Cooling the room when the UPS is on but the CRAC is off

[BillP]

Last weekend, I discovered my computer room air conditioner is not on UPS. I guess the engineer said it couldn't be, but it's not on the building generator either! Before I get pages on my blackberry from the Netbotz Central this weekend and race in from 2 hours away in Charlestown to prop open some doors and get fans running. ( I can't shut the data center down )

Does anyone know how long the computer room can run with the doors open and fans running before it gets overheated?

[BillP]

I found it and attached it. This is the file you were talking about "Transient Heating" .xls There's also another one I made from an APC white paper "Cooling and Power worksheet" .xls which you might find useful.

[BillP]

One of the challenges of cooling, as you point out Mr Tuff, is what to do when the lights go out. Uninterruptible power is easy to do, and keeps the servers humming along when utility let's you down. Unfortunately that also keeps the heat coming. Therefore you really need uninterruptible cooling as well.
You can place CRAC units on the gen set, if you have one, but depending on the length of time it takes to get the back up generators running and the a/c started up again, it could be a few to several minutes. In that time span you can have quite a bit of localized recirculation and over heating. In very high density applications, servers can bake in as little as 15-20 seconds when you have a total loss of cooling. Pretty scary indeed!
I have recently done a design, a retrofit of an existing IT space, where the client's needs dictated the need for uninterruptible cooling. I used some InRow RC units, which are chilled water only and can run off a UPS. They have no compressors, so there are no high in-rush currents, which can force UPSs into bypass. Then I added new pumps for the CW loop that were VFD driven. The VFD gives them a soft start, so that can go on the UPS too. The mains were already 6" so I didn't make them any bigger, but I did upgrade the chilled water storage tanks so they were larger, this is just like adding more batteries to the UPS. So now, when the power goes out for this customer, the UPS keeps the pumps circulating the cold water in the pipes, and thru the RC units in the data center. The RC fans keep moving the air thru the space, and now the client has uninterruptible cooling with a calculable run-time for cooling. How awesome am I??

[BillP · Accepted solution]

Last weekend, I discovered my computer room air conditioner is not on UPS. I guess the engineer said it couldn't be, but it's not on the building generator either! Before I get pages on my blackberry from the Netbotz Central this weekend and race in from 2 hours away in Charlestown to prop open some doors and get fans running. ( I can't shut the data center down )

Does anyone know how long the computer room can run with the doors open and fans running before it gets overheated?