Central A/C issues

[Phoenix86]

I'm an idiot when it comes to A/C, but not completely incompetent so bear with me...

Central A/C unit in the attic is draining water into the overflow pan, it's starting to fill and getting drained to the outside pipe. There is water pocketing in the insulation wrapped around the unit in the attic and it's dripping down into the ceiling near a vent. The main drain is connected to what I assume is the drain for the washer as it runs to that part of the house. There is an opening at the top of this pipe, I assume so you can see if it's full with water, it is.

A few weeks ago we ran a coat hanger down the main drain pipe, the water emptied and we cleared the overflow pan. The water dripping into the ceiling stopped and no more water was running into the overflow pan. Awesome. Fast forward to yesterday and the problem repeated itself. I cleared the main drain again, however this time the problem repeated itself within 24 hours. I cleared the main drain again with the hangar, the backed up water again drained but obviously this is going to happen again.

This time I got to it before the condensation built up inside the insulation around the unit so no water was dripping into the ceiling. I assume that part is a symptom of the problem, since it seems to go: main drain backs up->overflow pan fills->overflow drains->water drips from the unit into the insulation->water drips down to the ceiling.

This is my sister's house, so I don't have much backround on it and she's pretty ignorant, it's about 5 years old.

Is this something I can troubleshoot/fix easily or am I looking at calling someone out?

Thanks in advance.

 

[jagec]

Well, you need to do a proper unclogging of the drain, the hanger is just a temporary fix. Snake it and report back.

 

[MrPickins]

Well, you need to do a proper unclogging of the drain, the hanger is just a temporary fix. Snake it and report back.

This.

Mine does the same thing and I have to snake it from both sides at least once a year to avoid leaks.

 

[KK]

did someone say you gotta clean your pipe? It'd put you at ease.

 

[Phoenix86]

I just want to make sure the main drain is the problem, I assume it is but assuming something when I know as little as I do can be dangerous.

Snaking it might be a pain, it's a small pvc pipe about 1/2" and runs about 30' with a 90 degree bend about 4' away from the A/C unit. I read elsewhere hooking up a shop vac to the outside end of the pipe might clear it, gonna try that next.

 

[olds]

If you use a shop vac, be sure it doesn't suck air in around the hose where you hook it up to the pipe.
I'd be tempted to drag a hose up there and force some water through it. But with my luck, the pipe wouldn't be glued together and I'd blow it apart.

 

[Phoenix86]

Shop vac is a no-go, got it 99% sealed and nothing came out. It's a 5HP/6gal model so it has some power. I think Jagec is right, gonna have to snake it but I don't have a snake available. I assume I can rent one but I'll have to find one small enough for the pipe, a typical plumbers snake head will be way too large.

 

[quackagator]

You could blow it out with a compressor.

 

[Phoenix86]

Compressor wouldn't be so easy, I'd have to disconnect and seal one end of the pipe. Gonna pick up a hand snake that looks small enough to fit the pipe, something like this:

http://www.homedepot.com/p/RIDGID-Kwik-Spin-41348/203203829#.UbEfy5xDL6w

 

[PottedMeat]

had something similar happen to my parents AC. the condensate trap led to the primary drain ( went to one of the bathrooms ) and a secondary exit near the roof. the trap kept getting clogged and so did the primary drain. i ended up sawing off the bent pvc trap and making my own out of elbows and attaching it to the secondary drain. haven't had any problems since.

 

[MrPickins]

Get something like this:

http://www.amazon.com/General-Cleane...ds=drain+snake

 

[Greenman]

Use the vacuum again, but this time drop in a chunk of sponge with a string tied to it at the top. If it gets stuck, you'll be able to pull it back out, if it goes all the way through, you'll be able to pull it back through to get the crap it missed on the first pass.

Side note: From your description, it sounds like the AC condensate is draining into the sanitary sewer, that shouldn't happen. It should simply dump on the ground.

 

[TastesLikeChicken]

I use a water hose with a spray nozzle based on a tip I got from an AC guy. Once the water pressure from the hose has cleared the main blockage pour in some bleach to kill the algae/bacteria buildup. The bleach treatment should be repeated yearly as a preventative measure.

 

[Red Squirrel]

I don't get why some house builders put the hvac in the attic. What a pain in the ass it must be to work on it.

What's the weather like there, could the water be freezing in the P trap overnight?

 

[stormkroe]

you could also replace the 1/2" with 3/4" and whatever is clogging it may never be able to bridge or get a 'foot hold' again. warning, it could cost as much as $9.

 

[Phoenix86]

Here's a pic of the setup, top pipe is the main drain, bottom one is the emergency drain into the pan. As you can see it's already starting to rust (may have had some prior to this, not sure).

