Server Room - Amps to kW?

[Slim R410a]

Quoting a proposed new server room 4.7m x 3.4m x 2.5mH.

Client is installing 8No. servers. I've asked him for a heat output for each server but he is having trouble getting the info from his supplier.

Only info he can give me is that total amps of servers is 60Amp. (7.5A per server) Can I work out a heatload from this??

[frank]

Current multiplied by Voltage = Watts

60A x 230v = 13,800W

[Slim R410a]

Current multiplied by Voltage = Watts

60A x 230v = 13,800W

I've just looked that up on google, seems abit steep - 850w/m2! Would that really be the actual heat output? I'm sure someone said once as a rule of thumb 1kw per server.
Presuming also that the 60Amp total is the maximum load i.e each server will not be pulling 7.5A each.

[Sandro Baptista]

A rule of thumb should be used when we don't have more data. I think is more reliable using the Frank's info, despite I can agree that the servers wouldn't continuously pull the maximum nominal current.

How much can you save on 5,8 kW of refrigeration capacity? Almost nothing and you will sleep well because you will know there is no lack of capacity.

[TRASH101]

Frank is right. With servers the majority of the electrical consumption is dissipated as heat.

[Sandro Baptista]

Frank is right. With servers the majority of the electrical consumption is dissipated as heat.

I would say all because no work out of the system is done so by the first law of thermodynamics that electrical energy will at the final be converted on the heat.

[NoNickName]

That's not at all much. A common heat per surface in server rooms can be as high as 4kW per m2.
Recently I came across a server room with 48U crammed racks with a total power dissipated of 15kW per m2.
Telecom equipment in direct current is expected to reach 50kW per m2 in the next few months.

[install monkey]

kooltech state 500w/m2 for server roomsx4.7mx3.4=7.9kw-dont fit a wall mount because the surface area of the filter is small and will req constant cleaning-fit a 10kw inverter ull be ok!then fit a standby unit cw hard wired controller then a fesh air duct cw outside stat to bring in filtered fresh air only if outside is less than 20degrees for free cooling hey presto

[frank]

Don't forget that when sizing cooling units for server rooms, you should select the equipment on the SENSIBLE load, i.e if you had a 10Kw sensible load then a 10Kw fan coil will not do the job as this will no doubt be rated at less than 8Kw SENSIBLE cooling duty.

A lot of the installations I've seen, where split type units are installed, have been undersized.

Remember that splits are not really suitable for server room applications.

[Magoo]

3 phase servers.
volts x amps x 1.73 x power factor x efficiency/ 1000 = kws.
Servers are all high sensible heat, so include rehumidifiers and controls, add ingress heat as well from walls and ceilings and floor. Plus a large safety factor on total heat load.

[NoNickName]

Kooltech doesn't know what they are talking about.
Also remember that servers have an average life time of 3 years, while close control units have a life time of at least 15 years, 5 times as much as the equipment they are cooling, so your planning should look 5 generations of computers ahead.
Split inverter type systems are not the equipment to use, for multiple reasons, among which: their life time is too short (they are designed for summer cooling in residential areas), their reliability is not up to the service level required from datacom rooms, they don't provide sensible cooling, and ultimately inverter systems are useless in constant heat load rooms.

[acnerd]

Split inverter type systems are not the equipment to use, for multiple reasons, among which: their life time is too short (they are designed for summer cooling in residential areas), their reliability is not up to the service level required from datacom rooms, they don't provide sensible cooling, and ultimately inverter systems are useless in constant heat load rooms.

Close control upflow or downflow systems are always superior, but an inverter driven system will always be preferable to a DOL system. Compressor speed can be adjusted to maintain a superheat that prevents excessive icing up of suction line. If you are forced to put in splits, go inverter.

[NoNickName]

Icing of suction line is something unknown to properly setup datacom air conditioning system. Nor it is suction line sweating, as all heat is sensible.
It shouldn't be even considered as a contigency case.

