cooling systems

Joel Jaeggli joelja at
Fri Apr 11 18:19:15 EDT 2003

In our system a 24 ton chiller has a backup water source in the form of a
city water supply... There's no return on that one, it gets dumped into
the waste water treatment stream so your water bill goes up in a big
hurry, and it's way less effective because the water is in the upper 50s
instead of the mid 30's. It's controlled by a vacuum break valve so 
switchover is automatic if one supply goes away...

Backup fans, extensive temperature monitoring, and thermal kill switches 
are still necessary, esp as there have been about 6 chiller failures since 
I arrived in 93 (the thing is 22 years old at this point). water under the 
floor is always one of those exciting alarms...


On Fri, 11 Apr 2003, Mark Hahn wrote:

> as usual, Robert (et al) gave a comprehensive answer.
> I'd like to just emphasize one thing: expect trouble if you
> use chilled-water cooling that's designed/managed for offices.
> ours works fairly well during the summer (16 tons of chillers and
> 35 KW dissipated, which should work out to 10/16 utilization.)
> but facilities people tend not to think of chilled water as a 
> critical resource, and construction people certainly do not.
> you *will* have problems with the temperature of your chilled 
> water (not to mention whether it's even flowing).  I was surprised
> how little thermal capacity the chillers/pipes have - our room
> heats up in seconds if there's any disruption.
> and don't forget to run your chiller blowers on your UPS :(
> I expect we'll be adding supplemental electical cooling soon ;(
> consider wiring up a few ibutton thermo sensors - I have 5 now
> (incoming chilled water pipe, chilled air duct, dead/ambient
> and hot/return air), and log them every 30 seconds or so.
> yes, I have a little script that monitors the temps, logs them 
> in mysql, pages me, powers off.
> clusters are getting bigger, and these problems aren't going away.
> yes, one solution is to use laptop processors.  that works, but is 
> simply inapropriate for some applications.  another is to try
> water-cooling, which I've heard some cluster vendors are working on.
> the main appeal there is to avoid flakey CPU fans, and potentially
> to exchange and transport heat more effectively.  but you're still
> probably dependent on a chiller somewhere.
> regards, mark hahn.
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Joel Jaeggli	      Academic User Services   joelja at    
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