I think the clog is at or just after the the 90 degree bend in the pipe at the bottom of the image. The open end just past the p trap is where I see water in the pipe, it's filled just past the p trap.

I can't run forced air/water down the open end or it'll just blow back into the A/C, if I cover the open end with my finger and blow into slightly I can hear it going that direction. Only way to do that would be to disconnect it from the A/C unit and seal that end off while I run compressed air/water through the rest of the pipe.

The other end of the pipe runs to the exterior wall outside the house, near where the washer/dryer is. I'm not sure if that pipe connects to the drain for the washer so that end might be open too with another T connection to the washer. I'll have to do some more digging around to see if that's the case tomorrow.

Easiest solution is to just snake the pipe, I found someone who will loan me a 1/4" snake so I'll try that tomorrow but I'm still concerned about that sharp angle.

 

[Phoenix86]

Use the vacuum again, but this time drop in a chunk of sponge with a string tied to it at the top. If it gets stuck, you'll be able to pull it back out, if it goes all the way through, you'll be able to pull it back through to get the crap it missed on the first pass.

If the suction isn't getting to where the water is filling the pipe at the top it wouldn't get to the string/sponge. It's possible there is another opening in the pipe where the washer hooks up so I may have just been sucking air from there, will have to check tomorrow when I have a bit more time. If snaking the pipe isn't successful I'll try this while capping off the laundry room opening. Thanks.

 

[Phoenix86]

I don't get why some house builders put the hvac in the attic. What a pain in the ass it must be to work on it.

What's the weather like there, could the water be freezing in the P trap overnight?

I'm in Texas, it was 95 degrees on Wednesday, doubt this is the issue.

 

[Phoenix86]

you could also replace the 1/2" with 3/4" and whatever is clogging it may never be able to bridge or get a 'foot hold' again. warning, it could cost as much as $9.

I honestly think it's debris from the attic, dust/insulation not algae. Replacing the pipe is something I'd consider if it was my house or of she intended on staying a while but she is likely to sell within a year.

 

[Red Squirrel]

I'm in Texas, it was 95 degrees on Wednesday, doubt this is the issue.

Yikes, that's hot. Yeah not that then. Changing the pipe to a 3/4 is a pretty easy job though, so if you think that could fix it, I'd try that.

 

[squirrel dog]

get a pitcher , fill half n half with bleach and water . Pour into pipe that is open and sticking up . Repeat. Do every year before the heat , and stay strong my neighbor.

 

[PottedMeat]

since you're not going to remove the screw on drain connectors make sure you remove/open the air filter and reach your hand in to the drain tray and check for muck.

 

[jaedaliu]

Just so you know, the vertical part is a vent. Without that vent, water can't drain out at any sort of speed.

Looks like your PVC is cemented very well (based on purple drips) If the coat hanger works, the snake should work better. I hope it's long enough.

 

[Micrornd]

The pipe that is emptying in to the overflow catch pan is the overflow drain line.
It's job is to act as a secondary drain for condensate if the primary drain becomes plugged.
That is why it exits the unit slightly higher than the primary condensate drain.

The pipe that is clogging is the primary condensate drain pipe.
This line should be the same size (or larger than) where it leaves the A/C unit for its entire length.
This is for both mechanical strength and to prevent clogging.
It should empty onto the ground (or into a dry well, NEVER into a sanitary or sewer line) and always with an air gap between it an where it is dumping.

Someone (probably new in the business) took a shortcut and reduced the size of the line leaving the unit.
Remove the reducing 90, and run a new section of PVC the same size all the way to the dump point (priming and gluing all joints).
Leave the rest of the existing pipe as is.

You should also put a piece of 3/8" galvanized hardware cloth (oversized screen) over the end of the drain line to prevent small frogs crawling up in it.
They like the moisture and can "plug" the line.
Do not use window screen, as the openings are too small and algae will grow on it and can completely cover it, plugging the line.
Clean this screen every time the yard is mowed.

If you want to make it possible to flush or blow out the line you will need to put a valve (cheap PVC ball valve) between the trap (U shaped pipe in the photo) and the A/C unit.
Closing the valve will then allow you to use air or water applied to the vent (open pipe in the photo) and blow out the drain line, just don't forget to open the valve when done or you'll be right back where you started.
A little bleach solution twice yearly will keep down the algae growth.

 

[olds]

The above is very good.

I'd guess it's clogged at one or both of the red circles. Probably at the one closest to the unit. I am not sure how the line is attached to the unit but it looks like it needs to come off to clean the section up to the vent/drain line. I wouldn't blow debris back through the line into the unit.

As far as blowing out the line, you could cut at the green line, blow it out then put in a coupler.