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  1. #1

    Smile Condensers located indoors overheating - possible quick solution?

    Hi all,

    I've got a problem with an air conditioning installation. I'm not in the business of air conditioning, and our supplier has been contacted and will be along next week. However, please read my story and see if it makes sense . Thank you for any help you can offer.

    So, I have about 15kw of computer equipment being cooled by an air conditioning system with two condensers. (Just to check, they look a bit like http://www.mustknowhow.com/wp-conten...singUnit02.jpg , with a fan exhausting hot air on the front, and a radiator on the back). The setup is running correctly and was serviced recently. If it matters at all, the install is in the UK, where peak daytime temperatures don't go above 30oC much.

    However, with recent hot weather, the computer equipment has been overheating (aircon is set to 18oC, but it's actually giving out 24oC).

    Looking at how the condensers were installed, they are installed in a room, under a road. The room is 4m wide x 4m long x 2m high, with a standard door sized opening to the open air. Two condensers sit on the ground in the middle of the room. The only ventilation is the door sized opening. The room gets very hot as you might expect; it's currently 40oC (104F) in there.

    I think the same air is remaining in the room, and being circulated over and over through the condensers. Thus, the air is getting very hot, and they work less efficiently. Is this likely to be correct?

    If this is correct, it doesn't seem efficient. It would seem easier to cool using colder air, rather than hotter air. We've contacted our air conditioning supplier to see about moving the condensers outside (which is possible, there is space). As far as I am aware, they were only located inside, due to cosmetic reasons.

    I'm on the search for a quick fix, until the condensers are moved, or otherwise our supplier comes to visit.

    In the short term, I was considering getting some flexible ducting (e.g. http://www.ductstore.co.uk/acatalog/..._Flexible.html). Then, duct taping this to the exhaust grille of each condenser, and putting the other end of the ducting outside. This way (I hope), the heat would be dumped outside, instead of in the room.

    Is this idea likely to work, or be effective?

    Does anyone have any other ideas?


    thank you for reading ,

    c9
    Last edited by Cloud9; 06-03-2011 at 08:26 PM. Reason: deleted some extra words I typed in by mistake

  2. #2
    Join Date
    Jun 2010
    Location
    S. Texas
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    63
    I'll jump in, yes the air should not be recirculated as it doesn't give up the heat content.
    Your ducting the heat outside will help if there is cool air allowed in to the room to replace it, in fact that will solve the problem permanently.. Use a large duct 8" at least. . The A/c can only maintain a certain difference between inside and out, if the outside (condenser ) gets too hot, the inside (cool ) temp has to rise.

  3. #3
    Join Date
    Aug 2006
    Posts
    2,594
    Unless your Condensor motor is oversized for the job, you will have problems with it overloading due to the duct restriction. Most condensor motor are sized just big enough to do the job, and have no service factor. IE The max amp draw is 2.4 A, checking it with your meter, you will commonly find it drawing 2.2 to 2.4 Amps. Put duct work on that propeller fan, with a couple offsets, and you are over amping the motor. If you are rated 2.4 A and only drawing 1.8 A, you have some leeway. Used to always cringe when I saw computer room heat rejection in a commercial garage. BTW some Computer room AC manufactures, namely Liebert, make Squirrel cage heat rejection that can be ducted.

  4. #4
    Join Date
    Mar 2011
    Location
    East Coast FL
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    1,058
    OP you are correct , the air cooled condensing unit/s need to be relocated , condenser air re-circulation is a major problem.

    Propeller type fans have very limited static pressure capabilities , and are not designed for any type of discharge air ductwork.

    Centrifugal type fans are well suited to remote ducting and are often used with indoor air cooled condensers.

    What you have is a mis-application / bad installation.

    Happens all the time.

    Ace contractor and currency will be needed to correct problem.

  5. #5
    Join Date
    Feb 2010
    Location
    In a boiler room
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    7,073
    I've seen it work when they have a large free air opening into the room and an exhaust fan at the other end.

    Not the way I would do it but it did work. A couple walkin cooler cond units and a mini split cond unit inside a room.

  6. #6
    Join Date
    Sep 2007
    Posts
    175
    Agree flex duct won't get you where you want to go. Temporary but marginal solution: place large, powerful 3-4 ft diam floor fan in door opening, you want to use up the bottom half of the door space. Run this fan on hi-speed, thus forcing outdoor air in. Hotter indoor air will be forced out the top half of the door opening space. This isn't much but better than nothing, and cheap. Agree condensing units must be moved outside. Remember, the first word in "Air Conditioning" is "Air"

  7. #7
    Join Date
    May 2007
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    Dry as a bone Tucson
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    quick fix

    Cut in a large vent into the roof. Then you can use the door as an intake. Physics will take care of the rest. Then you can move the cu's when you find the right contractor.Or just leave them if this solves your problem.Which more than likely will.
    Some Talk, Some Do
    "keeping condensing pressures low and evaporator pressures high"
    "Some customers are more interested in comfort than energy savings"
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  8. #8
    Join Date
    Nov 2006
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    Southeastern Pa
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    Whenever I see condensers located indoors in situations like this, I have to ask myself, "what the **** were they thinking"????

    The idea is to move heat. The only really good place to move heat "to" is outdoors.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

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  9. #9
    Join Date
    May 2011
    Location
    New York
    Posts
    307
    Quote Originally Posted by tbirdtbird View Post
    Agree flex duct won't get you where you want to go. Temporary but marginal solution: place large, powerful 3-4 ft diam floor fan in door opening, you want to use up the bottom half of the door space. Run this fan on hi-speed, thus forcing outdoor air in. Hotter indoor air will be forced out the top half of the door opening space. This isn't much but better than nothing, and cheap. Agree condensing units must be moved outside. Remember, the first word in "Air Conditioning" is "Air"


    Cheapest and best idea untill you get them moved
    Extended dehydration is the key

  10. #10
    Join Date
    Jan 2008
    Location
    LEHIGH VALLEY, PA
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    162
    hi c9 , i am originaly from the uk , and dont overestimte the just for ashetics scenario, so often , planners, designers, counclis , just would not listen to practcal engineering common sense, and a/c equipment just had to be hidden , if resiting is not allowed as previous posters have said , provide some positive fresh and exhaust airflow , better still make a plenum if practical your a/c guys should be able to advise and deal with that , good luck . but as the room is under a road dont go cutting to big a hole in the roof pedestrians might just drop in .

  11. #11
    Join Date
    May 2007
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    Dry as a bone Tucson
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    Red face Yikes

    in a room, under a road

    Some Talk, Some Do
    "keeping condensing pressures low and evaporator pressures high"
    "Some customers are more interested in comfort than energy savings"
    Blog
    Web
    Facebook


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