Server room cooling

[dirtychinchilla]

Afternoon,

This is completely out of my comfort zone, hence coming to you guys. We're trying to minimise our energy consumption at work, as I'm sure everyone else is. One constant load we have is the server room, both in terms of the servers and the air conditioning in the room.

It's not a big room, maybe 3 x 4 m, and it has one server rack in use.

We've been cooling it to 21C, but now we're heading into winter, we seem to be heating it to 21C, which is illogical. One school of thought is just to turn the air con off until it warms up outside. I'm not sure that this is a good solution as it could very easily be overlooked.

My thinking is that we need to measure the temperature of the rack (or the devices within, but that is much more complicated IMO) and regulate room temperature based on the temperature inside the rack.

This can't be a new idea. Does anyone know how we might go about it? We aren't afraid of investing in bits of kit if they'll save energy over time.

Thanks,

dirtychinchilla

 

[Armageus]

Assuming a standard split air con unit, can't you just set it to Cool rather than Auto.

It therefore should only cool if the room temperature goes above the set point, and will not heat at all (but the room temperature is unlikely to fall to a dangerously cold level with servers pumping out heat)

 

[dirtychinchilla]

Assuming a standard split air con unit, can't you just set it to Cool rather than Auto.

It therefore should only cool if the room temperature goes above the set point, and will not heat at all (but the room temperature is unlikely to fall to a dangerously cold level with servers pumping out heat)

Ah good point. We did fiddle with it a little bit, and it may be that taking if off cool was a mistake (assuming we did that).

 

[Semple]

How are the racks positioned? If it's literally just in the center of the room pumping out heat whilst the AC is trying to maintain the temperature of the whole room then that's extremely inefficient.

Ours have an enclosure in between rows where the racks face forwards on both sides, and the aircon is only pumped into the enclosure. The rear of the rack is then open to exhaust the hot air. It's much more efficient in the summer as you're not then trying to cool down an entire room.

 

[dirtychinchilla]

How are the racks positioned? If it's literally just in the center of the room pumping out heat whilst the AC is trying to maintain the temperature of the whole room then that's extremely inefficient.

Ours have an enclosure in between rows where the racks face forwards on both sides, and the aircon is only pumped into the enclosure. The rear of the rack is then open to exhaust the hot air. It's much more efficient in the summer as you're not then trying to cool down an entire room.

Hah exactly that - the rack is in the middle of the room. In reality, that means it's about a metre from the AC, but you're right - why cool the whole room. I'll look into that, cheers.

 

[WJA96]

If you are genuinely looking for efficiency then most servers I’ve seen are rated to run at 40C ambient so why are you cooling them to 21C? Even 30C ambient would make a huge difference to your energy bill when you’re cooling.

The servers are producing heat. Why not extract and use that heat in other areas of your building?

Is this not a possible use case for an air source heat pump?

 

[dirtychinchilla]

If you are genuinely looking for efficiency then most servers I’ve seen are rated to run at 40C ambient so why are you cooling them to 21C? Even 30C ambient would make a huge difference to your energy bill when you’re cooling.

The servers are producing heat. Why not extract and use that heat in other areas of your building?

Is this not a possible use case for an air source heat pump?

Morning. We're cooling the room to 21C, so I was thinking it would be better to monitor the actual servers instead, as you're sort of implying. No idea how we would go about that though, hence the post.

We could indeed extract the heat, you're right. Not sure how that fits into a potential air source heat pump, though? Air con units are essentially air source heat pumps.

 

[Zefan]

Morning. We're cooling the room to 21C, so I was thinking it would be better to monitor the actual servers instead, as you're sort of implying. No idea how we would go about that though, hence the post.

We could indeed extract the heat, you're right. Not sure how that fits into a potential air source heat pump, though? Air con units are essentially air source heat pumps.

Seeing as this is a cost saving exercise, any real modifications (that would prove costly in themselves) are likely off the cards I imagine? I think simply sticking the aircon to cool and moving it up a few notches (making sure to do so only as far as hardware documentation dictates) is going to reap large benefits on its own.

