I Have two small pipes that come from underneath the house in the back near the Air Conditioning system the drips water occasionally. What are these two small pipes?

I Have two small pipes that come from underneath the house in the back near the Air Conditioning system the drips water ocassionally. What are these two small pipes?

My guess would be that one is a AC condensate drain and the other could be from.
1) The water heater T & P valve **OR**
2) A water heater or a washer overflow pan drain.
If you don't have overflow pans then it's number one. Cheers, Tom

How many AC units do you have in your house? One or two ?

Each coil ( the part of AC located in the attic ) has 2 - 3/4" drains. They drain condensation. One is connected to the coil itself, the other one to the drip pan below it. In my area of operation, these two drains have to be dedicated and cannot be combined into one drain.

The coil drain should be draining into a trapped fixture, like sink. It is connected to the drain under the sink via Branch "T". . It has water in it all the time and drains continuously while AC is ON.

The other pipe ( pan drain ) should go to the outside and terminate above window (... at least in my area ) . That's is so you notice when it drips. If it drips, it tells that there is something wrong with the condenser and water is in the drip-pan. In other words, it is giving you a Warning.

Some AC installers run both pipes to the exterior. It is against the Code in my area but it may be allowed in your area. If that's the case than there is nothing wrong with you AC only problem with installation. If it is the drip pan drain that leaks, than it tells you that your drip pan is full of water just about to overflow onto your ceiling. That would than indicate either clogged drain or excessive condensation from your coil. You hope for clogged drain.

Go to the attic and check you AC unit. If it is full of water than locate the drain inlets , take a coat hanger and unclog them... If problem persists, call AC repairman to take a look at that...

I suggest that you also post this question in AC forum. It is more AC related problem rather than plumbing...

Let us know what you've found out. Good Luck. Milo

Milo, How did this get to be a AC problem?
I suggest that you also post this question in AC forum. It is more AC related problem rather than plumbing... Go to the attic and check you AC unit. Why should he have to go up in the attic if all he was asking was what were the two pipes? Did you not under stand his question? He wasn't complaining about anything, he was asking a question.

Each coil ( the part of AC located in the attic ) has 2 - 3/4" drains. They drain condensation. One is connected to the coil itself, the other one to the drip pan below it. In my area of operation, these two drains have to be dedicated and cannot be combined into one drain. The other pipe ( pan drain ) should go to the outside and terminate above window (... at least in my area )
I guess things have changed a lot since I retired. My-My but they do things a lot different out in UPC land. Just imagine that! Using two drain lines to drain one source, and terminating one of them above a window yet, ( which is against code in my area).
As a plumber I've been called out countless times to clear a AC condensate line bercause the home owner thought he had a plumbing leak. In every one there was just a single pan drain that had built up crud and overflowed the pan.
The coill itself set directly above the pan and dripped into it, as it does on my own unit . To have two condensate drains means that there must be two pans under coils.
Now I'm no AC guy but that doesn't make much sense to me. Sort of like a toilet bowl with two tanks connected, or perhaps two drains in case one clogs up. If you have one pan collecting condensate why install a pan directly under it? In case there's a blockage in pan one? Why stop there? It's possible for pan number two to clog up also. Enter pan number three to set under pan one and two. Does anybody else see how silly this is?
Granted , out in Milos territory they have some mighty strange codes.
But Hey! I'm willing to learn. So if they're making AC's with double condensate pans, clue me in? But please explain why they're needed! Cheers, Tom

Tom, poster says that "... this line ...drips occasionally..." . If it drips, it indicates a problem. That pipe is near his AC. Therefore, I suggested to him to prevent possible overflow of his drip pan onto his ceiling and to go to the attic to check on his coil. I assumed his unit is in the attic, as most of them are. But it can also be an upright unit in a dedicated closet. In this case, he would not go to the attic but this closet. In either case, that pipe should not drip. His primary condensation line is not installed properly or his drip pan is overflowing. No way around it, Tom. I hope now you will understand.

As far as for 2 lines - well that's how it is done and purpose is as I explained in my initial post.

How do they install AC in your area ? Please, do share with us...

Hope you are enjoying your Sunday, Tom ! Milo


Tom, as always, I feel honored to be able to admonish you, the Expert, on the new installation methods that has evolved since you were in the field. I looked up this video clip on the Internet for you to see. Perhaps, this will better explain what I was trying to explain to the poster in my initial post. Enjoy! Milo

How to Stop Air Conditioner Condensation Drip: Home Improvement & Repair on Video | eHow.com (http://www.ehow.com/video_4419035_stop-air-conditioner-condensation-drip.html)

