Photograph of  improper condensate drain connected to plumbing vent line A/C or Heat Pump Condensate Drain FAQs
Q&A on HVAC Condensate Drainage

  • CONDENSATE DRAIN FAQs - CONTENTS: questions & answers about Air Conditioning condensate drains and their proper routing, installation, traps, slope, connections & installation.
  • POST a QUESTION or READ FAQs about air conditioner or heat pump condensate drain installation, leaks, clogs, troubleshooting, repairs
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A/C condensate drain questins and answers:

Q&A on condensate drain or condensate disposal codes, installation, leaks, clogs, connections, troubleshooting & repair.

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A/C or Heat Pump Condensate Disposal Drain FAQs

Condensate disposal locations (C) Carson Dunlop Associates

Carson Dunlop's sketch (left) shows the proper locations for disposal of air conditioner or heat pump condensate.

[Click to enlarge any image]

Notice that one of the most common condensate disposal locations, connection to a plumbing stack vent pipe, is not recommended and is prohibited by building code in some jurisdictions.

These questions & replies were posted originally at CONDENSATE DRAINS, CODES - topic home.

On 2017-07-24 by (mod) where does the condensate go? Retrieving a ring.


I'll be glad to help but I need do understand more about what we're dealing with here.

If the ring was dropped into the open top of a vent on a condensate drain pipe you should see a trap - a u-shaped bend in the pipe - just below the vertical pipe. If so you can probably fish out the ring with a wire with a small hook bent into its end.

Take care not to push the ring past the trap or you may need to cut the line to retrieve the ring.

If it'll help you can use the page bottom or top CONTACT link to send me photos of the system.

On 2017-07-24 by Divya Negi

If anything trapped or put into HVAC where should it go? I suspect my little one has put a gold ring into it.What is the best way to look for the placed object into it?

On 2017-07-14 by anthonydefex

From Brooklyn, NY. I have the a/c water discharge pipe coming out 5 inches, straight out, horizontally, from the wall and about 20 feet above ground. The a/c unit is on the roof. I'm on a 3rd floor apartment. The water lands on a concrete floor in front of the building that's only 1 foot deep (from the wall to the outer side).

Beyond the narrow concrete stretch is a soil surface garden area. The area where water falls is not a normal walking area, people don't need to walk there, and there is no damage on the ground where the water falls. This setup was installed in 2005 by the previous unit owner.

The new management is requesting that I extend the pipe out so that the water falls on to the garden because the water is "attracting birds and insects", "keeps area wet all the time", and "creating algae" I wanted to know if there is really an issue at all that needs correction?

If the pipe can be extended, by how much so? Will the extended pipe cause the water to spray more around causing an issue?

On 2017-06-20 by George

How do I install pvc condinsate drain line properly from suspended ac unit

On 2017-06-16 by Paul S

Lowes floor installers installed flooring over the condensate drain. Geosprings heat pump water heater. Water droppped on floor, under baseboard, black molding, flooring gone, flood cut on drywall. Thousands in damage. Just happened. Am now proceeding against Lowes. Insurance company clause is that seepage must be reported within 14 days.

Concealed damage not a waiver. So I am proceeding directly against Lowes.

On 2017-05-31 13:22:26.913690 by (mod)

No, but I certainly would like to see some photos if someone has tried to do that. Are contact Link at page bottom includes an email

On 2017-05-31 13:00:02.951883 by Trey

Do you have to have a trap between your air handler and a condensate pump

On 2017-05-31 12:58:53.791362 by Trey

Can you use a little giant condensate pump as a trap

On 2017-03-31 22:59:06.626364 by (mod)

I'm doubtful that this is a good approach. First I want to see an air gap between the condensate discharge and the drain into which it is discharging. I'm doubtful that you can do that when you pipe horizontally through wall into a plumbing trap at and adjoining units sync. II there maybe liabilities as well as actual hazards for the documents from a leak or from bacterial hazards.

First I want to see an air gap between the condensate discharge and the drain into which it is discharging.

I'm doubtful that you can do that when you pipe horizontally through wall into a plumbing trap at and adjoining units sync.

Also there maybe liabilities as well as actual hazards for the occupants from a leak or from bacterial hazards.

On 2017-03-31 12:41:53.653019 by Garrett

I am working in a multiple unit apartment complex. Can i drain a condensate line from a common area to a lavatory tailpiece in a private unit?

On 2016-10-05 23:58:43.579591 by James tomsen

Is it against code to drain Condersate for mini split A/C system onto a concrete patio

On 2016-09-16 14:53:59.644044 by (mod)


One can joint condensate drains to a common one if the drain slope and diameter are adequate to handle the flow rate. I'm not sure how the tankless water heater is involved in the discussion.

