Air conditioner condensation drain line

Discussion in 'The Okie Corral' started by SC Tiger, Sep 15, 2015.

  1. SC Tiger

    SC Tiger As God as my witness, I thought turkeys could fly.

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    My house has central air with the air handler under the house and a drain line running out to the foundation drain. However, something odd I noticed is that the drain line has a "p" trap in it made from PVC pipe elbows and straights.

    As I understand it "p" traps are to keep gasses from coming back up the drain. Is this necessary on an air conditioner drain line? If it is I believe they make PVC traps for a straight horizontal line (it has slope but you know what I mean) that are much simpler. But I am not sure it even needs this. I wonder if the fact that it goes to a closed foundation drain has something to do with it.

    If I need the trap this is what I plan to use:

    [​IMG]

    What started this is I noticed that this trap got clogged. I disassembled and cleaned the trap and it drains now but I am sure this will happen again if I don't find a better solution. Thanks in advance.
     
  2. Adjuster

    Adjuster

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    Not a single person does it but your a/c drain line should be flushed on a monthly basis same time you change/clean your filter. The drain line has a trap to prevent critters from entering. The trap isn't 100% necessary like a sink trap but most professional HVAC installers put in a trap.


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  3. SC Tiger

    SC Tiger As God as my witness, I thought turkeys could fly.

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    Makes sense. I'll leave it in - or build a new one. I also plan to put a cleanout port upstream of it so that when I bleach the line it will go in the trap as well.

    A newer unit probably wouldn't make this much water but IMO it would cost more to replace the unit than I would save in power right now.
     
    Last edited: Sep 15, 2015
  4. aircarver

    aircarver Descent Terminated Silver Member

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    I've seen a lot of drain lines that didn't bother with a trap. I have a lot of unhappy experience with lines that were clogged... (usually by bugs) :frown:

    The periodic flushing with a dilute clorox solution will make an unfriendly environment for bugs.

    I modify the line to the drain so I can put an air bottle on it to blow out the obstruction (skip the open to the air port, so the pressure goes down the line to the drain ...)
    This has sometimes had 'hilarious' results 'cuz one such 'blowout' caused mud to blow out of all the drains in the bathroom below ... causing a mess ... :sigh:
     
  5. IndyGunFreak

    IndyGunFreak

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    The answer is... it depends. If it ties into anything (ie, a stack line, etc.) then yes, absolutely. Assuming your plumbing is working properly, in this case it will stink to high heaven if you remove the trap. Quite often these condensate lines come down, and drop on top of a floor drain (which is trapped)... In this case, no it would not need to be trapped, because it doesn't actually tie into anything,

    It's hard to tell from your description exactly how yours is set up, but that's the best way I can explain it.
     
  6. John Rambo

    John Rambo Raven

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    Mine has one. I also have a cleaning port way upstream near the handler. It does clog (in Florida there is no way around it) and I have to stick a shop vac on the end of it and vacuum it out. The cleaning port has been a lifesaver for pouring bleach in. With the kinds of bugs we have down here I'm fine with having a trap there to keep who-knows-what out of the drain line. I vacuum it 2-4 times a year with the shop vac because it isn't pretty when it backs up and soaks the ceiling.
     
  7. SRS

    SRS

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    When I bought my house, I had no idea. I learned my lesson when I noticed water pooling on the basement floor. Now it gets flushed regularly.
     
  8. stopatrain

    stopatrain Lifetime Member

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    I put liquid plumber down my main drain Line several times a year. Never had it stop up.
     
  9. SC Tiger

    SC Tiger As God as my witness, I thought turkeys could fly.

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    My house has a french drain along the inside of the exterior walls, in the crawlspace. The drain plugs into that near the crawlspace door.

    What I am hearing is to leave the trap in. What I think I will do is replace the existing made-with-PVC-elbows trap with one like I pictured above, just downstream of a port that will allow me to clean it out and will allow any bleach I pour in to go into the trap. I may also put this closer to the end of the line (away from the AC unit) so that cleaning it will be easier and more convenient (which means I will do it more). A straight run from the pan to the trap also means I can snake that portion of the drain line out if needed.
     
  10. kiole

    kiole

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    Long term use of liquid drain unclogging chemicals is very hard on your pipes.

    What material is your drain lines made of?
     
  11. PBCounty

    PBCounty

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    Stick a shop vac hose on the exterior drain for about three seconds once a year and it should solve most of this clogging without getting too complicated.
     
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  12. IndyGunFreak

    IndyGunFreak

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    If the drain is flowing.. it's fine. If you read the directions on those bottles... They say to use the product, then flush the drain.. Naturally, they are assuming the product is going to work and clear the clog, so it's easy to flush. The problem is, when it doesn't clear the drain... now you have all that acid laying in the line and no way to flush it out.

    That's when the fun stuff happens.

    If the drain is flowing, you can use it and it won't hurt anything.... but it doesn't really do anything either, because it just runs from one end to the other.
     
  13. Dennis in MA

    Dennis in MA Get off my lawn

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    My old one had a loop in it as the trap. Then I got a humifaddider for the heat so they put a pump and dropped the waste into the sewer line. At least one trap.
     
  14. NDcent

    NDcent Socially Inept

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    I've got one in a rental that gets clogged up with buggers and snot like slim off the evaporator. Cleaning the coil now and then doesn't stop it, so I blow the drain out with a portable air tank once a year. No trap in it that I've noticed.
     
  15. stopatrain

    stopatrain Lifetime Member

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    PVC
     
  16. F106 Fan

    F106 Fan

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    Google is your friend: Search 'hvac p trap'



    Yes, you need a P trap...
     
  17. w30olds

    w30olds Me fail English? That's unpossible

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    It depends if the air handler is positive or negative pressure. The p-trap keeps water from being sucked back into the negative air handler and allows for proper draining. The positive doesn't require a trap usually because the air is pushing the condensate in a positive pressure. Hope this made sense.
     
  18. Arm America

    Arm America

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    Yep, you need the trap, otherwise your A-coil pan will not drain correctly causing it to overflow.
    If your A-coil is above your furnace or air handler and not trapped, the vacuum will prevent condensation
    from draining causing the pan to overflow and drip on the electrical connections in the furnace.
     
  19. Adjuster

    Adjuster

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    The guys with the shop vacs are doing it the correct way. Simply go outside and cup the nozzle of the vac hose over the drain line end. Form a good seal with your hand. Turn it on and you will suck out a bucket full of slime. The air pressure way works also but can get extremely messy.


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  20. Z71bill

    Z71bill

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    I get a few drips out of my secondary / back up drain line - it ends up in the overflow pan - I think if I install a P trap on my main drain line it will solve this problem.

    Was planning on doing this once it cools off - now I may put a p trap on both lines.
     
    Last edited: Sep 15, 2015