Tom, poster says that "... this line ...drips occasionally..." . If it drips, it indicates a problem.Of course it drips Milo, It's a condensate line ad that's what condensate lines do. They drip when the AC runs. If the line didn't drip while the AC ran I'd certainly think that there was a problem. We just aren't on the same page. You're assuming that he has a newer AC with the double pan and I'm assuming he just has a regular AC with just one pan.
I saw your video, Thanks! As I said I'm always ready to learn. I depend on you younger guys to keep me current on the new stuff.
Is this a standard feature or a add on that the user can order? All the AC units I've ever cleared the drains have been single pan units. But now that you've gone to the trouble of looking up the video I understand a lttle better. I stll think it's a bit of "overkill" but then your code always errs on the side of caution. Is this the way all new AC's come out? Seems to me it would increase the cost of manufacturing and add $ in the form of time and material to the installation. Still think this guy has a problem if the condensate line drips? Thanks again for educating me. Regards, Tom

Yes, I am sure Codes are different in different parts of the country. In my area, primary condensation line has to be drainen into a trapped plumbing fixture. That's the Code. Secondary condensation line is then discharged to the exterior and exits in conspicuous place - like explained in the clip. Secondary line has to have in-line trap and has to have open vent.

It is not an add-on, Tom, it is a standard feature installed with every installation. I do not know if all units come that way - but to tell you truth, I have not seen them installed otherwise. ( except illegal installations, of course ). Maybe AC guys from East Coast could jump in and enlighten us on this issue...

Agree with you, Tom, it may be overkill... but... sorry, I do not make the Rules. I forced to follow them just like everybody else... :D

Have a productive week ! Milo

Let's ask the AC guys Milo. I'll be back with HVAC101s answer. Have a good one.Tom

Most jurisdictions require a secondary drain pan along with a separate drain line going to day light outside for evaporation. Now in this area the main A/C evaporator drain line is not required to be directly connected to the interior plumbing drain system. According to our local plumbing officials they were afraid that under some conditions (the evaporator section being under negative pressure and the drain trap being out of liquid to seal it off like in the winter time when the A/C is not in use) it could cause sewer gas to be sucked into the system. I have to agree with that since I never want to see any part of the HVAC air handling system connected to a sewer drain/vent.

Many of today's modern coils and units have a secondary drain built in. These are only to cover the manufactures A$$ if you know what I mean. These drains will not stop damage from an overflow but are there so the manufacturer is covered. The secondary drain is well worth the effort and cost since they usually extend the entire width and length of the unit so no matter where the water comes from in the unit it will be caught and properly disposed of.

Many areas are now accepting a float switch assembly and if properly located will shut down the outside unit so it will generate no more condensate until the service people arrive and fix the drain problem. While these do work they are not as good as an auxiliary drain pan in my opinion. I will post some pictures for you all on the plumbing link provided.

The Auxiliary Condensate Overflow Safety Switch, is an easy-to-inspect float switch that is installed in the drain line to detect upstream clogs and interrupt the thermostat circuit to shut off the unit before flooding occurs. The switch can also be installed to activate audible and/or visual alarm circuitry.

The switch/holder assembly is easily removed to enable cleaning of any clog in the line.



Fluid Systems Design Parameters
Easy to inspect and maintain
Compact design for vertical or horizontal installations, inline or plugged
Detects clogged A/C condensate drains and shuts off the system
Can be installed to activate audible and/or visual alarm circuitry
UL listed, complies with applicable building codes

Someone's idea of a good time. LOL Drains going no where lol.

Check out this link for some other styles of drain traps with cutoffs.


http://images.google.com/imgres?imgurl=http://www.hvacsolutionsdirect.com/image.php%3Ftype%3DT%26id%3D118&imgrefurl=http://www.hvacsolutionsdirect.com/home.php%3Fcat%3D286&usg=___p9NvQiRFUNeDSzWQagPv1Ty42o=&h=698&w=579&sz=37&hl=en&start=42&um=1&tbnid=ZfdFWLgiwphbFM:&tbnh=139&tbnw=115&prev=/images%3Fq%3DAc%2Bdrain%2Bline%2Bfloat%26ndsp%3D18 %26hl%3Den%26sa%3DN%26start%3D36%26um%3D1 (http://images.google.com/imgres?imgurl=http://www.hvacsolutionsdirect.com/image.php%3Ftype%3DT%26id%3D118&imgrefurl=http://www.hvacsolutionsdirect.com/home.php%3Fcat%3D286&usg=___p9NvQiRFUNeDSzWQagPv1Ty42o=&h=698&w=579&sz=37&hl=en&start=42&um=1&tbnid=ZfdFWLgiwphbFM:&tbnh=139&tbnw=115&prev=/images%3Fq%3DAc%2Bdrain%2Bline%2Bfloat%26ndsp%3D18 %26hl%3Den%26sa%3DN%26start%3D36%26um%3D1)

HVAC101,
Thank you for clearing that up. Is that picture what a double pan drain set up will look like? Seems to me if you tied those pipes to a barrel of mash and lit a fire under it you could produce some mighty fine white whisky. ^Thanks again for popping in. Tom

Is that picture what a double pan drain set up will look like

In a perfect attic install the pan will look something like in the picture. Now we all know most of those type of jobs are never perfect. LOL