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  1. #1
    Join Date
    Jun 2008
    Location
    Southern,N.J
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    1

    Line set sizing?

    What affects or damage can occur when running smaller diameter lines for a discharge or suction line? I know deff higher head pressures. I'm new to the field experts please chime in..Also new to the site hello everyone..

  2. #2
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,793
    Lower capacity
    Lower efficiency
    Possible shortened compressor life.

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  3. #3
    Join Date
    Sep 2003
    Posts
    139
    If the suction line is too small, you may not get proper oil return to the compressor. You also can have a reduced capacity.

  4. #4
    Join Date
    Jan 2004
    Location
    PA
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    An undersize vapor line doesn't hurt oil return.
    Too large of a vapor line can.
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  5. #5
    Join Date
    Sep 2003
    Posts
    139
    WOW! I hope you don't do refrigeration! OOPS... Read it wrong Beenthere! Need to assure proper velocity Horizontal increase size, vertical decrease.
    Last edited by heatingairman; 07-06-2008 at 11:12 PM. Reason: Read wrong

  6. #6
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,793
    Both A/C and refrigeration.
    A vapor line 1 size undr will never hurt oil return.
    The next size up however can on installs with the condenser vertically above.

    Recommended min suction line velocity is 1000 FPM. I have vapor line sizing charts for unit that allow the vapor line to be sized for up to 3000 FPM.

    I don't have any that approve less then 800 FPM. And they don't want a vertical rise to the condenser.

    If you have line set sizing charts that allow 500FPM velocity in the vapor line, post them.
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  7. #7
    Join Date
    Sep 2003
    Posts
    139
    I don't think anyone will go out on a limb with 500fpm

  8. #8
    Join Date
    Apr 2007
    Posts
    6,285
    So is it safe to say it's a trade off of capacity for smaller sizes and velocity is not so much a concern or oil return......and the LL is way more important to capacity?

    Also how important are traps in vertical rises of 50+ ft? I might be subjecting myself to these before to long. Not sure if they even put traps in @ the recommended heights.....for oil return?

  9. #9
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,793
    Involved topic Jon.

    Within reason, you can compensate a little for a slightly smalled liquid line, more then a vapor line.

    Did you get that email I sent you. It has some line set sizing info in it.
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  10. #10
    Join Date
    Apr 2007
    Posts
    6,285
    I'll check....I didn't think this was the right forum to get to involved.


    was that just now or recently in the past?

  11. #11
    Join Date
    Sep 2003
    Posts
    139
    I sent yo an email too bigjon.

  12. #12
    Join Date
    Jan 2004
    Location
    PA
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    Within teh last few days..
    I don't remmember which.
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  13. #13
    Join Date
    Apr 2007
    Posts
    6,285
    i'll go back over I'm sure i got it.

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