So am I on to somthing... or am I just jerking off....

[gpwasr10]

So I started my new job as a building Engineer a couple weeks ago. It's been good, but busy. We have three large companies in the building and they all have their own facilities guys. All seem pretty friendly and are good guys. I noticed on my computer though that two of their server rooms run extremely hot. Like 86 degrees hot in one case. I am reading a delta-t of like 6 degrees (chilled water system) across th coil. Now granted this unit is at the end of a looooong run, but still, not right. I went and checked it out finding two small unit coolers in the room in a feeble attempt to keep the temp low, has two 8" hoses that blow cool air onto the units and the discharge is piped into the ceiling right next to AHU’s return in the ceiling.

Checking the AHU out I found the re-circ pump was shot, so I replaced er with a new one. Problem solved right? Well kinda. I am now getting a delta-t of 14.6 with 80.7 RAT and 66.1 DAT. Now both of those small unit coolers are still running and still blowing their discharge into the ceiling right by my AHU. So I told them that the room would likely continue to run hot until they shut those small units down as they are undoubtedly adding more BTU’s in the room then they are removing and are becoming an additional load on the already over taxed AHU’s coil. They are not convinced but agreed to try it out on Monday when I can observe the room for the day.

I have no idea on what this units history is, and the computer only tracks Trend logs for about a week or so, so there is no telling how long the re-circ pump has been out. And there is no way of knowing if they added those small unit coolers before or after the pump went out. But since the fire wall for the server room goes all the way to the ceiling the only place for the heat from the unit coolers to go is into the ceiling/plenum and get removed by the AHU’s coil.

[markwolf]

I am not convinced either.It is common for server's to be enlarged with no thought at all given to how much heat load the extra equipment will add to the space.Using the return air to take away extra heat from spot coolers happens alot IMO.I would bet you see the temps in that room skyrocket when the coolers go down.I would not be sitting looking at the computer but right in the room to turn them back on.with an 86 degree ambient I cannot believe they do not have server crashes as it is.It is time for a liebert mini split or self contained unit for the server room!It sounds like you have room in the cieling & an available chilled water source.Call an outside contractor & get some pricing.I would not want to be the new guy walking into a possible nightmare without knowing weather or not they will have the funds or willingness to part with them.I hope you don't step on toes or get caught up in politics!good luck!

[tex~n~oz]

gpwasr10,

Just a word of warning.. You are right on all accounts and observations.

They ARE adding heatload to the room AND you will definitely piss someone off when you step on their toes.

Sounds to me like a critically sized AHU for that room and by adding the heat from the other 2 units has sent it over. You will increase cooling by the sum of the entropy of the 2 units. I dunno.. maybe 20% of their rated BTU?

Now back to the "pissin someone off" thing...

All this time they were gettin a pat on the head for a "job well done" and then the "new guy" strolls in and slaps the bosses %*&$ right outta their mouths...

In time you will become sarcastic, and just generally not liked with your "je m'en fous" attitude until a problem has them by the balls and they NEED you to help em out. They will hate you again when it's over because you've driven another nail in their foreheads even though it was at their own request.

One word of advice.. Make sure it wasn't the BOSS who had those units installed or you'll be packin-up and headin home just about as quick as you got there.

Get used to eating lunch alone. ;)

[gpwasr10]

gpwasr10,

Just a word of warning.. You are right on all accounts and observations.

They ARE adding heatload to the room AND you will definitely piss someone off when you step on their toes.

Sounds to me like a critically sized AHU for that room and by adding the heat from the other 2 units has sent it over. You will increase cooling by the sum of the entropy of the 2 units. I dunno.. maybe 20% of their rated BTU?

Now back to the "pissin someone off" thing...

All this time they were gettin a pat on the head for a "job well done" and then the "new guy" strolls in and slaps the bosses %*&$ right outta their mouths...

In time you will become sarcastic, and just generally not liked with your "je m'en fous" attitude until a problem has them by the balls and they NEED you to help em out. They will hate you again when it's over because you've driven another nail in their foreheads even though it was at their own request.

