm running my CRAC units at an intake temp of 72 degrees, that number is obviously off, but I am running dangerously close at 40-50% calculation.

[orc]

Thanks for all the replies.

Rickstah, the 40-60 % of nameplate does seem to reflect the true wattage of most servers and is inline with the ASHRAE measurements that Ive seen.
Dell and IBM both have rack config tools and use the 40-60% values to show max power used. The building management people are under the assumption that we are over capacity based on looking at the maxx wattage\nameplate values but I would like to prove that we should be sizing the room based on 40-60% numbers. Any recommendations on a cheap but reliable amp-clamp ?

[Rickstah]

Thanks for all the replies.

Rickstah, the 40-60 % of nameplate does seem to reflect the true wattage of most servers and is inline with the ASHRAE measurements that Ive seen.
Dell and IBM both have rack config tools and use the 40-60% values to show max power used. The building management people are under the assumption that we are over capacity based on looking at the maxx wattage\nameplate values but I would like to prove that we should be sizing the room based on 40-60% numbers. Any recommendations on a cheap but reliable amp-clamp ?


I would recommend the Megger MMC850, http://megger.com/us/products/ProductDetails.php?ID=656&Description=clamp

It is a multi/single core clamp meter, so you can clamp the power cords and get a reading. No need to go digging in the breaker panel and risk opening circuits or getting zapped.

[Randy S.]

In a single unit room, I would suggest the actual KW come in at no more than 70% of the sensible capacity. That works for this area, but I'm not in humidity country.

[chillrdude]

I really think that to get a good grip on what you are trying to do, you should read this

http://www.hvac-talk.com/vbb/showthread.php?t=64645&highlight=server+room

:D

[orc]

Rick , thanks for the tip on the meggar


Chillr, wow, that looks like the thread im looking for ! but 97 pages wtf lol, it will take a while

[chillrdude]

That was the thread from hell, it just kept going with no end. It was terrible.

[JRINJAX]

We have had very good success on server rooms using Mitsubishi Inverter drive units. Our fabrication department mounts a wall mounted condensate overflow pan and the inverter matches the load an allows for expansion of the equipment load.

[MRcoolingMAGIC]

Hello all
Hope this is the right forum for this type of question.

How do you determine the heat load of a racked computer in a server room or data center ? I see a lot of people using the manufacturers max wattage numbers for a device but that seems high. For example Dells rack configurator lists the dell poweredge 2950 at min 312 watts\thermal to max 393 watts yet the specs on the servers datasheet show that they are configured with a 750 max watt dual power supplies. Is there a standard forumla that dell and others are using to get 312+ watts from the 750 watt PS ?

Ive read that the best way to get the true thermal ouput of a device is to get a thermal report from ASHRAE but is there an easier way to do it myself without any kind of instrumentaion on the servers themselves ?

Thanks !



0.400 watts per sq./m and you will never gonna go wrong.don't forget to supply a fresh air from the local duct unit.:D