A/C condensate drain de-clog & cleanout: this how-to article explains procedures for cleaning or de-clogging a sluggish, blocked, or leaky air conditioning or heat pump condensate drain.
Condensate drain cleaning and unclogging tools and methods are reviewed, including simple steps that a homeowner can take to clear a blocked condensate drain at little or no cost.
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Clogged air conditioner condensate drain lines can form another source of air conditioner or heat pump condensate leakage that can in turn lead to hidden water damage or in some locations an indoor mold problem or bacterial contamination.
Our photograph of a nearly full A/C condensate overflow pan (at left) shows what can happen if the primary condensate air conditioner condensate drain line is clogged and worse, the condensate drain overflow pan is also itself clogged and not draining properly. Luckily we caught this attic mold and bacterial pond before it had soaked the ceilings below.
We see air conditioner or heat pump condensate drain lines clogging for several reasons:
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We like the clogged condensate drain vacuum cleaning approach better than the blow-out approach if we can get this method to work because it is more gentle, reducing the risk of damaged piping, and because we minimize the risk of blowing a plug of crud downstream to a more distant location where it can form a new clog or plug in a long condensate piping run.
[Click to enlarge any image]
Several air conditioning and plumbing suppliers provide easy-to-clean air conditioning condensate cleanout ports such as the one shown above, including the Easy Klear condensate line cleanout (photo at left) that is particularly useful if your condensate drain line has a long run with a slope of less than 1/8" per foot.
This A/C or heat pump condensate drain line cleanout is intended to be vacuumed using a connection to a shop vac.
Sources for A/C or heat pump condensate drain blow-out valves (remember our warning above?)
Watch out: Cleaning out partly-blocked, sluggish A/C or heat pump condensate lines: neither the vacuum method nor the blow-out method will work very well for cleaning a sluggish condensate line that is not totally blocked, since you may simply move air past the blockage rather than removing it.
If you encounter this problem, try hooking up your pump in the "blow-out" configuration, then try filling the condensate line with tap water so that the pump pressure can act mechanically on the clog.
Watch out: connecting a blow-out device or a vacuum device to a condensate drain that is connected to building plumbing drain waste or vent piping may cause some trouble.
These devices should work well for condensate drains directed to the building exterior but depending on piping arrangement (and eschewing for a moment the fact that DWV connections of condensate drains are not recommended without an air gap) using a shop vac you may pull wastewater or even sewage back into the condensate drain.
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(May 13, 2011) Chris Nallie-Courtney said: Thank you! This was very helpful. I was able to clean out my drain line myself.
(June 22, 2011) w.m.cutler said: very educational,did all the work myself,replaced trap and cleanout 3/4 pvc,used air and shop vac. system fine now.
(Sept 25, 2011) Rana said:
Thanks so much! I was able to clean out the drain myself rather than take off work to wait for the A/C tech to come out. And I'm happy to know more about the upkeep of my own home.
(June 20, 2014) Linda Vereen said: Learned so much from your site. What a great service you provide.
Love that you post pictures and details, it makes it easy to understand.
(July 4, 2014) Rance said: Thank you so much for posting the info, etc. on ac condinsate line cleaning and the "proven" options... Tools that you have tried and recommend. Happy and safe 4th of July to you and yours.
(May 1, 2014) Tom Kolter said:
You should check out the Jones Valve, too, available at Supco and Watso, United Refrigeration and Johnstone, the latter two as "Line Drive".
(June 23, 2011) Ma Neumann said:
A neighbor in my condo tells me that our #1 problem with the AC is water clogs--when the condensate drain's slope is too great, he says, the water rushes down the pipe and clogs up all by itself, sort of like a vacuum. I can't find any references to water clogs on the Internet. Everything I see about clogs uses terms like sludge, dirt, debris--solid material, not vacuums. Please educate me.
Your neighbor's explanation makes no sense to me at all. What clogs A/C condensate lines is typically crud (dust, debris, rust flakes from inside the air handler) that collect in the condensate line trap, or at the condensate drip pan opening that feeds into the condensate line.
Excessive slope is a problem on drain lines on SEWER piping (black water, toilet waste) because if the slope is excessive the water can rush down the drain line leaving solids behind to clog the piping. But on a condensate drain line there is no sewage and no solid waste.
