Clearing A/C Condensate Drain Line

[Major Ramifications]

The central A/C system on our house has a 1/2" PVC drain line to remove the water that condenses on the evaporator coils. The line is clogged and I'm having trouble clearing it.
I've tried compressed air, bleach, and now I'm looking for something I can snake it out with. I tried some solid aluminum vinyl coated wire, but I couldn't get it past the first elbow. I put a small loop in the end to help it round corners, but it didn't work.

How can I unclog it and what can I do to prevent this in the future? I think there are some pellets that I can drop in there occasionally.

Also, there is a PVC "T" coming off the evaporator assembly with the short part facing up, open to the atmosphere. Some cool air blows out of this and is wasted in the attic. If I plug it, will the line still drain OK?

 

[CNGsaves]

If you've put that much effort in clearing line and still clogged, I'd just cut it all off and put in larger PVC line like 3/4" or even 1".

PVC is cheap and easy to work with . . . hacksaw is all you'll need.

 

[EOC_Jason]

If compressed air didn't unclog it, it's got to be pretty bad. I don't know what would be stiff enough to unclog it but flexible enough to make it around 90 degree bends... Maybe trace it to the other end and try from there?

The "T" is there so you can occasionally pour some diluted bleach in with a funnel to keep the line clear. Yes, it's okay to put a cap on there, just barely stick it on so you can pull it off later.

Pan tabs are also okay if you can open up the side panel to put them in the drain pan. You can usually pick them up at A/C supply stores, maybe Grainger?

 

[JCoggin]

Be careful using bleach. If you have a metal drip pan and it gets in there you cannot stop the rust that will follow. Trust me on this one. That "T" not being capped off can also cause you some drainage issues. The positive pressure on the drain line keeps things flowing. Seems like my drains are 3/4".....

JC

 

[EOC_Jason]

Forgot to mention, you can also use Simple Green... It probably is safer for metal drip pans...

 

[Major Ramifications]

So the tablets are not chlorine based? I know bleach rusts steel badly, but I figured that the tablets were probably chlorine also.
Simple Green? I wouldn't have thought of that.

I should have mentioned that the other end goes down below the decking in the attic and then into a wall, so without cutting out sheetrock, I have no access to the other end. And I can only guess where it ties into the drain line.

I'll take another shot at it tonight, after the sun goes down. After I get the thing cleared, I'll put a loose ****** and cap into that tee.

And maybe it is 3/4" and not 1/2". I haven't fooled with pipe in a long time, so I may be wrong.

 

[EOC_Jason]

I just looked at a bottle of pan tablets we have and it doesn't say what they are made from. It just says stuff like biodegradable, non-corrosive, water soluble (I would hope so!), etc, etc... Doesn't mention anything about metal pans or whatnot.

Also worth mentioning is if you use pan tabs is to make sure you don't get them near the drain line, if one floats in it can clog your line up real quick.

Stick to just pouring a liquid down the line a couple times a year, you'll be okay.

 

[rockchucker]

How much PSI did you get in there with air? If you have over 100 PSI sealed up and it is still not blowing through then that is a HUGE clog. You may try taping the **** out of the nozzle into the Pipe to get a good seal and try the air again.

Another thing I have used in the past to clear drains is this...

http://www.sears.com/shc/s/p_10153_...i_sku=SPM7414506711&sid=IDx20130125xMPTLSx025

They work great. If it fits in the Pipe. You just hook up the Hose, turn on the water, the Bladder expands and makes a solid seal. It will build up to the pressure in your Supply System so be careful. You are guaranteed to find any weak link in the Drain System and blowing apart at ~50+ PSI full of water sure can make a real mess. =)

 

[BillK]

mj,
I have never had an issue with the one at home, but the one at the shop is always getting clogged up. 175 PSI of shop air always manages to get it clean

 

[Highbeam]

If the bends are not 90 degree bends, an electrician's fish tape might make the corner and give you more physical hitting force.

 

[Major Ramifications]

I did have trouble making a seal with my hand attempting to bridge the gap between the blow gun and the pipe. I was afraid of blowing something apart inside the wall.

