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Thread: drain lines

  1. #1
    Join Date
    Aug 2011
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    27

    drain lines

    i had a drain that was on a hirozanl unit it had a pee trap that someone had made the blower motor was down stream of the evap coil the unit was a goodman ever thing looked level would not drain remove pee trap water ran out it was not double trap so why would nt drain

  2. #2
    Join Date
    Dec 2007
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    4,770
    read install instructions and it should become clear.
    The Food Stamp Program, administered by the U.S. Department of Agriculture, is proud to be distributing the greatest amount of free meals and stamps EVER.
    Meanwhile, the National Park Service, administered by the U.S. Department of the Interior, asks us to "Please Do Not Feed the Animals". Their stated reason for this policy "... the animals become dependent on handouts and will not learn to take care of themselves."
    from an excerpt by Paul Jacob in Sun City, AZ

  3. #3
    Join Date
    Oct 2009
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    Rhode Island
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    is the outlet of the p-trap lower than the inlet?

  4. #4
    Join Date
    Sep 2006
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    95
    Was the line level?

  5. #5
    Join Date
    Nov 2004
    Location
    Austin, TX
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    888
    I've seen newly installed systems that had the drain line going uphill.
    If you push down on the drain line it would drain.
    Sometimes the p-trap has a clog in it too.
    Too much glue can effectively narrow the drainpipe.


    Poor p-trap design can cause it to fail too.
    I've seen a vent installed between the p-trap and the coil. With a negative pressure drain, as you described, the vent will allow the blower to suck in air with enough pressure to stop the condensate from draining, just one continuous air dam until the blower shuts off.
    You can have a clean out at the top of the p-trap, the clean out must be capped for a negative pressure drain to operate. Without the cap the clean out turns into a vent with the previously described issue.
    “I am for doing good to the poor, but...I think the best way of doing good to the poor, is not making them easy in poverty, but leading or driving them out of it. I observed...that the more public provisions were made for the poor, the less they provided for themselves, and of course became poorer. And, on the contrary, the less was done for them, the more they did for themselves, and became richer.”
    ― Benjamin Franklin

  6. #6
    Join Date
    Aug 2011
    Location
    North West FL
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    97
    There is a certian amount of water held in or back by the trap. When you cut it out, there will be a small flow of water. Often if I have a clogged drain, it's because they put a trap in too far up line. I put them in at the outlet of the drain usually. Esp if it's a down flow unit. Also, did you put a level on it? Many times things "look" level or "feel" cool until you verify.

  7. #7
    Join Date
    Feb 2010
    Location
    Ontario Canada
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    1,341
    The drain line should be 3/4". The wier of the trap should be a min of 4". The line coming out of the trap should go into a tee with the top of this tee open to air. The line coming out of this tee should be sloped to a drain. If all conditions are met, it will drain.
    I like putting unions in, before and after trap to make cleaning the trap easy.
    Never give up; Never surrender!

  8. #8
    Join Date
    Mar 2011
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    11
    Iif the blower is before the coil (down stream ) and there was no vent tee before the trap you had a vapor lock. The air and water come out the some hole(drain line) when the air hits the water iin the trap it turns around and goes back in the drain hole and creates an air dam thus not allowing the water to drain.
    some manufacturers say if you have a 2vapor inch trap no vent tee is needed however that is for a system wiith perfect static pressures. I always put a vent before the trap and leave cap off on positive pressure drains and cap it on negative pressure drains

  9. #9
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
    Posts
    5,337
    Quote Originally Posted by brian.nc View Post
    Iif the blower is before the coil (down stream ) and there was no vent tee before the trap you had a vapor lock. The air and water come out the some hole(drain line) when the air hits the water iin the trap it turns around and goes back in the drain hole and creates an air dam thus not allowing the water to drain.
    some manufacturers say if you have a 2vapor inch trap no vent tee is needed however that is for a system wiith perfect static pressures. I always put a vent before the trap and leave cap off on positive pressure drains and cap it on negative pressure drains
    Brian, if your installing a vent BEFORE the trap, then your effectively negating any benefit of the trap.

    A single trap will not create vapor lock. It would have to be double trapped.
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  10. #10
    Join Date
    Mar 2011
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    11
    Code dictates we put in a trap. They say it prevents radon from entering the house.
    I would prefer no trap.

  11. #11
    Join Date
    Aug 2009
    Location
    Jurupa Valley, CA
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    1,787
    Quote Originally Posted by brian.nc View Post
    Code dictates we put in a trap. They say it prevents radon from entering the house.
    I would prefer no trap.
    Right. If you have a vent on the unit side of the trap, attached to the suction side of the blower, it is pulling air in through that vent, right into the unit, and spreading throughout the house. The trap is there to keep the mech room air and the conditioned air separate, while still allowing condensate to flow out. The vent should be on the side of the trap AWAY from the air handler.

    The only reason to even have a tee between the unit and the trap, is for cleaning out the trap... and after cleaned, it should be sealed with a cap.

  12. #12
    Join Date
    Mar 2011
    Posts
    11
    Please explian why a vent is not needed before trap with a gas furnace below the e-coil.
    I don't want to do this wrong

  13. #13
    Join Date
    Aug 2009
    Location
    Jurupa Valley, CA
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    1,787
    As previously mentioned, a trap is there to keep a slug of water to separate the air in the unit, and the air in the space. If you have a vent in between the trap (the slug of water), and the unit, then the slug of water is doing nothing to separate anything. There's not really a reason for a vent downstream of the trap, aside for a path for flow out of the unit if the drain becomes plugged, so it doesn't back up into the unit.

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