Air Con recommendation?

[James Crosland]

We're moving in to a new compuiter room and i like people's opinion on the best way to cool it.

The room is faily small and we're going to have 2 rows of 5 racks. Underfloor air con isn't an option so we'll have to go for wall mounted.

The 2 options i can see is have the 2 rows facing away from each other, 2 cold corridoors at either side of the room and a big hot one down the middle.

Or turn the racks to face each other and have one cold corridoor down the middle and 2 hot ones down the outside.

I can see benefits for the latter - we need to "cool" less area at a higher power. My concern is where the aircon units sit - with them being wall mounted we'd likely have to mount 2/3 above one another and i'm not sure how this would affect performance.

Any comments welcome!

Cheers, James

[Colin Butcher]

Hello Jame,

There are a lot of other things to consider too, such as where the outside walls are, how the power and data cabling cabling should be laid out, ensuring that the air conditioning equipment doesn't ice up (or leak) and drip on things, ensuring that people can easily (and safely) work on the equipment in the room, what type of air conditioning units to use for best reliability and effective cooling, etc. etc.

You also need to understand the heat source density within the room as well as the overall heat load withing the room - for example modern blade type systems will generate a lot of heat in a small space and that can be difficult to cool with conventional air condiioning layouts. Thermall modelling your environment first may be useful.

I would strongly recommend bringing in a couple of companies that specialise in this kind of work and take their advice. They will have seen a lot more data centres and will have a better undestanding of what will fit your specific circumstances.

Cheers, Colin (http://www.xdelta.co.uk).

[James Crosland]

Hi Colin, thanks for your mail - we've done just that - arrange for a couple of companies to come in and have a look - one local and one larger. Will see what they say.

[pishoy.boushp.com]

i would also try getting a raised floor.

[Rob Leadbeater · Accepted solution]

Hi James,

Do ensure that the air conditioning companies that you talk to are experienced in cooling computer rooms. Many claim to be, but in reality will try to sell you office style "comfort cooling" air con units that simply won't do the job.

You need to be looking at "close control" units which are designed to run 24/7.

Airedale have a good range of units.
http://www.airedale.com

Do also ensure that whoever makes the final purchasing decision is aware of what they're buying... Close control units are more expensive than comfort cooling units, and consequently the quote from that supplier will typically end up in the bin. They will pay for themselves though.

I used to manage a smallish computer room, with around 12 racks of kit, so probably a similar size to yours. Originally this was fitted with two ceiling mounted comfort cooling units. When the heat output got too high, an additional two floor standing comfort cooling units were installed, against my advice. These did the job for a while, but the company got a big wake up call not long after when one of the units failed. The knock on effect from this was that all of the units stopped cooling because they got too hot ! It's quite scary being in a computer room where the temperature has peaked at around 50C. The racks were almost too hot to touch. Some of the servers never recovered.

Just before I left, an additional two ceiling mounted comfort cooling units were installed, to try and alleviate the problems - again the cheapest quote won, and 18 months later the company is still having problems with cooling...

Hope this helps,

Regards,

Rob

[James Crosland]

Rob, thanks for the advice. Couldn't help replying but our current smaller computer room has 5 racks, 3 wall mounted comfort air con units..... and 2 floor standing ones, 3 in the summer! It just sounded far too similar! To be fair this weas caused by the constant and rapid growth over the last couple of years to the point where the current room is bursting at the seams, i type this message from my desk with a 3/4 loaded rack behind me whilst the new room is being completed!

We have gone for 6 wall mounted relatively high powered units (as much as you can with wall mounted), 1 cold corridoor in the middle. The air con engineer is very confident it will be like a fridge in there, in a couple of weeks time we will know,


In regards to previous messages about underfloor air con - this is the way i'd like to go, but we have height regstrictions in the room that mean we can't raise the floor enough to have underfloor air con installed.

[Joshua Small_2]

For this many racks, you want to consider an air con unit which sucks ait from the hot air coridoor and blows it in front of your servers. If your current recommendations are for wall mount I'd look suggest alternate companies.

Several companies produce units which sit between your racks and will accomplish your goal. I agree with what was said elsewhere - wall mounted units are office comfy cooling units.

[James Crosland]

Thanks Joshua - the room is live now with the wall mounted units, and to be honest its freezing in there - i've left a jumper at work to put on whenever i go in - just like it should be!

We are probably just small enough to get away with wall mounted units - 9 racks, currently about half full, but the air con units aren't working at full speed anyway so we should be ok with the growth we've got room for.

[Rob Leadbeater]

Hi James,

Another word of caution... Don't set the aircon units too cold. Computer rooms should ideally be at around a constant 21C.

If your room really is freezing as you say, then you could be setting yourself up for a fall.

One thing that contributed to my previous problems, was setting the aircon units to as cold as they would go. All that does is to cause the things to ice up internally, and generate more water that needs to go somewhere when they defrost. Not ideal for a computer room !

Cheers,

Rob

[James Crosland]

Freezing was perhaps the wrong word - just feels that way comapratively to what it was before!

Our cool corridoor varies from 18 upto 21 with the hot corridoors about 6 degrees hotter, overall i'm pretty happy with how its turned out.