# My AC Unit drains into my bathroom sink - Drainage Problems



## joecaption (Nov 30, 2011)

Not sure what would make you think that was a good idea.
It should be ran outside.

Are you on town sewer or a septic?


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## DavidATX (Jul 16, 2012)

*Well...*

Well you see I didn't do the plumbing myself. This is something existing that has been in place since the 80's. From what I understand it's not really done this way anymore because of the problem I'm describing. Just wondering if anyone knows what to do here.


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## biggles (Jan 1, 2008)

the trap on a ac unit anysize even rooftops is to liquid seal the trap line opening into the pan so your not suck/blowing air out thru it.HD/LOWES sells traps for units and it need to be as close as possible to the condensate pan connection to trap asap the air with the water.that sink connect is a trap but the sink drain is compromising the trap idea..TEST:wink:if you put a wet paper towel over the sink opening the unit will trap out the condensate water from the pan using that sink trap...only time the condensate will drain the other way is when the fan is off.forget the pitch don't need one if it is trapped just level into a T


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## DavidATX (Jul 16, 2012)

*Oh duh!*

So you think something like this would work to solve my problem?


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## biggles (Jan 1, 2008)

thats a start but you still need the trap near the unit..with that idea sure the unit is using the sink trap but if the unit is negative sucking air thru the unit condensate line you will get the sewer smell thru the unit....just do a trap off the unit condensate and get off the sink trap idea.the main reason for a trap is sewer smells but with AC it is the sealing of the water draining out not being effected by air either way


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## NitrNate (May 27, 2010)

so what exactly is the problem causing the line to back up? are you sure the line isn't clogged at some point before it connects to your sink drain? my condensate line is plumbed that way and it is before the sink trap on purpose to keep sewer gases out of the air handler. all the houses in this area have condensate lines plumbed that way. it all depends on the code in your area.


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## DavidATX (Jul 16, 2012)

*Well...*

For the most part it is clear but recently I got my AC recharged and it's putting out a lot more condensation ... the water from the line doesn't make it through my "trap" so it winds up spilling over ...


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## NitrNate (May 27, 2010)

first thing i would do is let the condensate line free flow into a bucket under the sink and see if any back-up occurs before assuming it has anything to do with the under sink connection. clean out the p trap and clean out the under sink T while you are at it making sure all piping prior to the main drain are free and clear. you could have a partial clog in the condensate line that has just been worsened by the greater flow.


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## TheEplumber (Jul 20, 2010)

What am I not seeing here? I plumb condensates to floor drains, hub drains, tub wastes, sink tailpieces, auto wash boxes, etc. all the time.
Is your unit higher then the sink? If its a plumbing trap issue why isn't the sink overflowing instead of the pan?


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## Kirsten83 (Nov 11, 2015)

What was the outcome of this? I'm having this problem now


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## Kirsten83 (Nov 11, 2015)

TheEplumber said:


> What am I not seeing here? I plumb condensates to floor drains, hub drains, tub wastes, sink tailpieces, auto wash boxes, etc. all the time.
> Is your unit higher then the sink? If its a plumbing trap issue why isn't the sink overflowing instead of the pan?


We are having this issue now: what was the fix in this situation?


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## Ghostmaker (Mar 2, 2013)

MY guess is you need to blow compressed air down your air conditioning drain. Probably clogged with algae.


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## REXTER (Oct 26, 2016)

For those who were looking for the same answer but could't find one here that fits the bill, here's my solution:

I live in an apartment complex built back in the 1980s with the same sort of setup in the bathroom. Been here for going on seven years, and every year, without fail, at the beginning or end of or both of the hot season in SoCal, the maintenance crew is called to clear out the drain line with a vacuum cleaner. A new guy came by who had some experience with the same problems in other properties told me that he'd replaced the bathroom drain fitting with a three-quarter inch wye instead of the half inch available in most dishwasher drain fittings. 

He said that hair, grease and other gunk blocks the wye as it enters the main line at the diverter, whether the AC is used or not. Said he couldn't find any of the three-quarter inch fittings at Home Depot, so I went to Lowes where I found such an animal after some searching. I had to use the same upper washer asa the smaller fitting instead of the one that came with it, but it works great, according to the maintenance guy. 

I decided to go ahead and do it myself as the parts were less than $8 and change.

You'll probably need to buy a 3/4 to 1/2 inch REDUCER and a cheap hose coupler for under a dollar as opposed to the nylon ones that are more expensive.

Cut the new fitting, making certain you'll have enough room for the lower section to bottom out in the trap and still be able to connect it to the existing line. Hope this helps someone out there! :glasses:


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## jrepp44 (Jan 6, 2010)

Do you live in a hot/humid climate? If so, make a cup of strong bleach solution using very hot water and pour it down your A/C drain about one a month in the summer, you may have a buildup of algae, mold or mildew. If the condensation line is completely clogged, you will need to use a shop vac or special pump to remove the clog from the line.


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