AC condensate into DWV wye?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by chassis, Sep 6, 2011.

  1. chassis

    chassis Engineer

    Messages:
    339
    Location:
    SE Pennsylvania
    Hello all,

    I searched this site on this question, and I think (hope) what I want to do is OK.

    Presently my ac condensate line is plumbed via 1/2" PVC to a vertical, open (to the air) drain pipe in the basement concrete floor. There is an "air gap" and the condensate line is not solidly connected to the floor drain pipe. The vertical floor drain pipe is presently open to the air, and is not sealed.

    I want to install a new utility sink in the basement, and plumb the sink drain to the pipe which is used by the ac condensate. I propose to use a DWV wye, with the vertical (straight) leg for the utility sink drain, and the wye leg for the ac condensate. The 1/2" PVC condensate line would be run loosely into the wye, therefore maintaining the air gap with no solid connection.

    Is this OK? If not, how would I plumb the two drains properly, utilizing a shared drain pipe in the floor? Thanks.
  2. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    If I understand your description, you would send the condensate in behind the sink trap. That won't do, because at a minimum you would have an open sewer connection, and possilby would actually draw sewer gas back into the air conditioner. You need to have the air gap somewhere, but you also need to be going into a trap.
  3. mrmedic

    mrmedic Junior Member

    Messages:
    57
    Location:
    Delaware
    My condensate drain just runs into my utility sink just like you would run a washer drain hose.
  4. cwhyu2

    cwhyu2 Consultant

    Messages:
    1,347
    Location:
    Cincinnati OH
    That is okay as long as it does penetrate the flood level rim of the fixture it is wasting into.
    Also called a safe waste.
  5. Jerome2877

    Jerome2877 In the Trades

    Messages:
    397
    Location:
    BC
    Are you sure this drain runs to the sewer? It could be going into the storm drains. If it is sewer then it would have a trap under the slab. Your proposal would not meet any codes.
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,811
    Location:
    Cave Creek, Arizona
    If that "riser" has a trap under the floor, your proposal seems to be okay, assuming we actually understand what you intend to do.
  7. chassis

    chassis Engineer

    Messages:
    339
    Location:
    SE Pennsylvania
    Guys, thanks for the input. I'm pretty sure it has a trap in the floor. I have other floor drains in the basement, and periodically I need to add water to them to replenish the water that has evaporated from them. Is there a way I can verify there is a trap connected to the riser?

    I plan to install a trap on the utility sink. The ac condensate line would flow into the riser by means of the wye. From the condensate line perspective, nothing changes. It has a trap, if one exists in the slab, which I think it does. Therefore the utility sink would have two traps in series - the sink trap and the trap in the slab.
  8. Jerome2877

    Jerome2877 In the Trades

    Messages:
    397
    Location:
    BC
    Nope, you can't have traps in series. Floor drains are there for a reason and it probably isn't vented. If you really wanted to do this though I would suggest jackhammering the slab and removing the trap. Then connect to the drain bring it up and then vent it. The condensate drain would probably be too low to use the sink drain so maybe use a pump and plumb it like a dishwasher with an air gap or find another place to drain it.
  9. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,811
    Location:
    Cave Creek, Arizona
    Actually, you can have as many traps "in a series" as you want to, as long as EACH one has a vent, which would be the case here with an open riser for the A/C condensate.
  10. BobL43

    BobL43 DIY Senior Member

    Messages:
    1,793
    Location:
    Long Island, NY
    Is it against code or good paractice to have an air handler in the center of an attic which has a ptrap at its condensate outlet to drain into a 3 inch main stack/vent in the attic? The nearest end (gable) wall is 30 feet away, but the stack is about 12 feet away from the air handler?:eek:
  11. bluebinky

    bluebinky Member

    Messages:
    405
    Location:
    Santa Clara, CA
    My understanding (of the UPC that is) is that you cannot run a drain into a vent -- even a condensate drain. That said, apparently, it is common practice in some areas to tie into an attic vent...

    Between the AC drain and sewer, there needs to be an air gap (or possibly air break). The gap also acts as a vent allowing for the second (sewer-side) trap as well. Before the gap is considered to not be plumbing, but rather part of the AC -- and the installation is governed by the AC equipment instructions and local "mechanical" code (someone please correct me if I'm wrong). After the gap is, of course, "plumbing". There must be some way to keep the sewer-side trap filled when the AC is not in use. That is hard to do in an attic...

    I vote for ending the existing drain above the laundry tub rim.
    Last edited: Sep 8, 2011
  12. BobL43

    BobL43 DIY Senior Member

    Messages:
    1,793
    Location:
    Long Island, NY
    When the AC installer put my system in in 1987, he tied the condensate into my vent line, and i did not know it. all these years, we never smelled anything in the house. he did not install any type of trap at all. I recently went up ther and saw this, and I at least put up a trap there (made up of 4 45 degree elbows and 2 unions all PVC). I guess there is enough draft in the stack and/or the condensate port is on the positive pressure side of the blower to not suck in any foul smells and blow them into the house. I'm going to re-do it anyhow and run the line from the air handler to the end wall to outside the house one day. We don't have city sewage systems here; all cesspools. I guess the house trap is working well:D . What a hack job he did on that, but the rest of the system is good. Still working (well) after 24 years. The trap did not freeze up and crack last winter, so I guess it dried out after the cooling season and before really getting too cold.
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