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Confused- Intermittent Water Leak out of A/C Handler

Posted by kes_cor (My Page) on
Thu, Jul 19, 12 at 8:25

Im hoping someone can help with my strange problem..

We had an A.c and air handler (American Standard) installed for the upstairs zone. The unit is upright, meaning the air comes up from the bottom of the unit through the cooling coils into the attic.

In the front, the installers but in solid 3/4" (I think) pipe which runs across the unit, with a trap (bend) and into a condensate pump, which pumps the water off to the basement. I understand this is this way to allow access to change the filter & to prevent an "air lock" which prevents water from draining through the line.

Here is the problem.. Most times this works fine..

Two times in the last month, there is water leaking (a LOT) out of where the pipe connects to the Air Handler.

On about the Second of July-
The first time was when we had a power outage for 36 hours, the house temperature climbed to 90 degrees. when the a/c turned on, it was set to 76. I noticed a strange gurgling noise and saw a little water coming out. I shut down the unit and the water poured out. I turned the a/c back on and the rest of the night no leaks.

Last night 7/19 was the second time.. The house temp was 80ish outside was low 90s, and I set it to 76.. After about an hour, i noticed it was leaking out the front. I shut the unit down, water poured out, and then no problems the rest of the night.

Other relevant information - we have been using the A/c daily between these two times, it has been in the 100's & 90's for a lot of the days in between. THe A/C system was installed 9 years ago and I've never cleaned the drain pipe.

Thanks for your help


Follow-Up Postings:

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RE: Confused- Intermittent Water Leak out of A/C Handler

It sounds like you have a clogged drain trap. The trap can't pass the water fast enough when the AC is running for long periods of time, but can do so when normal use. This is going to get worse over time. The trap should be cleaned once a year.

Does the trap have an opening which would allow you to clean it out?


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RE: Confused- Intermittent Water Leak out of A/C Handler

It is one solid pipe, pvc, which is screwed into the air handler and glued together. I can not unscrew it as it is 2' long or so, and next to a wall. I would need to cut it off and reconnect it. I do have access to the exit point by dropping the condensate pump and maybe suck it out with a shop-vac?


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RE: Confused- Intermittent Water Leak out of A/C Handler

"n the front, the installers but in solid 3/4" (I think) pipe which runs across the unit, with a trap (bend) and into a condensate pump...'

Mike meant the trap. Does it have an opening? Mine does. Came with a cleanout brush.


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RE: Confused- Intermittent Water Leak out of A/C Handler

I pulled out the shop vac and sucked it out, No idea if anything came out of it i guess it is a wait and see from here.

I did want to add that it seems that the pipe cant keep up with the flow, however, for 3 days we were above 100 degrees and the a/c was running full time to maintain a 76 degree, so using that logic, i would have thought it would have leaked. The condensate pumo was running about every 10 mins or so.

Here is a picture of the trap i'm dealing with.


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RE: Confused- Intermittent Water Leak out of A/C Handler

I would make sure that the horizontal pipe has enough downward pitch to assure flow into the pump.

Here is a link that might be useful: mine looks like this


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RE: Confused- Intermittent Water Leak out of A/C Handler

It does appear you do not have enough pitch to ensure drainage. All it takes is a bit of negative pitch in the line to set up what I refer to as a "double trap" This will set up an airblock in the line and prevent drainage. A simple rebuild of that line should correct it. Check out weedmiesters link.


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RE: Confused- Intermittent Water Leak out of A/C Handler

I haven't changed anything in the line since i sucked it out and it hasn't leaked. Since it happens every so often, i decided to add a secondary float shutoff valve in that plastic pot on the bottom right of the picture. I wired it in series with the condensate pump.

When ever it overflows, it fills that bucket well, i wasn't sure about putting it inside to the secondary drain pan and if a problem should arise, i can remove it from the circuit for troublshooting purposes.

I also tested the wiring & switch to ensure it shuts off the a/c.

Thanks for the suggestions.. If the trap becomes problematic again, i'll look to rework the drain line.

Here is a link that might be useful: Float Switch


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