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  1. #1
    Join Date
    Jul 2007
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    New Jersey
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    Line size on split question

    I have to change a compressor on a Carrier split system unit over in our other mill.

    I ordered and recieve the replacement compressor and FD. The suction line is7/8.

    Im coming from my other mill and would have to plan out and bring and couplings or pipe that i would need.

    So i called the salesman to get the info for correct line size since I didnt order it myself, the director at the other plant did it. So i dont have the model # info.

    So Carrier says it a 7/8 suction, but they changed the specs on it and it really needs a 1 1/8 line.

    This throws a monkey wrench in my whole idea of a compressor change out. lol..Its the difference of an hour or 2, compared to a days work.

    The lines go up 20' , through a concrete wall, straight about 10', and finally elbows about 3-4' into evap.

    The old compressor ran for years with the 7/8 in there. The compressor failed mechanically. It runs, but just free spins inside. (If that helps what the possible failure could've been.)

    What should I do?

    a. Leave it as 7/8?

    b. Do the 1 1/8 run?

    c. Tell the plant manager what his options are, pros and cons (which im not even sure about besides the copper he has to buy) and ask what he opts for?

    Its the same company I work for , just a different plant. So Im already on the clock so labor isnt needed to quote. Just a heck of alot of overtime.
    “If I have seen further than others, it is by standing upon the shoulders of giants.” ~ Sir Isaac Newton


    I'm learning all the time, the tombstone will be my diploma!!!


    Did you ever stop to think, and forget to start again?

  2. #2
    Join Date
    May 2003
    Location
    Utah
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    743
    Not a lot to go on here.

    You might want to look at the system capacity and use a pipe sizing program to see what the suction line size ought to be, based on the equivalent length of pipe you've got in the system.

    If the 7/8" turns out to be undersized compared to what the pipe sizing program recommends, then present the issue to the customer with the pros/cons of doing the job correctly. The only "con" is that it's going to cost him to do the job correctly.

    If he declines to do the job correctly, make sure you get his signature that shows he knew what you were recommending, and declined.

  3. #3
    Join Date
    Jun 2009
    Location
    Albuquerque NM
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    I'm not a pro, but if I was, I'd be thinking about the minimum suction velocity in the 20' vertical section for proper oil return.

    And ... if a pro said he would use 7/8 in the vertical and 1 1/8 in the horizontal I'd say that sounds pretty clever.

    Just sayin' ...

  4. #4
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    May 2003
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    Utah
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    Quote Originally Posted by Tommy1010 View Post
    The lines go up 20' , through a concrete wall, straight about 10', and finally elbows about 3-4' into evap.
    If I read this correctly the evaporator is above the condensing unit.

    Hence, there is no vertical suction riser. While maintaining that critical balance between minimum velocity and a minimal pressure drop in the suction piping is always recommended, oil return on a line that naturally drains downward 20' to the compressor shouldn't be an issue.

  5. #5
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    Jun 2009
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    Quote Originally Posted by bunny View Post
    If I read this correctly the evaporator is above the condensing unit.

    Hence, there is no vertical suction riser. While maintaining that critical balance between minimum velocity and a minimal pressure drop in the suction piping is always recommended, oil return on a line that naturally drains downward 20' to the compressor shouldn't be an issue.
    Ah, I missed that.

  6. #6
    Join Date
    Jul 2007
    Location
    Virginia
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    Quote Originally Posted by Tommy1010 View Post

    What should I do?

    a. Leave it as 7/8?

    b. Do the 1 1/8 run?

    c. Tell the plant manager what his options are, pros and cons (which im not even sure about besides the copper he has to buy) and ask what he opts for?
    I’m assuming this is a single stage, straight A/C, 410A system?

    Carrier says that systems of 3 1/2 - 5 tons can use both 7/8” and 1 1/8” suction lines.

    The 7/8” line can be used on the 3 1/2 and 4 tons units without any capacity loss as long as the TEL doesn’t exceed 80 feet.

    If the 7/8” line is used on the 5 tons system, you would only have a 1% capacity loss on lengths up to 80 feet.

    I would just use the 7/8” on your system seeing as it is only about 40 feet.

    If you want to show the plant manager Carrier’s Long LineSet application that states what I said above, let me know, and I will email it to you.
    Instead of learning the tricks of the trade, learn the trade.

  7. #7
    Join Date
    Jul 2007
    Location
    New Jersey
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    Quote Originally Posted by rundawg View Post
    I’m assuming this is a single stage, straight A/C, 410A system?

    Carrier says that systems of 3 1/2 - 5 tons can use both 7/8” and 1 1/8” suction lines.

    The 7/8” line can be used on the 3 1/2 and 4 tons units without any capacity loss as long as the TEL doesn’t exceed 80 feet.

    If the 7/8” line is used on the 5 tons system, you would only have a 1% capacity loss on lengths up to 80 feet.

    I would just use the 7/8” on your system seeing as it is only about 40 feet.

    If you want to show the plant manager Carrier’s Long LineSet application that states what I said above, let me know, and I will email it to you.
    Is it recent? cause the rep I spoke wit said this today...but ofcourse he's probably a desk clerk.

    Its 15 - 20' at most of a rise, through wall..20' to evap..

    NO ITS A 22 system

    Obviously im sayin it backwards as far as flow goes but from ground up regarding piping thats my case.

    The salesman looked at a chart and verified that he agreed with carrier, it should be 1 1/8 though..

    discharge is 1/2, and LL is 3/8.

    CmON DAWG, lemme know.
    “If I have seen further than others, it is by standing upon the shoulders of giants.” ~ Sir Isaac Newton


    I'm learning all the time, the tombstone will be my diploma!!!


    Did you ever stop to think, and forget to start again?

  8. #8
    Join Date
    Jul 2005
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    5,576
    Why did you post this in the open forum?

  9. #9
    Join Date
    Jul 2007
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    New Jersey
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    Quote Originally Posted by hvacrmedic View Post
    Why did you post this in the open forum?

    Honestly...cuz i dont know where to consider the PRO FORUM anymore!!!

    People are all over since this change. Its also why I'm not on as much anymore.

    I dont know WHERE TO GO LIKE I DID WHEN IT WAS ...LIKE IT WAS. "PRO....TECH" was on my desk top. So I feel lost with this big change man.
    “If I have seen further than others, it is by standing upon the shoulders of giants.” ~ Sir Isaac Newton


    I'm learning all the time, the tombstone will be my diploma!!!


    Did you ever stop to think, and forget to start again?

  10. #10
    Join Date
    Oct 2010
    Location
    AZ
    Posts
    647
    How big is the unit?

    What is the design condensing temperature?

  11. #11
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    Quote Originally Posted by Tommy1010 View Post
    NO ITS A 22 system
    The capacity losses with R22 are different. It will be later today, but I will see if I can find that manual and email it to you.
    Instead of learning the tricks of the trade, learn the trade.

  12. #12
    Join Date
    Dec 2002
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    SouthEast NC ICW & Piedmont Foothills
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    7,635
    Tommy, check that aol account
    It`s better to be silent and thought the fool; than speak and remove all doubt.

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