[TRASH101]

Close control upflow or downflow systems are always superior, but an inverter driven system will always be preferable to a DOL system. Compressor speed can be adjusted to maintain a superheat that prevents excessive icing up of suction line. If you are forced to put in splits, go inverter.

NNN is of course right when dealing with a 100% sensible load and why on earth use an inverter when the compressor is likely to be at 100% if designed properly leaving the superheat control to the Expansion device as per normal design ethics. The invereter would be a waste of power.

And Sandro

I would say all because no work out of the system is done so by the first law of thermodynamics that electrical energy will at the final be converted on the heat.

It isn't very common for electrical energy to have a 100% energy conversion to heat, ..

[acnerd]

NNN is of course right when dealing with a 100% sensible load and why on earth use an inverter when the compressor is likely to be at 100% if designed properly leaving the superheat control to the Expansion device as per normal design ethics. The invereter would be a waste of power.

LOL, I'm not going to argue Porsche vs Vauxhall, just in my experience inverter driven is the better of the two cheaper ways to go.
Don't understand your comment on how inverters are wasting power?

[chilliwilly]

Ninety percent of the time, we always used to install Calderdale and Marstair splits in computer suites back in the eighties. Reason being they only contained a CPU, a couple of hard drives, a fast mag, two or three VDUs, A comms patch panel, a couple of modems, and a crude UPS, AKA a CVT. Most of the cooling load amounted to around four ton, approx 14 KW, this was due to the then TTL logic of the apparatus. Unlike the Cmos switched mode logic you get nowadays.

Invertor technology wasn't readily available back in those days, at least not at todays costs. The other ten percent usually had packaged type Isovel, Deltaclima, and the odd Airedale unit. I can understand the theory of invertors being an uneccessary requirement, but you have to allow for external ambience and off peak/out of use of the servers.

Also in todays more competitive market you have to consider giving them two quotes with a brief laymans note explaining the reason of differrent prices. On the other ten percent, the packaged units were occasionally set up as a master and slave configuration. But the Kent recorder only ever showed a totally straight lines at certain times of day and certain times of the year.

When the systems managers questioned why it only straight lined at these times, the usual unacceptable answer was given, the technology isn't available for the price you have paid. Of which a hand full of certain customers increased their budget for modifications in their variaton orders. Then the ducting was modified with an auto damper and bypass put inside it, allowing for better constant control of ambience. And the Kent recorder penning more towards a steady flat line rather than a squiggle.

Maybe if you look at installing fifty percent DOL, and fifty percent invertor controlled, as one of the quote options. At least then your customers budget might stretch for a few extras or a higher quality system.

[install monkey]

mitsubishi mr slim power inverters are commercial units-if sized correctly then the system will ramp down once the setpoint is reached as where dol compressors or 2 stage cooling bang on causing higher running costs,contactor wear plus poor performance until the pressures have stabilised and the tev has settled down-also mitsi 5yr warranty-but hey it aint my server room-rant over thanks

[NoNickName]

Guys, a 14kW room hardly qualify as a server room.
Ramp down when the setpoint is reached? Settle down? Clearly some fundamentals knowledge how server rooms are is missing.
I will open a separate post concerning the failure of concept of digital scroll compressors.

[chilliwilly]

mitsubishi mr slim power inverters are commercial units-if sized correctly then the system will ramp down once the setpoint is reached as where dol compressors or 2 stage cooling bang on causing higher running costs,contactor wear plus poor performance until the pressures have stabilised and the tev has settled down-also mitsi 5yr warranty-but hey it aint my server room-rant over thanks

Mits units tend to be invertor recipricating pots and have a very high reliability record. I fit four second hand ones about five years ago in a restaurant and kitchen and their still going strong. The only problems they have is in the kitchen with the AH filters getting filthy and they forget to clean them, causing the obvious. Other than that when the set points are satisfied, they ramp down to to an average of sixty to eighty percent capacity in the middle of summer.




The next project I've been asked to look at is reclaiming heat from the kitchens condensor units or the extract canopy, to be used for an air heat source for heat pumps for the dining area. I haven't had the time to get my head around it yet, but there's plenty of food for thought for when they refurb. And they have requested mits units again.