 

[PT Doc]

Cut near the point where you can't get past and install a tee with a cap and then you'll have a way to unclog it again. I don't know type of PVC you have but 175 psi could end up being ugly. PVC ic cheap. Might just be easier to rep limb with larger diameter. New code might require a p trap off the coil.

 

[EOC_Jason]

I did have trouble making a seal with my hand attempting to bridge the gap between the blow gun and the pipe. I was afraid of blowing something apart inside the wall.

Use a wet rag to make a seal...

 

[Scott r c]

If compressed air didn't unclog it, it's got to be pretty bad. I don't know what would be stiff enough to unclog it but flexible enough to make it around 90 degree bends... Maybe trace it to the other end and try from there?

The "T" is there so you can occasionally pour some diluted bleach in with a funnel to keep the line clear. Yes, it's okay to put a cap on there, just barely stick it on so you can pull it off later.

Pan tabs are also okay if you can open up the side panel to put them in the drain pan. You can usually pick them up at A/C supply stores, maybe Grainger?

Actually the "tee" is there to allow air to vent the drain line. If you have a high efficient system it will not drain with out the tee open. I would not plug it off. Also I would cut it out and replace it with 3/4" anyways as 1/2" is generally not used.

 

[rlitman]

Is this white or grey PVC? The white PVC when exposed to sunlight can let light into the center, which can breed algae which can clog the pipe (clear tubing also has this issue).

 

[ishiboo]

Actually the "tee" is there to allow air to vent the drain line. If you have a high efficient system it will not drain with out the tee open. I would not plug it off. Also I would cut it out and replace it with 3/4" anyways as 1/2" is generally not used.

+1. Just like a plumbing vent stack... that open-air tee greatly increases drainage velocity/etc.

 

[Randy in Maine]

Can you get a stiff weedwacker line to go in there?

 

[Boyd]

Cut near the point where you can't get past and install a tee with a cap and then you'll have a way to unclog it again. I don't know type of PVC you have but 175 psi could end up being ugly. PVC ic cheap. Might just be easier to rep limb with larger diameter. New code might require a p trap off the coil.

Yep.

 

[welder4956]

Why not cut the PVC and insert a valve to isolate it from the AC coil pan and a tee downstream of the valve with a hose connection? Then run a hose up there and flush it out with water. Also, no need to leave the tee open as a "vent". It will get plenty of air for drainage through the opening in the drain pan. I have an upstairs and downstairs unit and both do not have "vents" and drain just fine. If you really feel like you need a vent, you can use an elbow to turn the hose connection up and leave it open.

 

[Major Ramifications]

Success!
The compressed air finally got it taken care of, thanks to the wet rag.

I was wrong, it is 3/4" PVC and not 1/2" like I had previously stated.

Just to clarify, this is the main drain line, not the secondary line from the sheet metal drain pan below the unit that acts as a backup drain in case the main clogs.


One more question:
Couldn't I put one of those "bent" PVC traps between the evap unit and drain tee to keep the cold air from being wasted out of the tee and still allow the line to drain well?
It seems to me that there should be plenty of air from the air handler to help it drain, but I'm no expert.

 

[larry_g]

Didn't read this soon enough to help, but I have used speedometer cable to snake out small diameter pipes. You can attach it to your drill motor to get some auger action.

lg
no neat sig line

 

[RECox286]

The joys of today's technology...

Uncle Bob

 

[EOC_Jason]

FYI, while you were up there, you *did* check your secondary line and blow it out just to make sure no critters made a nest in the pipe, didn't you???

You mean a P-Trap? Yes, you can put one in there. I've seen units with and units without. It kind of depends on how the drain line is piped, because you obviously wouldn't want sewer gas to get sucked in...

One more question:
Couldn't I put one of those "bent" PVC traps between the evap unit and drain tee to keep the cold air from being wasted out of the tee and still allow the line to drain well?
It seems to me that there should be plenty of air from the air handler to help it drain, but I'm no expert.