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  1. #1
    Join Date
    Jan 2013
    Location
    Frederick, MD
    Posts
    52

    Restriction from hell

    I love a good challenge and the chance to learn something new. But this one was ridiculous.

    With the correct charge weighed in the suction would pull into a vacuum after about 30 seconds and the head pressure would run about 270 psi.

    Now this is a new house. First time the A/C has been run.

    After over charging the system enough to get some suction pressure returning to the unit I was able to check the line temperatures inside and out. Only the usual 2-3 degree temperature difference. By this time the pressures were 650/125. So I did not let it run very long like that. Replaced the TXV at the indoor coil. While it was apart I blew through the line set with plenty of nitrogen. no problems. Put it back together....Same problem.... Next I ran a temporary new liquid line down the attic access hole and out a window to the outdoor unit....Same thing... By this time I'm getting pretty frustrated. Finally I pulled the evaporator and brought it outside. Sat it on top of the condenser and piped it in. Finally it worked. Now came the hard part. Replacing a 90 foot line set in a fully finished $500,000 house.

    After all day the new line set fixed the problem. How ever I was never able to locate a problem with the line set I pulled out.

    Just a side note. The line set I pulled out was aluminum.

  2. #2
    Join Date
    Nov 2004
    Location
    South Carolina
    Posts
    1,840
    aluminum?????????????????????????
    It is what it is unless I say differently !!!!

  3. #3
    Join Date
    Jan 2013
    Location
    Frederick, MD
    Posts
    52
    Yes Aluminum. My company gave it try. It was in an effort to cut cost. They have since changed their minds and we no longer use it.

  4. #4
    Join Date
    Nov 2004
    Location
    South Carolina
    Posts
    1,840
    sorry never heard of it in residential work
    It is what it is unless I say differently !!!!

  5. #5
    Join Date
    Jan 2013
    Location
    Frederick, MD
    Posts
    52
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  6. #6
    Join Date
    Jul 2009
    Location
    Columbia, MD
    Posts
    3,854
    someone forgot to take the plug out the lineset, or the coil

  7. #7
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    Quote Originally Posted by Frederick_Tech View Post
    Yes Aluminum. My company gave it try. It was in an effort to cut cost. They have since changed their minds and we no longer use it.
    Probably cost them >100x what they were trying to save on that job, lol.
    If more government is the answer, then it's a really stupid question.

  8. #8
    Join Date
    Jan 2010
    Posts
    6,232
    Who sells aluminum line sets ?

  9. #9
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    6,802
    Was there a kink in it somewhere, I can see where aluminum would be easy to kink.

  10. #10
    Join Date
    Nov 2006
    Location
    Athens, Ohio
    Posts
    1,772
    How do you connect and aluminum line set? Can you braze it?

  11. #11
    Join Date
    May 2011
    Location
    Western, KY
    Posts
    3,146
    Also, I would be interested in the method used to seal the connections at the coils(what material was the aluminum joined to at coils) and the splice since it was 90'.

  12. #12
    Join Date
    Mar 2009
    Location
    Mid-Mo
    Posts
    3,595
    Did it have a copper coated stubs on the ends? Not too uncommon to have copper coated steel on bigger stuff....

  13. #13
    Was the replacement line set the same size? Also was the length and lift of the line set within specifications? I'm not seeing how the line set was a problem no matter the material if it had good flow through it with nitrogen. That's why I'm wondering if any sizing or routing was done differently with the line set. 90 feet is a good haul and units like trane 20i's are real funny about that length and lift

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