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Leaking AC Drip Pan

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  • Leaking AC Drip Pan

    The AC air handler in my attic has two PVC outlets for condensation, one from the air handler itself and the other from the drip pan below. Both feed into the same a regular drain line. The connection between the drip pan and the PVC pipe is leaking. The float switch doesn't trip, because it is above the bottom of the outlet, so it has been leaking into the attic, down through a wall, and then into my garage ceiling.

    My questions are:
    (1) If there is water in the drip pan does that mean the AC unit itself has something wrong with it.
    (2) If it is normal for water to be in the drip pan, can i just caulk around the outlet, and maybe have some kind of backup like a pie pan with a water sensor in it?

    Thanks,
    Charles

  • #2
    Re: Leaking AC Drip Pan

    Let me just add that after cogitating for a few minutes, doing #2 with caulk seems like a dumb idea. Cutting out a section of the PVC and replacing it with something new (and using pipe dope on the connection) seems like a better one. Whether or not the dripping AC unit is normal behavior, the drip pan somehow needs to be fixed. I just really wouldn't want to have to replace it, because the AC unit is permanently fixed on top of it.

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    • #3
      Re: Leaking AC Drip Pan

      If you can, please try to post a few good pictures of just what is leaking. Can you make up a sleeve out of clear PVC tubing and use hose clamps to repair the problem? In any case keep a wet/dry vac handy and try to clean up any messes. Depending on exactly what is leaking this may be an easy thing to solve or it may require parts replacement by a good HVAC tech.

      Pictures please
      Last edited by Woussko; 06-30-2008, 09:17 PM.

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      • #4
        Re: Leaking AC Drip Pan

        I've attached a picture of the PVC connection to the drip pan that is leaking. There is a drip at the very bottom of that connection, making both the drain and the float switch useless. It obviously needs to be fixed one way or another, but I also would like to know if it is ever meant to be used, or if it is solely for safety if the unit is malfunctioning.
        Attached Files

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        • #5
          Re: Leaking AC Drip Pan

          Originally posted by cpw View Post
          (1) If there is water in the drip pan does that mean the AC unit itself has something wrong with it.
          (2) If it is normal for water to be in the drip pan
          CPW, I'm not HVAC but it sounds like your AC is working okay. When the outside air is hot and humid, the cooling coils become covered with water droplets and the condensate should drip out of those pipes into the drip pan. My AC is in the basement and it drips into the sump pit. There must be some pump involved to drain the drip pan. A PVC coupler or new connection to the drip pan. Hope this helps
          Last edited by reConx; 06-30-2008, 10:15 PM.

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          • #6
            Re: Leaking AC Drip Pan

            Originally posted by reConx View Post
            CPW, I'm not HVAC but it sounds like your AC is working okay. When the outside air is hot and humid, the cooling coils become covered with water droplets and the condensate should drip out of those pipes into the drip pan. My AC is in the basement and it drips into the sump pit. There must be some pump involved to drain the drip pan. A PVC coupler + some pipe should be ez to replace if you got space. Hope this helps
            There isn't much space, but it should be doable to replace it by just cutting the pipe farther back.

            I know that some water should come out of the system, but I'm not sure that it should arrive in the drip pan, because it would seem that it should come out of the unit itself into that top pipe.

            Comment


            • #7
              Re: Leaking AC Drip Pan

              Originally posted by cpw View Post
              There isn't much space, but it should be doable to replace it by just cutting the pipe farther back.

              I know that some water should come out of the system, but I'm not sure that it should arrive in the drip pan, because it would seem that it should come out of the unit itself into that top pipe.
              One other thought while your into those PVC pipes: Make sure those pipes are not clogged or flow rate diminished by mold build up. I have clear pipe on a curved section in order to see build up or mold. HVAC tech also recommended to pour a little bleach in there seasonally to kill the mold. (be sure there is a way for the pan to drain)

              Comment


              • #8
                Re: Leaking AC Drip Pan

                You have an internal drip pan inside the unit(evaporator) and one underneath(auxilary). They are plumbed seperately so you have 2 lines exiting the evaporator location. The auxilary drip pan should not have water in it. The drain for the auxilary drain pan should be plumbed to a visible location to alert the homeowner of the problem. This means the evaporator condensate drain is plugged up. I've had good luck unplugging it with a shop vac from the exit or you can take the panel off and blow a little compressed air in there(make sure the unit is turned off before you do this).

                They make rubber gaskets to attach the pvc pipe to the drip pan. It goes between the drip pan wall and the retaining nut.
                Last edited by gear junkie; 06-30-2008, 10:36 PM. Reason: to confuse you
                Buy cheap, buy twice.

