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  1. #14
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    *if lineset* Darn autocorrect.

  2. #15
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    Quote Originally Posted by raulsteichen View Post
    I came across this diagram in the Goodman installation manual when we were putting in a HP unit. The boss said not to worry about it, we don't use those anymore. Then why is it in the manual? The install we're working on right now has a 6 foot elevation rise from the A-coil to the compressor. Diagram says we need one....boss says no. Who's right?Attachment 802104

    We've never used one on any install. Manual doesn't say how to make one if I did. Like what sort of dimensions would it have?
    Was never needed on any R22 system with a suction velocity over 900 FPM. Not needed for an R410A system if velocity is over 1200 FPM.
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  3. #16
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    Quote Originally Posted by beenthere View Post
    Was never needed on any R22 system with a suction velocity over 900 FPM. Not needed for an R410A system if velocity is over 1200 FPM.
    how do you measure and verify that?

  4. #17
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    Quote Originally Posted by HVAC_Marc View Post
    how do you measure and verify that?
    A good piping chart will tell you the velocity of the suction line. Verification not needed, as the manufacturers have tested their equipment and made the charts and or software. Trane has a good software program. However, I don't have it.

    R22, 3 ton unit with a 5/8" suction line, velocity of 3095FPM, and a 12.6PSIG pressure loss per 100 foot of line, and 5454 BTU capacity loss per 100 foot. With a 3/4" suction line, 2072FPM, and a 4.8 PSIG pressure loss per 100 foot, and a capacity loss of 2068 BTUs per 100 foot. With a 7/8" suction line, 1492FPM, and a pressure loss of 2.2 PSIG per 100 foot, and a capacity loss of 936 BTUS per 100 foot of suction line.

    Thats from a York piping chart.
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  6. #18
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    Thanks, I appreciate that. I dont run into it (ever).

    My concern would be as the compressor ages and it falls outside of the known specs, the lack of the trap will cause (very) premature failure.

  7. #19
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    Quote Originally Posted by HVAC_Marc View Post
    Thanks, I appreciate that. I dont run into it (ever).

    My concern would be as the compressor ages and it falls outside of the known specs, the lack of the trap will cause (very) premature failure.
    A trap in the circumstance you describe would do more harm than good. Oil traps are a restriction. They increase TEL of a line.

    If someone is worried about a evap coil being below the condenser. The trap near the condenser should be an inverted trap.
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  8. #20
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    Quote Originally Posted by beenthere View Post
    A trap in the circumstance you describe would do more harm than good. Oil traps are a restriction. They increase TEL of a line.

    If someone is worried about a evap coil being below the condenser. The trap near the condenser should be an inverted trap.
    I didnt describe it, the OP/OEM did. I realize they are a restriction and add to TEL. It's no different from plumbing or gas line sizing. According to the OP the drop is 6 feet. The OEM says anything more than 4 needs a trap (someplace). Based upon the instructions, it requires a trap (someplace).

  9. #21
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    Quote Originally Posted by beenthere View Post
    A trap in the circumstance you describe would do more harm than good. Oil traps are a restriction. They increase TEL of a line.

    If someone is worried about a evap coil being below the condenser. The trap near the condenser should be an inverted trap.
    Pretty much like how most linesets are run anyways like I said

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  11. #22
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    Quote Originally Posted by HVAC_Marc View Post
    I didnt describe it, the OP/OEM did. I realize they are a restriction and add to TEL. It's no different from plumbing or gas line sizing. According to the OP the drop is 6 feet. The OEM says anything more than 4 needs a trap (someplace). Based upon the instructions, it requires a trap (someplace).
    OEMs said a lot about R410A and POE oil. It wasn't true either.
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  12. #23
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    Thanks for all the discussion guys. I think I'll skip the trap now. Both to please the boss, and because according to those calculations above, it should be fine without. The unit is 4 ton with 7/8" line. So the velocity should be way over the under 1000 velocity mentioned as needed. Maybe later when I more fully understand what they do I'll consider adding them when appropriate. Although Goodman's diagram does recommend it... Hmmm...

  13. #24
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    4 ton R410A, 7/8" suction line, velocity 1395, Pressure drop 2.6 PSIG per 100 foot, capacity loss 936 BTUs per 100 foot.
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  14. #25
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    Thread Starter
    R22

  15. #26
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    Quote Originally Posted by raulsteichen View Post
    R22
    7/8" suction line, 1990FPM, 3.6PSIG pressure drop per 100 foot, and 2105 BTUs of capacity loss per 100 foot.
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