One word of advice.. Make sure it wasn't the BOSS who had those units installed or you'll be packin-up and headin home just about as quick as you got there.

Get used to eating lunch alone. ;)
The room is down to about 79-80 Deg right now. And in a month all those servers are going into a dedicated server room. One of the first things I did was popped out some cieling tiles right behind and above the units so the heat can escape a little easier. The way it was, they had only two returns in the far corners of the room.

The good news is that none of the "old guard" work thier anymore. This building was just bought by a new company and it is just me and another guy that I have known for years.

I do not think that shuttin those two spot coolers will bring the temp down to 65 deg or anything, I just think that if you are removing 10 BTU's but discharging 15 by doing so then your trying to **** upside down. They mentioned that at night they can shut a few servers off without problem. I am going to suggest that they do so over night to let the unit play catch up then we shut the spot coolers down. With a lower RAT my SAT will improve and the unit can perform its job.

[Freezeking2000]

Just duct the exhaust from the portable units thru the wall as a back-up!

[secorp]

If not duct:
At the very least, cut a whole in the fire wall and put a fire damper in it.

[gpwasr10]

If not duct:
At the very least, cut a whole in the fire wall and put a fire damper in it.

Freezeking, Secorp,I have already mentioned that but they seem to be worried about cutting a hole in a fire rated wall, even though the building uses a sprinkler system... I guess we will find out monday the plan so I will let you guys know then. Of course I was told that my units 65 DAT was unnacceptable... even though I explained that you can only cool the air so much and since that RAT is 80+ deg that that was as good as it was gunna get. But **** man... wtf do I know about HVAC of all things....

[onetime]

Standard A/C units condenser puts out 25% more heat than absorbed in the evap. (heat of compression). I usually find that taking out ceiling tiles adds to the problem as you are now letting some of your cooled air out and bringing in warmer air. Cutting in the exhaust holes is not the answer either, make-up air has to come from somewhere and its usually warm air, but it may be better. If you got the temp. down 6F maybe they should wait for a month and do it right in the new room.

[whec720]

gpwasr10,

I wouldn't mess with climate integrity, popping ceiling tiles and such. There are other things you can do to improve the situation. Check out this white paper from APC. This my help you: www.apcmedia.com/saletools/TDOY-5U362W_R2_EN.pdf.

[whec720]

Try this for more luck: www.apc.com/go/promo/whitepapers/index.cfm?tsk=s897y

[gpwasr10]

I normally pop the tiles out right above the racks of computer server racks and move the supplies further away from those openings. This has the effect of the cool supply air falling to the floor on one side of the room (sometimes two) while the hotter air for the equipment naturally rises out of the room, the low pressure right there above the units as an escape only serves to hasten the process.

This has always worked for me. Seems to be working here as well. Hot room is now down to 78 degrees and the second hottest room is down to 74 degrees. That’s with the hot condenser air still blowing hot into the return.

Onetime: It looks like the new room will be top notch. Leibert units all the way around and raised floors.

[propmanage]

You should not exhaust any place but out side. Your No-Good exhaust mixed air temperature must be bringing your load up to a point the unit is unable to deliver. How is it cooled? Chilled water? If they are planning on moving and no one is pushing you to do anything about it, just ask if this is something you should be spending your time on. The responds will probably be " leave it alone” They probably have been short handed and reacting with out a budget to upgrade.
Keep the filter clean and pick up another project if they wish to leave good enough alone. Unfortunately that is the way things go with commercial work. Nothing is cheep nothing is permanent and no one can make a decision. It could have been this way for years and the first right thing you do; one of the servers will crash. Best thing is to let some one that matters know you are alert and noticed and then let them provide you with direction.

Spinning your wheels on a dozen projects and one out of a dozen evolves, as that one takes off another dozen pop up and so on and so on. After a while you will see there is a madness to the method but no one will ever tell you or talk to you about it and if and when you understand you will be ready for advancement.

Good luck