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  1. #1
    Join Date
    Jul 2008
    Posts
    6

    Help Weird Drain Issue

    I just had my entire system replaced, compressor, furnace, coil, etc... I turned it on last Friday and it was running fine all weekend. Last night I got home from work and noticed it was very hot... I went up to the attic and the drainpan was full of water.

    This morning the tech came out and checked the drain lines. There was a cap on top of the main pvc drain line at the furnace. When he unscrews it the water starts draining down the pipe properly. He said it was really weird and that it should work with the cap on.

    When I look at the coil there are two pvc pipes. Both of them have a vent coming up. One of them is the main drain with a p catch that overflows into the drainpan. I am not sure where the other goes but it has a vent as well that the tech said should not have the cap on it.

    The tech left the cap off for now but was at a loss as to why it is doing this. Does anyone have any clues or somewhere I could point them when they come back later in the week? I would tell them to leave it with the cap off but when it is not on and the air is running it feels like I am losing alot of air out of the vent.

    Thanks in advance for any help or pointers.

  2. #2
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,743
    sounds like the main drain may have a second trap in the line.

    could just be a dip in the line but they can cause problems.

  3. #3
    Join Date
    Dec 2005
    Posts
    1,918
    Put the cap back on and drill a small hole on top of it. This will enable the proper drainage and you will loose much less air. Yes, you need to vent this cap.

  4. #4
    Join Date
    Jul 2008
    Posts
    6

    Drilling the hole

    Quote Originally Posted by just_opinion View Post
    Put the cap back on and drill a small hole on top of it. This will enable the proper drainage and you will loose much less air. Yes, you need to vent this cap.
    I was actually just thinking of this right before I read your post... I will give it a try. Better than losing all that air back into the attic if I dont have to.

  5. #5
    Join Date
    Nov 2007
    Location
    panama city beach (aka lower alabama or LA) FL
    Posts
    93
    when the coil is placed on the discharge side of the blower it creates a positive pressure on the drain lines which is why a vent is needed before the trap. soremove the cap the air loss from that small opening is worth the cost of not having to replace your ceiling..............save a ceiling ask your contractor to install an E-Z trap a float switch and a wet switch !!!

  6. #6
    Join Date
    Jul 2008
    Posts
    6
    Quote Originally Posted by dad211 View Post
    when the coil is placed on the discharge side of the blower it creates a positive pressure on the drain lines which is why a vent is needed before the trap. soremove the cap the air loss from that small opening is worth the cost of not having to replace your ceiling..............save a ceiling ask your contractor to install an E-Z trap a float switch and a wet switch !!!
    What is an E-Z Trap? They did install the float and wet switch which is what saved my ceiling yesterday

  7. #7
    Join Date
    Nov 2007
    Location
    panama city beach (aka lower alabama or LA) FL
    Posts
    93
    an e-z trap is a p-trap that has a float switch built in so if you have a clog in the trap or any where in the drain after the trap it will shut down the ac system before it fills the pan put E-Z trap in yoursearch engine and it show you the web site good luck

  8. #8
    Join Date
    Apr 2008
    Location
    Florida
    Posts
    33

    hmm

    have the tech redo your drain line or fix it properly *send someone better
    if he cant at least make a new drain and make it work properly he needs to leave your home immediately

  9. #9
    Join Date
    Jun 2007
    Location
    Atlanta, GA
    Posts
    61
    Quote Originally Posted by dad211 View Post
    when the coil is placed on the discharge side of the blower it creates a positive pressure on the drain lines which is why a vent is needed before the trap. soremove the cap the air loss from that small opening is worth the cost of not having to replace your ceiling..............save a ceiling ask your contractor to install an E-Z trap a float switch and a wet switch !!!
    dad, can you tell me where you can get any information on the drain line needing a cap to relieve pressure? Is it in a manufacturers INO manual or in any HVAC textbook?

  10. #10
    Join Date
    Mar 2005
    Location
    Suppy NC
    Posts
    4,513
    Quote Originally Posted by jb00gz View Post
    have the tech redo your drain line or fix it properly *send someone better
    if he cant at least make a new drain and make it work properly he needs to leave your home immediately

    those are some hard words. The tech was being honest and not acting like a know it all. IMO this makes for a good honest tech. People come here complaining of dishonest techs and finaly one comes along and he is shot in the head

    if the static pressure is high going through the coil and a trap is install on a positive pressure coil the air will or can turbulate in the drain line and hold the water in the tray. His removing the clean out cap relived the static and as the air blows out the hole the water will drop down into the trap

    fix is imo exten the vent so water can not blow out or back up and out

    remove the trap and run the drain straight

    ez trap will also do this if the static is high.

    have been seeing this for years and not all systems will have this problem.

    first time i saw this was with an ez trap and you could see the water do nothing till you poped the cleanout then gush out of the tray put the cap on and the water would stop draining. Strange but does happen

  11. #11
    Join Date
    Dec 2007
    Location
    Afton, VA / Khorat, Thailand
    Posts
    2,469
    Quote Originally Posted by tinknocker service tech View Post
    those are some hard words. The tech was being honest and not acting like a know it all. IMO this makes for a good honest tech. People come here complaining of dishonest techs and finaly one comes along and he is shot in the head

    if the static pressure is high going through the coil and a trap is install on a positive pressure coil the air will or can turbulate in the drain line and hold the water in the tray. His removing the clean out cap relived the static and as the air blows out the hole the water will drop down into the trap

    fix is imo exten the vent so water can not blow out or back up and out

    remove the trap and run the drain straight

    ez trap will also do this if the static is high.

    have been seeing this for years and not all systems will have this problem.

    first time i saw this was with an ez trap and you could see the water do nothing till you poped the cleanout then gush out of the tray put the cap on and the water would stop draining. Strange but does happen
    Yea, sometimes it will just gurgle alot. Needs to be vented .
    Tough times don't last...Tough people do.

    Midnight Sun Astrophotography

  12. #12
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,063
    The vent, is on the wrong side of the trap.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  13. #13
    Join Date
    Mar 2005
    Location
    Suppy NC
    Posts
    4,513
    the true fix is to lower the static pressure, this would in most cases require duct vhanges and so on

    most likely not going to happen so quick fiz is vent or remove the trap

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