[mad fridgie]

Heat load sorted by others, amps * volts = watts. heat produced!
if you are going to use an off the shelf "Comfort cooler", then you need to grossly over size, run the indoor fan speed on max, and capacity control the compressor, inverter (VSD) is OK.
This will keep the SST high giving high sensible cooling and little if any latent cooling.
You may find that these servers are just big PCs and can work satisfactory in a large working ambient range. (most electronics come with a working range of temps and humidity) Check this first!
Low humidity can cause static, so if you install the wrong gear and short out the servers because you AC is sucking out to much moisture, do you pay to replace the server and the data lost?

[Sandro Baptista]

It isn't very common for electrical energy to have a 100% energy conversion to heat, ..

Let focus on the present case: even supposing that the energy spent by the server is to generate shaft power to an electric motor the final result would be the generating of heat because no work get out of the system.

[ruzgar78]

current multiplied by voltage = watts

60a x 230v = 13,800w

p=i2 * v

formule

[Sandro Baptista]

P=I^2*V? No you're confusing with R*I^2.

[Makeit go Right]

a) I would say using Amps-to-Watts/kW is quite valid but you need to be sure of the amps figure. The IT guy will add up all the figures in Computer manuals, which is not so good as it gives you max figures. Great for cable and MCB sizes but when establishing the computer heat dissipation it will be higher than the actual. Ideally, the computer/comms kit would be in operation and you could measure the amps drawn, and go from there.

b) On the sensible heat issue, I saw that Sanyo can match a 14kW ceiling suspended with a 10kW condenser, to give a high sensible heat ratio and about 10kW sensible cooling in the room. They can mix and match their kit and are able to limit evap off-coil temp, if needed to deal with freezing coil issues.

Anyone have some comments about this mix+match of condensers/room units? Any problems with doing, providing manufacturer is happy/keen? Yes a high faluting Denco/Airedale monster would be correct and all of that....skip past all that lot, please. Just splits, eh?

c) With inverter/on-off systems, I think the inverter is best in a computer room as it holds the room temperature steady, rather than the bouncing up and down as the on-off kit switches on and off. The electronics do not like changing conditions...much better with a stable constant temperature in the room.

[NoNickName]

Great for cable and MCB sizes but when establishing the computer heat dissipation it will be higher than the actual.

The max heat dissipation is the energy supplied by the grid. It can't be higher.

Ideally, the computer/comms kit would be in operation and you could measure the amps drawn, and go from there.

It is a fact that the VA declared on the plate of computers does not represent the actual heat dissipation, which is lower.

b) On the sensible heat issue, I saw that Sanyo can match a 14kW ceiling suspended with a 10kW condenser, to give a high sensible heat ratio and about 10kW sensible cooling in the room. They can mix and match their kit and are able to limit evap off-coil temp, if needed to deal with freezing coil issues.

So they increase the condensing temperature to increase the evaporating temperature. Unfortunately this is bad for the COP and power consumption. Reducing the latent heat is only effective when the actual heat exchange surface is increased.

c) With inverter/on-off systems, I think the inverter is best in a computer room as it holds the room temperature steady, rather than the bouncing up and down as the on-off kit switches on and off. The electronics do not like changing conditions...much better with a stable constant temperature in the room.

ASHRAE guidelines for datacom application, published in 2009, state exactly the opposite. They are forcing the datacom equipment manufacturers to allow for larger temperature ranges.

[install monkey]

this discussion has been ongoing for nearly 2 months.did any a/c get fitted,or did the customer go b&q and get a couple of portables and cook his servers? come on slim r410a do tell.

