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  1. #14
    Join Date
    Dec 2003
    Location
    45th Parallel
    Posts
    954
    Quote Originally Posted by jayguy View Post
    all of this talk about fixes to the issue...how about cleaning the coils? keeps the fan motors online, keeps the fan blades intact and keeps the energy bills down.


    crazy ideas, i know, but it seems to work well.
    but it's so much more fun to modify and tweak stuff. Coil cleaning is just BORING!! and you get all wet!
    “If your work speaks for itself, don't interrupt.” ~Henry J. Kaiser

  2. #15
    Join Date
    Nov 2011
    Location
    Olive Branch, MS
    Posts
    2
    We have placed breakers on the individual fans to keep one that goes bad from blowing fuses and stopping / single phasing other fans.
    Fins in need of combing would also increase the drag through the coils and thus windmilling.
    We have some RTAAs where previous contractors sprayed water on the coils for extended periods and they have a heavy build up of minerals on them that makes this problem worse. Early RTAAs had issues with the fans staging up too slowly and needed some software upgrades. Between that and slide valve problems that often present as head pressure / oil flow problems, their solution was to spray the coils with water.

  3. #16
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
    Posts
    4,355
    Quote Originally Posted by drivewizard View Post
    but it's so much more fun to modify and tweak stuff. Coil cleaning is just BORING!! and you get all wet!
    no, your NEWBIE gets wet while you drink coffee and talk up the secretary!
    "Mother" is the name for God on the lips and hearts of children....The Crow

  4. #17
    Join Date
    Nov 2011
    Posts
    24
    Quote Originally Posted by jayguy View Post
    no, your NEWBIE gets wet while you drink coffee and talk up the secretary!
    Make sure you give him the purple stuff. It bites real good when you get the overspray.

    There are still issues as these machines get older that a coil cleaning just doesn't cure. I have clean coils and it is cool these days out there when I get failures. These compressors don't unload. It cranks up quick and cycles off not a good thing for a 100 ton pump.
    Time to pull the compressors apart and do some serious surgery. Oh yea the bosses are gonna cry when they get this bill.

  5. #18
    Join Date
    Mar 2009
    Location
    Mid-Mo
    Posts
    3,595
    Wouldn't a vfd go out on over current if the fan is spinning backwards while it was commanded off?

  6. #19
    Join Date
    Dec 2011
    Location
    dubai
    Posts
    10
    i have also same problem in the trane chiller model rtaa condenser fan runing backword durling winter time only then i have to stop all chiller and start then it will be o.k

  7. #20
    Join Date
    Nov 2011
    Posts
    24
    It looks like its running backwards but its actually spinning from the neighboring fan. make sure the coils are clean. I want to find some shutters to mount on the fans

  8. #21
    Join Date
    Dec 2011
    Location
    dubai
    Posts
    10
    Quote Originally Posted by chnrgr View Post
    It looks like its running backwards but its actually spinning from the neighboring fan. make sure the coils are clean. I want to find some shutters to mount on the fans
    thanx for your replay chnrgr now i have compressor defictev on the same chiller just i want know its esy to open the compressor on the site or it required to remove it from chiller and the motor stator it can be removed easly or not

  9. #22
    Join Date
    Nov 2011
    Posts
    24
    Quote Originally Posted by mustafaali View Post
    thanx for your replay chnrgr now i have compressor defictev on the same chiller just i want know its esy to open the compressor on the site or it required to remove it from chiller and the motor stator it can be removed easly or not
    I have been told you can do it onsite but you have to know what you are doing. Most of the guys I know recommend pulling it.

  10. #23
    Join Date
    May 2011
    Location
    NC Foothills
    Posts
    70
    I have pulled the stator out of a 100 ton compressor before. DO NOT wish to do that again ever! In a shop with proper tools and on a work bench maybe but never again in the field.

  11. #24
    Join Date
    Dec 2009
    Location
    Hotlanta GA.
    Posts
    214
    THE OLD FANs ON A TRANE RTAC !!!
    Well for the fact of clean coils; what presents a restriction to air flow ??? A "CLEAN" coil, or an open airway between fans ???? So take your "CLEAN" coil line back to TRANE !!! How does one expect the air to come through the coils if right next to the running fan is an open area for free air flow, a baffle plate and or a cover back draft damper system would increase the air flow through the coils as needed per fan running. MAYBE< JUST MAYBE if they designed it right we wouldn't need 28 fans per chiller x 6 units here = 168 fans with a 60% fail rate so far in 4 years.

    VFD !!! Yep, if your load is so low, a greater number of us are at a place that has a load that will never get low enough to have just one VFD running, and at the $$$$$$ TRANE ask for those things, I just jump out and say run you little buggers............constant 75 - 80% load 7/24.

    NOW let’s talk short cycle air flow >>>>> that’s were the air coming out the top comes right around back into the side of these beast, EVEN with the required 12 feet between units we see an entering temp of 115 / 125 on a 97 deg. day, no fancy calibrated test instruments’ needed. Just walk down between them, my $1,274,852 micro chip implants on my finger tips and forehead will confirm it !!!!

    So let the comments continue, may your rain suit stay dry and keep the wind at your back, that "BLUE" stuff will tell on ya !!!

    Another brilliant idea, let’s have them crawl up under inside the thing to clean these coils, BRILIANT< just BRILIANT !!!

  12. #25
    Join Date
    Mar 2008
    Location
    NC
    Posts
    1,460
    I've used the anti windmill device on this page
    http://catalogs.johnstonesupply.com/...l.asp?page=195
    on smaller carrier units that had the same problem.
    Used to take care of an rtaa240 that had the same problems mentioned in this thread. Never thought to try the brake.

  13. #26
    Join Date
    Dec 2009
    Location
    Hotlanta GA.
    Posts
    214
    Interesting, what material is the rod made out of ??
    How much time now since installed, did it do the job ??
    I could make some money on these ..............!!

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