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                • #9
                  Re: Leaking AC Drip Pan

                  Originally posted by gear junkie View Post
                  You have an internal drip pan inside the unit(evaporator) and one underneath(auxilary). They are plumbed seperately so you have 2 lines exiting the evaporator location. The auxilary drip pan should not have water in it. This means the evaporator condensate drian is plugged up. I've had good luck unplugging it with a shop vac from the exit or you can take the panel off and blow a little compressed air in there(make sure the unit is turned off before you do this).
                  Thanks. I'll pop out the primary line's cleanout and check that tomorrow. I'll also turn off and open up the unit tomorrow morning to see what I can see. If there is nothing obviously wrong I'll call in an HVAC tech. I can also pick his brain about how to fix the PVC to auxiliary pan connection.

                  Comment


                  • #10
                    Re: Leaking AC Drip Pan

                    All you'll see is some green slime. Most of the time the 2 lines are run parallel with each other. Most make sure the auxilary drain gets plumbed to a visible location. You should also have a ptrap on the evaporator condensate drain.
                    Buy cheap, buy twice.

                    Comment


                    • #11
                      Re: Leaking AC Drip Pan

                      Originally posted by gear junkie View Post
                      All you'll see is some green slime. Most of the time the 2 lines are run parallel with each other. Most make sure the auxilary drain gets plumbed to a visible location. You should also have a ptrap on the evaporator condensate drain.
                      They are run parallel for about 5 feet and then combine into one. There is a trap on the primary, but the aux has no trap. Is that right?

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                      • #12
                        Re: Leaking AC Drip Pan

                        Originally posted by cpw View Post
                        They are run parallel for about 5 feet and then combine into one. There is a trap on the primary, but the aux has no trap. Is that right?Yes
                        If possible have 2 seperate drain lines.
                        Buy cheap, buy twice.

                        Comment


                        • #13
                          Re: Leaking AC Drip Pan

                          Originally posted by gear junkie View Post
                          If possible have 2 seperate drain lines.
                          Ben,

                          Thanks for all your advice. You called it exactly, except my slime was brown instead of green.

                          The primary line was clogged, I ran a snake down it and it started draining. For good measure i put about 10 gallons of hot water down it to flush out some of the crud. My next step is to get a water alarm like for a water heater pan, and then to see about fixing the aux line.

                          Answers beget more questions.

                          For connecting a new threaded PVC adapter to the drip pan, should I do anything special aside from adding some thread sealant and screwing it in? - Nevermind I saw your note about the rubber gasket after re-reading your first post.

                          For connecting a new threaded PVC adapter to the drip pan, should I do anything special aside from adding some thread sealant and screwing it in?

                          I'm not sure that I'll do two completely separate lines

                          If I do two completely separate lines, do I just drill a hole in the side of the attic and dump it outside? There is only one vent stack to tie into; and tying into a vent stack is something that would require a permit.

                          Is there a good way to clean these low-flow lines so they don't have flow restriction because of built up crud. My little snake certainly didn't get the inside of the pipe very clean, and it is hard to imagine that any snake would without some flow to help it along. Is it a good idea to put some Glug or Thrift down the condensate line (flushing it with hot water afterwards) to help clean off some of the slime?

                          I understand that the primary is trapped to prevent the gases from the vent stack entering the air handler and thus the rest of the house. Why isn't the aux trapped to prevent the gases from entering the attic? Is it just that the attic isn't living space or is there something I am missing?

                          The primary line doesn't have a real trap. It looks like they just heated a pipe and bent it into a U shape. Is this worth replacing?
                          Last edited by cpw; 07-01-2008, 09:19 AM. Reason: Realized Ben already answered one of my questions.

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                          • #14
                            Re: Leaking AC Drip Pan

                            Originally posted by gear junkie View Post
                            All you'll see is some green slime. Most of the time the 2 lines are run parallel with each other. Most make sure the auxilary drain gets plumbed to a visible location. You should also have a ptrap on the evaporator condensate drain.
                            I see them all the time here, but what is the purpose of the p trap if you can not tie it into a waste line?

                            Comment


                            • #15
                              Re: Leaking AC Drip Pan

                              Ben nailed it. The 2 lines should not tie together. The secondary drain pan line should terminate where its easy to see. If theres water coming out of it that lets the person know theres a problem with the main drain line.

                              The P-trap issue is something different. If the coil is in the return-air stream then the drain line has to be trapped in order to drain properly. If the coil is in the supply-air stream it does not need to be trapped unless it is tied directly into a sanitary waste line. If it just drains outside or goes to a floor drain, then theres no need for it to be trapped.

                              Andy

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