(July 22, 2011) Frank said:
I noticed leakage in my ceiling after a technician rewired my brand new conditioner to run at a higher fan speed which forced more air into my house. Made sense and now feels cooler. a few hours later is when I noticed the water leak. I went into the attic and can see that there is water in the catch tray but the kicker is that there is a small hole a couple of millimeters round at the end of the tray allowing the water to leak out into the insulation down the roof into my plaster ceiling. What in the world is a hole doing in my catch tray?
(Oct 23, 2011) Anonymous said:
try a diyvac wet vac attachment to unclog the drain line .The attachment fits on the wet vac and drain line perfectly and takes a couple of minutes to unclog once vacuum is turned on.
(May 31, 2012) jay said:
water is coming out the top of my ac furnace
Jay, if your unit's condensate drain pan has begun to leak, or if its drain is clogged, those would cause the leakage at the air handler as you described. There should be a removable panel to give view inside the unit to see the condition of the drain pan itself.
Watch out: water leaks onto a heating furnace heat exchanger can cause rust and dangerous heat exchanger leaks - risking carbon monoxide poisoning.
(June 26, 2012) Remo said:
Hello, it looks like my condensate drain goes directly from the ac unit down to a nearby bathroom sink and connect to the p trap. there is no way to pour bleach suck with a wet vac. when the AC kicks on, there is a horrible gorgle sound out of our bathroom sink, how can i fix that?
Remo, it sounds as if the drain tubing needs to be disconnected and cleaned.
Dan, i think you are right, but how do we disconnect it? at what point, mid way? at the AC
I'd start by trying to get inside the air handler (power off) to find the opening into the drain, and to brush clear the trap if one is present.
(July 7, 2012) M12451 said:
My ac runs but water fills up at the bottom where the condensation pump is located, I not sure what do. Can someone with good expertise please advise.
Thanks Not a HOT Summer
It sounds as if either the condensate pump switch or the pump itself needs replacement
But first be sure the condensate pump is plugged in and has electrical power
(July 17, 2012) Ann Borg said:
Our condensate line backed up causing a wet drywall and ceiling....because the builder was too cheap to install an over flow valve. It has been corrected and all of the information on your website was excellent. Thank you.
Ann, sorry to read of the condensate backup - but what "flow valve" are you referring to? It is common to drain condensate by gravity when possible, and it is also not uncommon for the condensate drain trap or line to clog with lint and crud - it's a maintenance item. Can you tell us what valve you mean? Do you mean a condensate overflow tray sensor switch?
(July 27, 2012) Jennifer said:
Hi Our 2 units have only one drain line and it seems to leak. What is the code that each line should have their own independent line?
Jennifer, none that I know about. But the condensate drain does need to be large enough to handle the condensate flow rate without backing up; if your condensate line is leaking I suspect either it is clogged or there are improperly made leaky connections.
So if one has this issue, do I call an HVAC technician or a plumber?
Start with your HVAC tech. who may have just the right sized tools to clear the condensate line clog. But some problems such as a clogged condensate line or a broken condensate pump are within the scope of others such as a plumber, handyman, and many homeowners.
(Aug 25, 2012) Rich said:
I noticed yesterday that there was water coming through the ceiling and suspected it was the A/C unit. When I got into the attic there was no water in the drip pan or any evidence that it had been wet, and the drain lines were not clogged (did the water/bleach test and drained properly).
I opened up the unit which held the refrig evap and that inside drip pan was full and I suspect overflowed into box where the ducting is connected. The liner is soaked as well as one ducting had a puddle of water. This is where the damage to the ceiling came from. Do I have a bad refrig evap unit or bad drip pan inside? My first thoughts were we just recently had a lot of humidity and the drip pan couldn't keep up... Thoughts? Thank you!
(Sept 9, 2012) Samantha said:
I'm noticing water dripping from the bottom of our air handler onto the floor (1st story, closet installation). I'd like to clean out the drain pipe as I'm guessing there is a clog, but there isn't any access point - should I just attach a wet vac to the outside pipe and vacuum it out? Our house came with a heil unit and I can't find anywhere to even open it up to view the drain pan itself.
To answer this we need to look at the drip pan to see if it's clogged, rusted, perforated, leaking, overflowing, or if there is a problem with the condensate drain piping. Start at the unit.
Tom Kolter said:
You should check out the Jones Valve, too, available at Supco and Watso, United Refrigeration and Johnstone, the latter two as "Line Drive".