[Greengrocer]

If it must be splits try Mitsti Electric's new High Sensible High Wall split - 10kW indoor matched to a 6kW outdoor = 6kW total cooling with a 0.96 SHF. Download their new 2011 catalogue - page 84 as stamped or page 47 when reading PDF.
As for the load if client can't give you accurate data you must state what you are basing your selections on.
@800watts/m2 sensible load = 12.8kW.
@1,000watts/m2 sensible load = 16kW
Round up to 17kW.
Select 4 off above Mitsi systems at 5.7kW sensible each. 3 for the load & 1 for standby.
Let them all run together at part load or, buy one of Mitsi's run & standby Panels (in controls section of Cat). Client can also have Text message alarms if required.
Only problem will be finding correct wall position for 4 indoor units that are 1,017mm wide (excluding pipe-work) in relation to position of server cabinets.
Also make sure the server cabinets don't have solid glass doors. Perforated doors or no doors at all with high walls facing the front of the cabinets.

[Slim R410a]

Hi Guys,

Still no movement on this job! The server room is not built yet, all I have done is sent the guy a sample quote for a 10kw wall just so he could get an idea of costs, I told him he is prob looking at 2 or 3 of these.

I chased up yesterday, he is still waiting on the actual heat output for the servers. His company is electrical/mechanical he is not the direct customer.

I was thinking what if the 60A he was on about was the breaker size required to the server room?? i.e this will be approx 1.5 times the maximum current.
(40A x 230v = 9.2kw)

[Greengrocer]

Hi Guys,

Still no movement on this job! The server room is not built yet, all I have done is sent the guy a sample quote for a 10kw wall just so he could get an idea of costs, I told him he is prob looking at 2 or 3 of these.

I chased up yesterday, he is still waiting on the actual heat output for the servers. His company is electrical/mechanical he is not the direct customer.

I was thinking what if the 60A he was on about was the breaker size required to the server room?? i.e this will be approx 1.5 times the maximum current.
(40A x 230v = 9.2kw)

The load could be any of the suggestions made previously. Like you we are all guessing. Also don't forget the fabric gains which won't much but still add to the total for the room.
If they can't tell you what the server load is then you have to tell them what assumptions you are making otherwise it could come back to bite you.
Also ask for a drawing or sketch of the server cabinet layout in the room & ask them what their plans are for future expansion. As sure as eggs are eggs they will add more servers in the future. So, do they want you to allow for that extra cooling capacity now or not? It's easier and cheaper to install the extra capacity now than later in a working room.

Note that a nominal 10kW high wall (Daikin / Mitsi) only does about 6.5kW sensible cooling because they have a 0.7 SHF.
e.g. Mitsi PKA-RP100 / PUHZ-RP100 does 9.2kW total at UK conditions. It has a SHF of 0.73 so the net sensible capacity is 9.2 x 0.73 = 6.7kW (maybe even less capacity if you have a longish pipe run).

So for a room load over 13kW sensible you will need a minimum of three nominal 10kW systems!
The other problem is that with a 0.7 SHF the std 10kW splits will extract too much moisture & create low RH conditions which promotes static electricity.

The new Mitsi system I mentioned earlier will give you about the same sensible capacity per system & it's cheaper than the standard 10kW split!! Best of all with a SHF of 0.96 it won't dry the room out anywhere near as much and it has a higher EER than the std 10kW split.
However, I reckon you'll still need at least 3 systems though.

Of course the other option is to go with a pukka close control system. 2 off 12/15kW sensible free standing systems on run / standby. Problem is I doubt whether you'd be able to fit them in the room (bigger than a large server cabinet), they will need a 3 phase power supply & they'll probably take 8-12 weeks to be built & delivered - which is why splits get used in small server rooms.
Think we've been here before in some other threads.

PS. I don't work for Mitsi it's just that they are the first mainstream manufacturer to offer an "official" high SHF high wall split for server / comms rooms. Ticks all the boxes that I & others have been banging on about for the last god knows how many years.
Mark my words now that Mitsi have this system available it won't be long before Daikin come out with a similar system to match or better it. I just wonder why it's taken them so long.

[NoNickName]

Pukka? Plenty of close control manufacturers with shorter lead times and similar sizes to racks.

[Greengrocer]

Pukka? Plenty of close control manufacturers with shorter lead times and similar sizes to racks.