On 2016-09-16 03:51:38.582942 by Slava

Can I conect three primary condensate lines together?
And I like to connect three secondary condensate line together as well?
Do I need to increase the size of the pvc pipe or it can all go in to 3/4" line and out?
I have two FAU units and one tankless water heater all in the attic in the sale locations.

On 2016-09-08 18:34:11.390933 by (mod)


It sounds believable. The condensate from a fossil fueled heater is likely to have been acidic and thus corrosive. But another factor is just what type of copper piping was used for the drain; thin-wall copper piping material may be less reliable.

See LEAK CAUSES in WATER PIPING for more about corroding copper piping.

On 2016-09-08 by dave

We had a copper pipe from our natural gas burning ac/heater condensation pump to an appropriate drain.

The pipe deteriorated and leaked in several locations.

The HVAC installer came out and replaced it with clear tubing. We also have a heat pump that still has a copper drain pipe that the HVAC installer states is fine as it is not from a fuel burning appliance and will not corrode/leak. Does this sound right?

On 2016-08-30 by (mod) a way to tap into the water flow to drain it off into a bucket and use it to water my plants

A/C condensate, particularly when stored, risks brewing pathogenic hazards such as Legionnaire's disease.

It would be better to use the condensate for watering plants than to keep it in storage, where it certainly would not be safe to drink without various filtering and disinfection steps. I suggest asking your local health or plumbing inspector for an OK letter that includes a tap to permit use of condensate for plant watering.

On 2016-08-30 by rahur

We live in an area of frequent severe drought. The condensation water is currently running down the wall into a large (56 qt) storage bin, which fills up frequently when humidity is high and we are running the a/c a lot, that is, when it is very hot outside. Which is just when we are forbidden to water more than once/week and the plants need water the most.

When the contractor puts the outside downline in, I wanted a way to tap into the water flow to drain it off into a bucket and use it to water my plants. Something like a special faucet perhaps, but nothing that will blow the integrity of the line.

They say that is illegal, but they have told me this on other things and when I have researched it, what I wanted was just fine, even ok'd by the head of the city inspectors' dept. I don't really know where they are going to take the water, but it seems a hideous waste to just pour it into a sewer when we have such an enormous need for water right when this condensate is most likely to be in high volume.

I am 70 yrs old and so not going to be lifting heavy things, but a couple of buckets and a rolling carrier and I can take the water wherever it is needed, a cpl of loads per day -- if I can get at it when I want to.

Do you have any ideas how this could be arranged -- legally and safely?

On 2016-07-15 by (mod) why not dump condensate into a foul water drain?

A guess would be concern for backdrafting of unsanitary or explosive sewer gases into the building through the air handler.

On 2016-07-15 8 by Ian Pyett

Why in the commercial industry are you not permitted to discharge a/c or fan coil units condensate into a foul water drain only into rainwater drains?

On 2016-06-11 by (mod) Can you use electrical conduit as a drain condensate pipe ?

Well, no I doubt it. Electical conduit is not designed for nor rated for use as a liquid drain line; also, its connectors are not water tight unless you're using outdoor conduit.

On 2016-06-09 by Joe

Can you use electrical conduit as a drain condensate pipe ? If not could you say why ? Thanks in advance .

On 2016-06-03 by (mod) code for protecting condensate line run through studs

Bill I don't have a clear understanding, and I doubt building codes specify exact methods of securing condensate lines but rather will require proper slope and support at intervals that depends on the line material.

For example flexible conduit drain line is very saggy and risks clogging, bacterial growth, and backup where if/where it sags between studs.

You don't say what caused the holes - nail punctures or something else.

Good that you found the problem. Be sure the line is sloped 1/8" to 1/4" per foot and supported without sags, and protected from puncture. Search InspectApedia for CONDENSATE DRAIN PIPING to read details.

On 2016-06-03 by Bill

We have water on the floor and after opening the wall we found two small holes in the drain line causing the problem. This line was not attached to the stud and is 1.5 inches to 4 inches from the stud is this correct by code?

On 2016-06-03 by (mod) Mitsubishi Mr. Slim Split Air Conditioner and Heat Pump System condensate disposal vs mice

Anon I would not blame the manufacturer for a mouse problem; I'd clean up whatever food is attracting the mice, use services of a mouse exterminator, fix the AC wiring and seal the mouse openings.

On 2016-06-03 15:57:17.235380 by Anonymous

I purchased 2 Mitsubishi Mr. Slim Split Air Conditioners and Heat Pump Systems two years ago.

One unit stopped working and it was discovered that mice had chewed the wires in the outside condensers because these units have a 1 ⅝” manufacture installed drainage hole.

With holes this large, many animals are likely to venture inside. I need to purchase another air conditioner unit but am not going to buy another Mitsubishi because of this issue. Do all mini splits have such a large drainage hole in their units?

