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Old chiller, new controller

Discussion in 'Commercial' started by otto, Aug 10, 2013.

  1. flange

    flange Act like you care and do SOMETHING!!

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  2. otto

    otto Bakery Chef

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    Well, how did I wire that. That can be a lot of explaining over a chat thread. First you need to study the original wiring diagram and understand its sequence of operation. By saying "four compressors with two unloaders makes six stages" that tells me you don't fully comprehend the staging of the unit. It is actually eight stages. Using the L series of the T775 will give you a digital PID "loop". So it's not always just either on or off at setpoint but uses the setpoint as a target to stage up or down in the throttle range.
     
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  3. otto

    otto Bakery Chef

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    Let's look at the original staging. When the chiller is set for 1-3-2-4 staging. Compressors 1 & 3 have unloaders.

    Stage 1: #1 unloaded
    Stage 2: #1 unloaded, #3 unloaded
    Stage 3: #1 unloaded, #3 unloaded, #2 on
    Stage 4: #1 loaded, #2 off, #3 unloaded
    Stage 5: #1 loaded, #2 on, #3 unloaded
    Stage 6: #1 loaded, #2 off, #3 unloaded, #4 on
    Stage 7: #1 loaded, #2 on, #3 loaded, #4 off
    Stage 8: #1 on loaded, #2 on, #3 loaded, #4 on

    The eight stages are a different combination of compressors coming on or off and loaded or unloaded. I may be mistaken on some of the sequencing there but the concept is displayed in the staging outlined above.

    You need to rewire the controller relays exactly the same way the relays on the old controller are wired. Follow the original diagram and wire them as it says. This is a project for a tech that is very good with complicated diagrams. It will test your patience so don't be in a rush. You will have to fit more than one wire into a relay terminal strip so you need to use 18 gauge wire, no bigger or they won't fit into the terminal. I may have used 16 gauge stranded but it made the job more difficult.
     
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  4. otto

    otto Bakery Chef

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    Looked back. I did use the original 16 gauge wire. It can be done. twist and solder the stranded wire might make it easier. Not too much solder, just enough to make the wire end rigid.
     
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  5. otto

    otto Bakery Chef

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    More later if needed. Time to go to work.
     
  6. JD Lambert’s

    JD Lambert’s New Member

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    Thank for your help
     
  7. otto

    otto Bakery Chef

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    Glad to help. It will seem a bit overwhelming at first but it can be done. Those are great chillers and it's nice to see they're being repaired rather than going to the scrap heap.
     
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  8. otto

    otto Bakery Chef

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    I also have pictures of the original wiring diagrams on this thread.
     
  9. otto

    otto Bakery Chef

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    This shows the capacity control steps, I was wrong about compressors on & off.
    See the cylinder count. 4 is unloaded, 6 is loaded.

    Capacity Control.PNG
     
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  10. frozensolid

    frozensolid Psychologist's Dream

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    Otto you would make a good controls guy. It easier on the back too.
     
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  11. JD Lambert’s

    JD Lambert’s New Member

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    Yep I get the stages of this chiller and how T775L stages up or down to keep the temperature close to what the sensor wants to be or the set points
     
  12. JD Lambert’s

    JD Lambert’s New Member

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    I agree with you there Otto
     
  13. flange

    flange Act like you care and do SOMETHING!!

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    bok bok bok bok bergerk!
     
  14. HMD

    HMD does it matter?

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    drinking thread is 2 threads below this one
     
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  15. otto

    otto Bakery Chef

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  16. flange

    flange Act like you care and do SOMETHING!!

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    not during the week these days. crazy busy right now and vacation next Saturday need to stay focused.
     
    otto likes this.
  17. knave

    knave Undeterred

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    Out for a rip
    Bergeerk.
     
  18. LemonWizard

    LemonWizard Blinky Lights Wizard

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  19. pintofstout

    pintofstout New Member

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    [​IMG]

    I pretty much abandoned cosmetics on this one, packed the wires together and figured I'd fix it later. Never did.

    It's actuality a quite simple project once you hit a stride, but i had to stare at it for a little bit first. Mine had a schematic right there on the panel.

    Also switched it over to 422D. Can't really get it to stage perfectly. What kinda control band did you use Otto?


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