Not 100% sure why you're looking to monitor the temperature in the rack aside from ensuring that the delta between equipment temp and ambient isn't huge, but it should be as simple as checking the ILO/IRMC/whatever the hardware has for monitoring. If you want to tie the air con to this temperature instead of the ambient, the easiest way imo would be to get an external thermostat for your AC unit (presuming it offers this feature) and stick it inside the rack. I wouldn't bother with this, I'd just work out the average equipment:ambient delta and then set the ambient accordingly.

 

[WJA96]

Morning. We're cooling the room to 21C, so I was thinking it would be better to monitor the actual servers instead, as you're sort of implying. No idea how we would go about that though, hence the post.

We could indeed extract the heat, you're right. Not sure how that fits into a potential air source heat pump, though? Air con units are essentially air source heat pumps.

No, I’m talking about controlling the room temperature to a much higher level. It’s not 21C because that’s where the computers like to be, it’s 21C because that’s nice for the people. The equipment will almost certainly be rated to 40C ambient so why run it at 21C?

And if you put the air source heat pump (ASHP) in the server room it will heat a significant area outside, such is the multiplication effect of the device.

So yes, you will be looking at a substantial sum to install the ASHP and an installer should be able to tell you how much it will save you on heating costs through the cooler months.

 

[Semple]

21C seems rather high to me . As above you may be able to increase the temp if the servers aren't running hot.

I've just had a look at some of ours and can see inlet ambient is at 14C. But I know ours run under heavy load a lot of the time so they do get hot.

 

[Armageus]

21C seems rather high to me .

Same

We run our server room at 18C, but that's due to previous bad experiences with our site generator - whilst the Servers are good for over an hour on UPS, without site power or the generator running, the Air con units don't run, and the server room is uncomfortably hot in a short space of time.

At 21C i'm getting an email alert and jumping in the car to come and see what is going on

 

[Delta3D]

If you are genuinely looking for efficiency then most servers I’ve seen are rated to run at 40C ambient so why are you cooling them to 21C? Even 30C ambient would make a huge difference to your energy bill when you’re cooling.

The servers are producing heat. Why not extract and use that heat in other areas of your building?

Is this not a possible use case for an air source heat pump?

30c is far too warm for a server room ambient temp.

 

[WJA96]

30c is far too warm for a server room ambient temp.

Why? If the spec sheet on the server says up to 40C why is 30C too hot? I suspect it’s about a comfortable working temperature for the staff rather than any impact on the equipment. Besides, my calculations on a moderate air source heat pump would never let the temperature get that high.

 

[WJA96]

Same

We run our server room at 18C, but that's due to previous bad experiences with our site generator - whilst the Servers are good for over an hour on UPS, without site power or the generator running, the Air con units don't run, and the server room is uncomfortably hot in a short space of time.

At 21C i'm getting an email alert and jumping in the car to come and see what is going on

When you say uncomfortably hot - you mean uncomfortably hot for you, or the equipment?

 

[Armageus]

When you say uncomfortably hot - you mean uncomfortably hot for you, or the equipment?

Both.

The Servers (HPE) we have specify 35C inlet temperature as a maximum, and specify potential performance derating above 30C.

Additionally I'd rather not face the (admittedly small) increase in risk that running parts (Fans, Hard drives, PSUs, UPSes) hotter brings (especially when multiplied by a number of servers)

 

[WJA96]

I think the justification all of us will have to face in the very near future is the energy cost of running equipment so far under its rated performance characteristics. Given who you are, I know for a fact that you will have specified failover equipment and quite possibly swaps for your failovers so you have assets that you are protecting so you don’t need to use the other equipment you have.

And the price of energy has just gone up by a factor of x. At some point you have the possibility of sav8ng your employer a significant sum by running closer to the rating of the equipment.

I believe you are very conscientious and from your posts you strike me as a sensibly cautious individual. The OP wants to reduce energy. For me, in a properly set-up scenario with failover and cold-swap spare equipment I think the risk of running at 30C is acceptable.

 

[Cyber-Mav]

its -5c outside today. open window + deskfan?