Like who?
Any indoor close control unit over 10kW is at least a 1m2 or larger & with a free blow plenum on top many are too high for some rooms as well - not to mention getting them up to the 4th floor as they weigh a ton. Many also can't do very long or vertcal separations without double suction sizers either.
The server rooms we are talking about are quite small & many are no bigger than a broom cupboard & there's no 3 phase on site or nearby.

[NoNickName]

http://www.montair.it produces a 19kW close control units in 750x715mm footprint.

[Greengrocer]

http://www.montair.it produces a 19kW close control units in 750x715mm footprint.

I can't find or download any technical content from that website. I've heard of Montair by they are not actively sold in UK - to my knowledge.
Still looks too tall / heavy for the size of rooms we often see and I bet they are only available in 3 phase power supplies.
Don't get me wrong where we can I would always use a close control system over a split (that assumes the client is willing to pay twice as much as splits). In fact last year we supplied & installed a rather unique system for a university server room. It was a downflow cooling only unit with front discharge (above the floor) & top return air. It also had an inverter compressor (LG!) so could handle the initial 6-7kW load but could ramp up to a full 12.5kW when they expanded the servers later on. We bought the system via Lennox in the UK but it was made by Hiref of Itally. We probably paid through the nose but it was the only system I could find with a front discharge (displacement) supply air arrangement, inverter, variable speed EBM fan, R410a & EEV. Quite a good unit but we had a few fromblems with it e.g. schraeder caps not tightened at factory so we couldn't pull a vacuum on the pipe-work - sod's law it was the schraeder in the most awkward place behind the compressor. Pressure test was fine but couldn't pull a vacuum. Took us over a day of head scratching to find it. We also had a problem with the EEV which needed an new stepper motor under warranty. Other than that it worked well but was a pig to manhandle into the room because it weighed over 250kg. Also took up a lot of floor space in what was a quite a small room.
Other than that it was a good solution.
BTW. This was a replacement for a 10kW Hitachi fixed speed R22 high wall unit.

[NoNickName]

I can't find or download any technical content from that website. I've heard of Montair by they are not actively sold in UK - to my knowledge.

Try with Aquacooling of Fareham, Hampshire.

Still looks too tall / heavy for the size of rooms we often see and I bet they are only available in 3 phase power supplies.

The three smallest (up to 11kW cooling capacity) come with single phase power supply.
The 11kW model weighs 230Kg, but the 4 panels and the fan are removable to reduce the weight by about 50Kgs.

[Greengrocer]

Try with Aquacooling of Fareham, Hampshire.



The three smallest (up to 11kW cooling capacity) come with single phase power supply.
The 11kW model weighs 230Kg, but the 4 panels and the fan are removable to reduce the weight by about 50Kgs.

Aquacooling - these guys are installers as well. I would never purchase equipment from what amounts to a competitor. They can't have it both ways. You are either a manufacturer / distributor or, you are an installer. You can't be both in the mass market side of our business. As the old saying goes "you cannot run with the hare and hunt with the hounds".
There are a few companies like this that have issues with, one of which I used to work for, but I'll refrain from naming them here.

I still think CC units are too big, heavy & expensive for small server rooms. They simply don't fit the bill for the average "broom cupboard". Saw one last week - it was only 6m2 and only just big enough for a server cabinet let alone the AC. I couldn't even find space for a 2nd system on the wall as a back up. I quoted a 5kW sensible (nom 7.1kW) high wall at around £3,200 & lost the job to a "man in a van" who's put in a 3.5kW total cooling MHI system that doesn't even have HP control so it won't operate below 18c ambient. When he finds out he'll have to revisit and spend some money on it to make it run but it still won't handle the 4kW sensible load. Client has wasted their money - & I've told them so. The only bright side to this sorry situation is that when they come to their senses I may get a crack at putting it all right.
Most clients simply don't have the budget for CC systems. Let's face it most of them have been using portables with hoses out of the window they bought from a DIY store. It's only when they have problems with them that they want something more suitable. Even a professionally installed split system is megga bucks to them.
Sorry rant over.

