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  1. #1
    Join Date
    May 2008
    Posts
    7

    Question charging split system

    is it a better practice to charge using the sight glass or checking super heat/ subcooling? i have a five to carrier that took 30 lbs of r22 and the sight glass still flashes.is this normal?

  2. #2
    Join Date
    May 2006
    Location
    east central indiana
    Posts
    1,117
    Ouch!
    This space for rent.

  3. #3
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,704
    Thats normal for 250 to 300' line sets on 5 ton heat pumps.

    Instead of looking at the sight glass so much. Check the indoor temp both drybuld, and wet, and the outdoor dry bulb. Find out what type of metering device it uses.
    The charge by either Sh, and or SC.
    Is this a new install, or a recharge after a refrigerant conponet change out.

    Not allowed to get too technical. But good chance that compresor is drowning from liquid flood back.
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  4. #4
    Join Date
    Mar 2008
    Location
    chambersburg pa
    Posts
    47
    it is better to check your sh/sc depending on the system you have. the sight glass should be for checking for moisture only.

  5. #5
    Join Date
    May 2006
    Location
    east central indiana
    Posts
    1,117
    Originally posted by beenthere
    Thats normal for 250 to 300' line sets on 5 ton heat pumps.
    Good Morning, Mr. Beenthere.
    I'm glad you touched on that, I was thinking, "gee that system must have one heckuva lineset to take that much refrigerant?" I wonder if that 30lbs is including, or in addition to the factory charge?
    I have a five ton Carrier system (10 SEER) with a TXV and an accumulator and about a 100' lineset. No sightglass though. It takes 23lbs. from deep vacuum to full charge.

    You see, I'm always a little afraid to say anything truly useful in response to a question like this in the open forums here.
    This space for rent.

  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,704
    Line set length changes charge amounts quickly.
    I got split 7.5 ton HP's with correct charges from 19lbs. to in excess of 30lbs.
    And some 10 ton split HP's that take less then 30lbs.
    All depends on the installed application.
    Some new 13 SEER 5 ton R22 A/C units come with 15+ pounds factory charge, and thats only for a 15' line set.


    So I'll wait till he says its a 10' line set, and then punce on him.

    You are correct, it takes a thick skin to post on here sometimes.
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  7. #7
    Join Date
    Nov 2005
    Location
    Shreveport, Louisiana
    Posts
    2,329
    Quote Originally Posted by tirednow View Post
    it is better to check your sh/sc depending on the system you have. the sight glass should be for checking for moisture only.

    Ditto Leave the sight glass alone.
    Long line sets if you charge until the site glass is clear you WILL be overcharged.
    UA Local 141

  8. #8
    Join Date
    Nov 2005
    Location
    Shreveport, Louisiana
    Posts
    2,329
    Quote Originally Posted by horsewhipp View Post
    is it a better practice to charge using the sight glass or checking super heat/ subcooling? i have a five to carrier that took 30 lbs of r22 and the sight glass still flashes.is this normal?

    Is this a trick question...
    UA Local 141

  9. #9
    Join Date
    Jun 2003
    Location
    Florida
    Posts
    9,548
    So you guys run 300ft linesets??? Hmmm....
    If everything was always done "by the book"....the book would never change.

  10. #10
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,704
    300 foot was an exaggeration. But not by much.

    As a rule, if I think a line set is a little long, I get the manufacturer involved.
    I have line sets exceeding 200 foot. Factory engineers sized it though. Keeps the factory warranty in tack in they design and approve.

    One, we had to use a 7.5 ton condenser to get 5 tons of A/C. Ok, I think they said it gets 5.25 tons hooked to its 7.5 ton nominal rated evap coil.


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  11. #11
    Join Date
    Dec 2007
    Location
    oklahoma city U.S.A.
    Posts
    224

    Smile I must be newschool

    I don't even use the sight glass. Just sh or sc depending on the meteoring device. They don't even use those on T.X.V. applications I don't think. I might be wrong.

  12. #12
    Join Date
    Jun 2007
    Location
    Greenville,North Carolina
    Posts
    1,903
    The only time that I have used sight glasses is when they are spec or when I have questions about moisture in a system.

  13. #13
    Join Date
    Dec 2004
    Location
    newton,mass.
    Posts
    6,109
    Umm... if you have a sight glass then it should be a txv system...and you can charge the system to a full sight glass without over charging...follow the chart for that system and all will be well. It also depends where the sight glass is located. We have piped in many systems with over two hundred feet of pipe runs. Also there is no mention of the line sizes, as you all know...that makes a difference.


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

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