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Condenser, lineset, coil

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I am nearing completion of a Unico installation. I did the ductwork DIY in a very tight crawlspace (I doubt a pro would have done it). I intend to bring in a pro to connect the refrigeration stuff. The coil has 3/8" liquid line and 7/8" suction line. I would like to purchase the condenser and lineset and have it on site for the pro. Do I need to purchase a condenser that has 3/8, 7/8 connections? I see some have 3/8, 3/4. Thanks

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  • dko
    dko Member Posts: 642
    edited March 2023
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    The best resource you have is to read the manual of the condenser you are looking to purchase. It will tell you the recommended size for your application.

    Example page from a Bosch unit below:



    But for shorter lengths... 3/4 or 7/8 won't make too much of a difference.
    jhewings
  • ratio
    ratio Member Posts: 3,696
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    What is the model number of the condenser & evap? Got a guesstimate of the vertical separation (I'll assume evap over condenser) and total lineset length?

    IDK how it is where you're at, but around here it's fairly difficult for homeowners to purchase refrigeration equip, in fact the last time I sent someone to pick up a simple capacitor I had to get on the phone and argue with the counter guy about it!

    HVACNUT
  • jhewings
    jhewings Member Posts: 139
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    I can run the 7/8 for the lineset ( less than 25ft). I guess my real question is can I reduce to 3/4 at the condenser? Or should I be looking for a condenser than is 7/8? This for 2 Tons. Thanks
  • jhewings
    jhewings Member Posts: 139
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    M2430CL1-E - UNICO MODULE, REFRIGERANT COIL (6 ROW) (HP). Condenser to be determined. Unico says use any major 3rd party condenser. Thanks
  • dko
    dko Member Posts: 642
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    jhewings said:

    M2430CL1-E - UNICO MODULE, REFRIGERANT COIL (6 ROW) (HP). Condenser to be determined. Unico says use any major 3rd party condenser. Thanks

    Use the condenser's recommended line set size and reduce at the evaporator. The evaporator connector is sized larger to accommodate the higher end of it's capacity.
    jhewingsratio
  • jhewings
    jhewings Member Posts: 139
    edited March 2023
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    Thanks
  • ratio
    ratio Member Posts: 3,696
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    At 25', ⅞ will be way oversized for 2 tons. You're probably looking at ⅝, but check the paperworks.
    jhewingsEBEBRATT-Ed
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,829
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    Agree. 7/8 is usually used for 3 tons. Too large for two tons you have to consider oil return not just refrigerant capacity
    jhewings
  • HVACNUT
    HVACNUT Member Posts: 5,887
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    I would find a contractor who agrees to do what you want before you buy any equipment, or it might wind up being a very bad DIY.
    ratiojhewings
  • ratio
    ratio Member Posts: 3,696
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    @HVACNUT gave you some good advice. The proportion of hacks vs skilled mechanics who will do what you want doesn't inspire a lot of confidence that you'll get a well-performing system; finding the right person is critical.
    jhewings
  • clammy
    clammy Member Posts: 3,113
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    A 2 ton system is usually 3/4 or 5/8 suction line .Depending upon both the coil connection and condenser connection . Usually at a mim I will use the condenser connection size being it usually sized for proper run sizing and running a larger suction may effect ref oil return to the condenser . As for a liquid line 3/8 is standard on most residential units but at such a small tonnage for what it’s worth a 1/4 liquid line would suffice it would also slightly reduce the charge . In a effort to reduce the refrigerant charge over what’s included in the condenser usually 15 ft . A word of advise be sure your pro brazes your line set while purging w nitrogen and that the liquid line dryer is installed at the air handler not outdoors . Also insist that a min 1 hours pressure test is performed and that your system is properly vacuum and properly charged using the sub cooling required at the condenser for proper function . Also as a side note make sure what ever thermostat you are using is equipped w anti short cycling or just have your contractor install a time delay relay in the condensate . As be a little nuts I would also recommend a voltage surge protect for ur air handler and be sure to install a fuse able disconnect for your outdoor unit most do not but there’s a reason for it aside from protecting your compressor from over drawing but also protect from over draw when condenser contactors are pitted and dirty . Cheap insurance in the long term . Peace and good luck clammy
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
    jhewings