[NoNickName]

Ok, I see your point. In case, you can also try with Klima-therm of Wimbledon. Hope you change your mind!

[Greengrocer]

I take it you work for Montair then?

[NoNickName]

Sorry, but it's forbidden by the forum rules. I already pushed to far.

[frank]

I take it you work for Montair then?

Put it this way Greengrocer....you don't need to ask this question twice

[al]

Edpac http://www.edpac.com/QueryPage.aspx are also worth trying, good prices especially compared to lennox etc. still pricey though compared to splits!!

I'd say 70% of server rooms here are split cooled, standard inverters, if it doesn't work...well add another one

alec

[Greengrocer]

Edpac http://www.edpac.com/QueryPage.aspx are also worth trying, good prices especially compared to lennox etc. still pricey though compared to splits!!

I'd say 70% of server rooms here are split cooled, standard inverters, if it doesn't work...well add another one

alec

I used to sell Edpac in the UK back in the late 70's. Went to their place in Philidephia for training & watched Debbie does Dallas on a 40ft wide drive in movie screen from my hotel room window!!

[Greengrocer]

Edpac http://www.edpac.com/QueryPage.aspx are also worth trying, good prices especially compared to lennox etc. still pricey though compared to splits!!

I'd say 70% of server rooms here are split cooled, standard inverters, if it doesn't work...well add another one

alec

Put it this way Greengrocer....you don't need to ask this question twice

Yes I know. I smelt a rat but just wanted to make sure.

[al]

They're made in Cork now along with some lovely Murphys!!

Debbie on a 40ft

Hope you had jumbo kleenex!!!

alec

[Greengrocer]

They're made in Cork now along with some lovely Murphys!!

Debbie on a 40ft

Hope you had jumbo kleenex!!!

alec

I needed more than kleenex. The Edpac sales guys laid on "evening entertainment" in Philli & when I transfered up to NYC for a few days before flying home. Had a ball in the Barbazon hotel overlooking central park if I remember correctly. After all it was the 70's!! Sh** we had some good times back then. It's all got far too serious these days.

Mind you I also used to visit Dublin & Belfast when I was with Carrier. The guys at the then Walker A/C (independent Carrier distributor) always showed us a good time as well. More drink based as you would expect. Got wrecked more than once or twice on the black stuff, chasers and oysters.

[NoNickName]

Yes I know. I smelt a rat but just wanted to make sure.

No need to be rude or offensive. I just wanted to give my 0,02 and inform you that some of the issues you presented have already been addressed and resolved. I'm sure there are other manufacturers too.

[Greengrocer]

NoNickname. I didn't mean to be offensive. The phrase used is a "figure of speech" often used in certain situations (UK/US/AU etc). Perhaps this was not the right situation. So if offence was taken I appologise - none ws intended. Just wanted to see where you were coming from, so to speak.

You are right that there are plenty of people on the forum who work for manufacturers & your / their help with certain equipment and technical related issues is invaluable. However, when discussing more theoretical or application based subjects I find it is better to know what the other people do or who they work for since this can affect the views stated & the way other people "read" the thread. Hope that makes sense.
This is why I stated earlier in the thread that I did not work for Mitsubushi because some people could have come to that conclusion.

[Sridhar1312]

If SERVER make is known like DELL, IBM etc then you can get the heat dissipation of the servers from their website. Otherwise the heat load taken more and heat dissipation is less it can be high RH and low RH when the heat is more than considered. The air quantity will come any where between 550 cfm to 600 cfm per TR and only precision units will be able to take care of this.

[Makeit go Right]

I went to a London Server Room few weeks ago where they had 2-20kW CCUs (duty-standby) parked in the room. Took up more space than the servers.

Customer wanted to throw them and install wall splits so as to reduce the room size and make better use of his ft2 rentable floor space.

I explained about humidity control etc but quickly realised that whilst their eyes were open, the ears were fully closed. So, those nice CCUs will be heading to scrap in the near future -- painful, but it is an install