AC Split unit working under 16ºC

[springmaster]

Hi and Merry Christmas to all

I work for a company in Mozambique that does air conditioning work.

At 2 diferent sites we are facing the same problem:

in the server rooms, normal wall split units were installed and the users run them all the time at 16ºC. The sution line, although well insulated with armaflex is always condensating, creating drops on ceiling. We replaced the inslation but it is still doing the same thing.

Is this a insulation problem of the piping or can be related with the fact that the ac split units are runing at 16ºC?

[stufus]

Running the splits at 16c is defiantly not a good idea.I doubt there is anything in the server room that requires such a low ambient to operate,The splits probably never achieve set point and run continuously .And if you have any air breaks in the insulation this will cause the suction pipe to sweat profusely,if ice then starts to form on the evap coil this will only start to compound the problem as the back pressure starts to drop off
May be an idea to use thicker walled armaflex if the humidity is high
Try operate the splits a few degrees higher about 20-21c ,if they can maintain temp shouldn't have any issues
Cheers

Stu

[Brian_UK]

As Stufus said, raise the temperature set point.

Also make sure that the insulation is vapour sealed at all joints and ends; don't not squeeze it with tie-wraps.

[Brutus]

Maybe you have a humidity problem inside your server room beacause I have been to many server rooms and temperatures reaches up to 18 below deg C. As far as i know normal splits are for comfort cooling only and are not design for server rooms application instead try using presicion aircon that controls humidity and temperature. And for installation of refrigerant pipes do not install it above your server rooms or water drops pouring on your computers and servers will be your next problems.

[Magoo]

Install outdoor fan speed regulation to stop over condensing and system over performance, and condensation problem.

[mikeref]

Install outdoor fan speed regulation to stop over condensing and system over performance, and condensation problem.

OH MY! Magoo, you used the "O.C" word!!! Remember the thread started back some months ago ?? .. No such thing.. ask Gary. (Pssst! i know what you mean)

[paul_h]

Yes, you mean too low a head pressure

[dougheret0]

The problem here is the user, and you need to advise them. If you can obtain the specs for one of the servers, you will be able to show them that the units are rated for temperatures up to 40C with a rh range of 20 - 80%. IBM recommends a data center temperature of 22C.
http://publib.boulder.ibm.com/infoce...ditydesign.htm

Server rooms are generally not as controlled as data centers, and are usually contiguous with office space, where the dew point could occasionally rise above 16C, causing condensation on server cabinets. So 16C is definitely not a good idea.

However, the suction line condensation may still occur, even at reasonable space temperatures, so the insulation needs to cover all of the exposed suction-side components, have all of the joints sealed, and be finished with a tight vapor barrier.

[nevgee]

Along with the other posts, there is also likely chance the systems were sized incorrectly. Their total duty being used without consideration for the sensible load and shr of the indoor units.
Typical indoor AHU's have only 0.7 shr in which case they could be undersized by 30% and the user sees a low performance, hence turning down the stat to 16C

[Magoo]

Hi Mikeref and Paul.
I will wash my mouth out with salt.
magoo

[DTLarca]

Along with the other posts, there is also likely chance the systems were sized incorrectly. Their total duty being used without consideration for the sensible load and shr of the indoor units.
Typical indoor AHU's have only 0.7 shr in which case they could be undersized by 30% and the user sees a low performance, hence turning down the stat to 16C

The only stable solution to this is to use a larger indoor unit - not to also use a larger outdoor unit.

Where do you think the other 30% compressor capacity goes if there happens to be a shortage of moisture in the room?

[nevgee]

A differrent balance point will be achieved, with a lower suction pressure, and lower duty from the compressor.

[mikeref]

Along with the other posts, there is also likely chance the systems were sized incorrectly. Their total duty being used without consideration for the sensible load and shr of the indoor units.
Typical indoor AHU's have only 0.7 shr in which case they could be undersized by 30% and the user sees a low performance, hence turning down the stat to 16C

Too true, i've seen a/cs sized for specific applications only to find room layout has changed with extra equipment added or wall removed and another room added. Air-con now cannot cope with demand.

[springmaster]

Thank you very much for your coments.

We already advise teh user to set the temperature at 20 ºC, it is more than enough, but with no results.

We have insulated the pipes again and sealed the joints, but it is still droping.

We will take in consideration your comenmts.

Thanks again

[mikeref]

This condensation problem, is it moisture forming on the outside of insulation only? Is there condensation in other areas like under the evaporator? Assuming this a/c has refrigerant expansion at condensing unit, then both lines are independantly insulated right?

[Peter_1]

If you still have condensation, then you've used too thin isolation or low quality isolation or gaps.
If condensation comes on your isolation, then the isolation is faulty, not the split.
What band and thickness have you used? What thickness of isolation are you using, what brand of isolation, what type of that band. What's your SH and TE