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  1. #1
    Join Date
    Jun 2016
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    Gordo, Alabama
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    I need an Opinion????

    I have 2 series R trane centrevac chillers, they run lead/lag weekly and alternate at a specified time each week. About 3 weeks ago we had to drain the cooling tower and replace a transmission, once we replaced it and started building the water back up, we started the chillers up and they ran fine. Monday comes around and we were getting an alarm on chiller 1 for condenser water flow, it had an old water flow switch on it , so we decided to change it out and replace it with a new one because the trane tech that came out said it was bad. So we change it out, wire it up then system comes on and off, runs for 2 minutes, then cycles off, so on and so forth. So I jump it out and it runs fine. now this is on the condenser side not the evap side. So we get trane tech # 2 out there to look over it thinking it may be something within the programming or interface from previous work on system done before I got there. Everything is checked and its ruled that it could of been the wires not seated properly behind screw or even insulation preventing a good connection, so he wires it up and it runs, runs, runs, without a hitch......Then lunch time comes and what do you know it goes back to cycling on and off, so I jumped it out again and its running fine.
    So with that being said , powers that are higher than me are wanting to drain the cooling towers, change out some faulty butterfly valves, check the strainer even though were pretty sure its clean, fill it back up and see what happens....Now I have read some on the flow swithches and from what I have read it mentions leaving 4-5ft on each side of switch as far as pipe goes...As for how this one is, you have plenty of pipe before the switch, but directly after the switch maybe 8 inches you have a 90 going down into the chiller, which could be turbulent but lets face it , the chiller has ran fine over the years up until this point with it being located there. So am I missing something, or overlooking the obvious.

  2. #2
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
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    Quote Originally Posted by LSullivan View Post
    ...check the strainer even though were pretty sure its clean... .
    My vehicle won't fly in the air, even though I am pretty sure it's a plane...perhaps I should check.



    Quote Originally Posted by LSullivan View Post
    ...So am I missing something, or overlooking the obvious.
    You mess with the tower and now you have tower flow issues...


    Did you have pressure measurements taken? What were those measurements? (By the way, "fine", "good", "ok" and the like don't count).

    Got a chiller model number? Hard to troubleshoot from over here without any real information.

  3. #3
    Join Date
    Feb 2004
    Location
    Northwest GA
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    What Jay said, check your pressure drop across condenser barrel. Just because something has worked for years doesn't always mean it was right. At the very least the machines should be tested for flow failure on the condenser and evaporator annually. This helps prevent uh-ohs like what you have here. If it's a paddle switch I would seriously ditch it and go for a pressure differential type or thermal if you have the $$$. Paddle switches are way old school and far too often not installed properly and never tested or maintained. Same goes for pressure differential switches though, no one seems to ever check this stuff. Many times we find the troublesome flow switch jumped out. Permanently. No one ever seems to know who did it or when. Kinda like when on Cops they bust somebody and the perp says "it's not mine" LOL.
    Test your safeties annually, fix what's broke, make sure it works. EOS
    Superheat, that must be REALLY hot.

  4. #4
    Join Date
    Apr 2003
    Location
    St. Louis
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    When you pull the flow switch check to see if was installed with a welded thread o let. A lot of times the paddle doesn't have enough space to travel back and and fourth. The pipe might have to trimmed on the inner edge. Also there's time where the pump gets air bound, hook a gardenhose up to the suction of the pump turn it on full, let it for a while till line line is full.

  5. #5
    Join Date
    Aug 2009
    Location
    Prattville, Alabama
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    Quote Originally Posted by servicefitter View Post
    When you pull the flow switch check to see if was installed with a welded thread o let. A lot of times the paddle doesn't have enough space to travel back and and fourth. The pipe might have to trimmed on the inner edge. Also there's time where the pump gets air bound, hook a gardenhose up to the suction of the pump turn it on full, let it for a while till line line is full.
    I've learned to always trim down the width of the entire paddle to match the width where it attaches to the switch.

    And, of course, make sure the paddle's not too long.

  6. #6
    Join Date
    Apr 2003
    Location
    St. Louis
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    Paddle might fit fine but if the pipe at the bottom of the thread o let isn't bigger than the hole the paddle might not have full motion back and forth.

  7. #7
    Join Date
    Aug 2009
    Location
    Prattville, Alabama
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    Quote Originally Posted by servicefitter View Post
    Paddle might fit fine but if the pipe at the bottom of the thread o let isn't bigger than the hole the paddle might not have full motion back and forth.
    Servicefitter, I quoted your post with the intention of adding to a good post (yours). I did not mean to come across as correcting it. Believe me, I wasn't. If your post wasn't in response to mine, and correcting me, then I have misunderstood.

    I agree with both of your recent posts, and I have also seen this problem.

  8. #8
    Join Date
    Jan 2005
    Location
    Houston TX
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    LSullivan - As you have just drain the tower for maint. work I would suspect air in piping as it would only take a small amount of air especially with your piping configuration of an elbow directly after the flow switch. I don't know what the relationship is between your tower and chiller, but verify that there is no air pocket being circulated and the tower is at the proper level so no air gets sucked in through the base of the tower. GEO
    Once in a while everything falls into place and I am able to move forward, most of the time it just falls all over the place and I can't go anywhere-GEO

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