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  1. #1

    suction line sizing

    Would someone be kind enough to answer question ...I am having a 5 ton coil R22 aprox. 57 feet from condenser to coil.. Condenser is ground level coil is 20 feet higher ... What is prefered diameter of suction line ..7/8 or
    1- 1/8 ?? Is there an advantage to go next size higher or not.. Some manuals list 7/8 as minimum ...others as 1 1/8. Your thoughts Please?
    Thanks

  2. #2
    Join Date
    Jan 2007
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    N.E. Ok.
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    1,359
    It will be determined by the mfg. and listed in the install manual.
    If curious you may be able to find the manual on the mfg. web site.

  3. #3
    Join Date
    Jun 2009
    Location
    Albuquerque NM
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    2,484
    Is this a heat pump or straight AC? On heat pumps, you may need to worry about maintaining the sufficient velocity in the 20 rise section, to insure oil return to the compressor. Sometimes, they'll use a smaller size on the vertical than on the horizontal. This is a compromise to maintain the velocity while allowing the remainder of the line to be larger for a long run.

    I ruled out on contractor because he wanted to use a 7/8 line on my 2.5t HP. The manufacurer allowed 3/4 or 7/8, but with the 7/8, the velocity in the vertical section would have fallen below the minimum specified by the manufacturer.

  4. #4
    Join Date
    Aug 2007
    Location
    Oregon
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    226
    Traps, I would make sure you have traps put on for proper oil return

  5. #5
    Join Date
    Jun 2006
    Posts
    1,105
    Different refrigerants have different requirements based upon flow velocities, no answer possible.

    Different brands and types have different requirements, no answer possible.

    When the evaporator is above the condensing unit DO NOT use oil traps, they are not required and increase losses.

    An inverted trap SHOULD be at the evaporator that routes it 1 or 2 inches above the top row of tubes of the evap.

    As far as suction piping goes, 57 feet may SOUND like a good number, however there is a term called EFFECTIVE piping length.

    As a general rule, problems can begin to exist after 50 feet and one should never reach beyond 150' of effective length.

    In other words, no one here can actually answer your question because we can not see it. General answers are not going to help you much since it may or may not apply.

  6. #6
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
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    4,906
    Quote Originally Posted by idontgetit View Post
    Different refrigerants have different requirements based upon flow velocities, no answer possible.

    Different brands and types have different requirements, no answer possible.

    When the evaporator is above the condensing unit DO NOT use oil traps, they are not required and increase losses.

    An inverted trap SHOULD be at the evaporator that routes it 1 or 2 inches above the top row of tubes of the evap.

    As far as suction piping goes, 57 feet may SOUND like a good number, however there is a term called EFFECTIVE piping length.

    As a general rule, problems can begin to exist after 50 feet and one should never reach beyond 150' of effective length.

    In other words, no one here can actually answer your question because we can not see it. General answers are not going to help you much since it may or may not apply.
    I agree.

    Traps are used to keep oil in the compressor, when a compressor is above the coil.

    An inverted trap at a coil prevents all the oil/liquid in the entire system from draining down to the compressor. This prevents the compressor from having to fight against this heavy load of startup. This is used when the coil is above the condensor.


    OP:

    Your putting the cart before the horse. Find your manufacturer FIRST, then look at what is required, via the manufacturer.

    For example. (working off of memory, don't quote my numbers, only ment to prove a point)

    If I were to install a carrier 14 seer heatpump, 410a, 5 ton, 50 ft completely horizontal lineset, according to carrier's documentation I'd probably loose about 6% CAPACITY (not efficiency) with 7/8.

    If I were looking at the exact same everything, but with goodman, their chart would claim 10%.
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  7. #7
    Join Date
    Dec 2004
    Location
    newton,mass.
    Posts
    6,109
    Two things ... how's about listening to the guy that is actually looking right at the job ... don't think you trust him then get someone else (or more) to look at it.

    Second thing ... some of the info posted is above wrong, I'm not going to say what's wrong as you may be a guy (home owner) doing the job (or attempting to) ... how's about just getting the job done right by someone who knows how.


    .
    "Nothing else can poison our culture, corrupt our society or ruin the character of our people like unearned money or unearned opportunity." -- James R. Cook

    "Fooling around with alternating current is just a waste of time. Nobody will use it, ever." Thomas Edison, 1889.

  8. #8
    Join Date
    Jun 2005
    Location
    Winston-Salem NC
    Posts
    1,133
    If I have a question about line sizing, I take a few measurements and call the manufacturer's tech support number, before I start buying equipment.

  9. #9
    Join Date
    Dec 2005
    Posts
    114
    The poster didn't say heat pump. He did say R-22... hmmmmm....In this day and age?
    Bob O. 84,Pa.

  10. #10
    Join Date
    Mar 2011
    Location
    California
    Posts
    16
    1 1/8

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