AirCon not cooling as expected

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  #1  
Old 11-17-17, 04:23 AM
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AirCon not cooling as expected

Hi,
Our company moved promises and before moving in we spec'd a aircon unit for the server room. However it is not cooling as expected - have we messed up?

We would like the room to be maintained at 21 degrees Celsius.

Here are the details;
Room is 2.7m wide X 3m long and 3m high.
No window and unoccupied 99.9% of the time. LED lighting off 99.9% of the time.
1 server rack with a total power consumption (as measured by the UPS) 1140watts.

We spec'd a 3.5kw (11,000BTU) Mitsubishi Air-Con (Int MSZ-DM35VA Ext MUZ-DM35VA)

In use when the weather was warmer (around 17 degrees) the room would struggle to get to 23 Celsius with the aircon set to its minimum of 16 Celsius.

Now its colder outside (6.7 Celsius) we can get to 21 Celsius.

Have we under spec'd the Air con or is it not as efficient as it should be?

Thanks for any advice
 
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Old 11-17-17, 12:09 PM
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First The M- series units are not designed for server rooms. The warranty is voided. You need to be using a P- series unit for server rooms. Was a heat load done on the equipment in the room? Do you have a total # of watts for the room? Sounds like you have more heat load than the unit can remove.
 
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Old 11-17-17, 12:41 PM
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21 Celsius is 69 degrees if my conversion was correct. Why do you need it colder than that.
 
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Old 11-17-17, 02:38 PM
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Looks like you need a larger AC unit. .
 
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Old 11-20-17, 01:15 AM
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Thanks for the replies guys.

We don't need it colder than 21c but when it was slightly warmer outside we couldn't get to 23c let alone 21c.

Mitsubishi have said the rating of the air con should be ok but that as airman,1994 has pointed out the M series is not intended for server rooms however they did say it could still work well.

Currently we can make 21c but I'm worried about what will happen when the warmer weather comes.

Thanks again guys.
 
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Old 11-20-17, 05:11 AM
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Are you qualified to determine the AC unit size? we usually gave all the spec's of the equipment in server rooms to an HVAC Co. and let them spec. the equipment,then it's on them if there is a cooling issue.
Geo
 
  #7  
Old 11-20-17, 05:29 AM
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This was a new build (not designed by us). During fit-out the room was designated by us as a server room requiring ac. The developer then chose a 3kw unit that was then increased by my boss to 3.5kw. The range was chosen by the developer. So there is a bit of both involved

Mitsubishi has agreed that although not the correct range it should still be adequate for our cooling requirements.

Now we know the wrong range of air con was fitted we will go back to the developer and see what they suggest.
 
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Old 11-20-17, 08:09 AM
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Being that the unit cools the room fine when its cool outside the size for the equipment load is correct. Sounds like the building load was not factored into the load.
 
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Old 11-20-17, 09:27 AM
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I had wanted to respond sooner.

Some things that weren't mentioned... are there any system registers or returns in that room ?
I've notice many of the server rooms I work in have an exhaust vent to remove the excessive heat trapped at the ceiling.
 
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