(July 13, 2014) Altin said:
the top ac drainage is leaking, also the bottom. what is the risk and what should I do?
The risk is water damage to the equipment - depending on where condensate is flowing; other risks include mold or other water damage, or bacterial contamination such as Legionnaire's disease.
YOu want the condensate pan fixed if it's leaking, the drain un-clogged and flowing.
Re-posting a reader's comment without disallowed link:
Never Cut Or Pull Apart Drain Lines once the ALL-ACCESS AA1 is installed.
It provides easy access to clear and maintain drain lines using any method.
Please take a look at allaccessdevice dot com to learn how it works and where it is sold.
Stuart refers to a fitting that is added to the condensate drain to permit drain line cleaning by attaching compressed air, refrigerant, or possibly a vacuum.
Watch out: this fitting and its use may be inappropriate for condensate drains connected to plumbing system piping. - Ed.
26 Dec 2014
I have a concern about biased product placement in the above article.
Thanks to reader Stuart Oakner for suggesting additional discussion of the Mighty Pump as a less costly way to clear blocked air conditioning or heat pump condensate drains than calling the HVAC service technician.
But, he is the owner & salesman behind both the Mighty Pump and the All-access device. There should be an editorial policy of not allowing product inventors/sales reps or whatever to influence the placement of their own products whether they're professionals or not, at least not without an explicit disclosure.
You can see his affiliation here [references deleted for privacy] - I.H.S. [email on fiile]
Thank you for informing us of this. It's a first to have been surprised with a sneak product placement. We will review and edit the document accordingly. Perhaps you could also identify yourself?
I came from another web forum and noticed this guy show up and started pitching his product using third person voice. A web search led me to discover that he's doing the same thing on your site. That's how I stumbled into your page and decided to drop you a line. I think that is enough :)
(Aug 16, 2014) john said:
I have water dripping from my secondary drain from the airconditioner in the front of my house. The pan is full of water under the unit. I sucked the primary line open with a wet dry vac. My son can hold his hand over one end of the primary drain pipe and get good suction to his hand when i am sucking with the wet dry unit on the other end. The primary line is clear. The pan is still filling with water. Can there be a blockage inside my unit that isn't allowing the water to flow out of the primary drain? How do I clear that?
If the secondary or "overflow" condensate drain pan contains condensate then either there is a leak into the pan allowing condensate to leak out of the air handler or its primary condensate handling system, OR the primary condensate handling system is inoperative - typically because of a blocked pan drain opening or condensate drain line trap. YOu'll need to shut down the system, open the air handler, examine the drain for leaks or damage or debris, clean it, and beginning there follow and clear the drain path.
(Aug 28, 2014) Anonymous said:
on a Electrical split heat-pump system does the p-trap on the condensation-line create a vacuum to remove the condensation from the unit ? Presently the condensation line is broken and has been detached directly at the air-handler unit, but condensation water keeps getting over into the Fan-half of the unit therefore drawing moisture into the house.
Anonymous :-) by the way the air handler is in the crawl space . . good thing huh!
P traps do not create a vacuum nor suction to remove water from a condensate drip pan or HVAC unit. They are there to prevent backflow of gases into the unit from the drain line.
Don't spill water in the crawl space: it's asking for a mold problem.
(Sept 10, 2014) Cost said:
What should it cost to have someone come out and clean the A/C water drain?
Typically a single hour (minimum) charge service call from your HVAC company or plumber will suffice, but of course that depends on variables such as
- ease of access to the equipment
- the diagnosis of why the AC condensate (water) drain has logged
- whether other clog-related repairs are needed
we include examples of what can go wrong with the simplest plumbing job that can result in higher costs.
(Oct 15, 2014) Anonymous said:
SO what IS the quickest, easiest way to clear a blockage?
(Nov 5, 2014) Ben Stevens said:
[ put Clorox and vinegar in the drain line on the heat pump, now I have a bad smell and burning eyes. how do I clean it up or ixit up?
(Nov 5, 2014) ben firstname.lastname@example.org said:
can I replace the drain line and the smell clear up?
If a clogged, leaky condensate drain was the cause of odors, clearing it or repairing it or replacing it ought to be the ticket. But from just your question, I can't say what's going on.
Blockages are cleared mechanically, by vacuum cleaner, by air pressure, or by line replacement (least common).
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