On 2016-04-08 by (mod) what is the clearance between the condensate pipe and the roof

John, usually the refrigerant lines are run in or on the attic floor, but if you need to run them under the roof, I'd follow the same guidelines as for electrical wiring: that is, you either mount the lines to the interior edge of the rafters or if you must run a line through a rafter you'd drill the passage hole in the *center* of the framing member.

That minimizes any impact on structural strength of the member and also should be deep enough or far enough from the roof surface to avoid a nail puncture.

Finally, if you must run refrigerant tubing or a condensate line or a wire or pipe of any sort through framing where its location exposes it to a nail puncture, you must protect the tubing etc. from puncture by using a nailing plate.

See on installing refrigerant piping or condensate lines,

and also

On 2016-04-07 by John

What is the code on running a/c lines in attic what is the clearance between the pipe and the roof (plywood) so roof nails cant penetrate lines in Florida thank you

On 2016-03-23 by (mod) How far does this pipe need to be insulated?

I'd insulate where needed to protect from freezing and to protect from exterior condensate forming on and dripping off of the line into a problem area. If none of the line is exposed to these conditions none of it needs to be insulated.

On 2016-03-23 by james

So my ac guys are running the condensation drain pipe through a hanging ceiling. How far does this pipe need to be insulated?

They are telling me only ten feet from where it drops in through the roof, however I was told it needed to be insulated all the way to the drop down at the wall where it would then tie into the sink drain. Please advise. Thanks

On 2016-03-07 by (mod) Do condensate drain pan and elect. cut-off codes apply to a replaced air handler?

Ted I may be missing something, but I'm not aware of any instance in which building or electrical codes apply different rules to replaced HVAC equipment than to original equipment.

On 2016-03-07 by Ted White

Do condensate drain pan and elect. cut-off codes apply to a replaced air handler?

On 2015-10-17 by Anonymous

I purchased a totally new American Standard 824 GoldXV in Texas-hot and humid about a year ago.

I recently had leaks flowing from ceiling where the unit is located in the attic as well as dripping outside the window where the drainage pipe drains away from my foundation.

Should these connections have been secured upon installation? AC company is saying this was not included upon installation.


On 2015-10-03 by brett

Installing a condensing furnace in a crawl space. Horizontally on a slab, there is no room for the factory p trap. Is there an alternative?

On 2015-09-29 by Mike

Hi. My daughter bought a house a little over a year ago in NC. One side of the house has rust stains from the drain pipe coming out of the siding. Long story short, it looks like the AC Drain system was installed backwards. The main drain from the unit goes thru a pipe and into the drip pan which fills and empty's from the top level onto the siding.

Over the year, this water turned the galvanized drain pan rusty and that is what drips onto the house.

The emergency drain for the AC goes thru the attic and outside next to the compressor. Of course, that line is dry since it is hooked to the backup.

Does this meet code or does the code specifically say that water should only go thru the drip pan as a backup/emergency?
Thanks for any advice.

On 2015-09-02 by (mod) East Texas code on home made seepage pit for condensate disposal

Sorry to duck and weave and arm-wave but the truth is your local building code compliance inspector is the final legal authority on a question such as this.

Some jurisdictions don't permit any wastewater discharge to the ground surface but might buy discharge into a seepage pit.

My OPINION is it sounds as if someone made a home-made mini seepage pit intended only to catch A/C condensate. The worry would be a fatal Legionnaire's disease bacterial infection that might occur IF the condensate drain is not properly piped and trapped.

On 2015-09-02 by Roger

I have an old AC drain through the slab which terminates outside underground at what looks like a 5-gallon bucket turned upside-down over a gravel bed with no cleanout access. Is that and acceptable discharge system in East Texas? If not, what would be better?

On 2015-08-22 3 by Confused

yes they are both 3/4". Thank you very much for your help, it is greatly appreciated!!

On 2015-08-22 by (mod) where to connect condensate to the drain

you can if the second line is of adequate diameter

yes the top

or you'd need a check valve in the pumped line

On 2015-08-22 by Confused

I have 2 fan coil unit condensate lines draining to a floor sink, however 1 of them needs a pump because of obstructions.

So once the line comes up over the obstructions can I connect the pumped condensate line into the sloped condensate line from the other fan coil unit and if so does it have to connect to the top of the sloped line?

On 2015-08-07 by (mod) why is condenate dripping out of the fan coil unit and onto on the apartment floor ?


Typically the condensate pans are clogged, missing, leaking, improperly installed, or the condensate drains are clogged as discussed in the article above.

On 2015-08-07 by Anonymous

In a 34-unit apartment building, why does condensate drip on the floors from most of the apartments' fan coil units?

On 2015-07-29 by (mod) OK to drain the condensate in a crawl space?

I would not dump AC condensate into a crawl space. The risk is elevated moisture, mold contamination, and contaminants entering the building.

I'd make an exception IF the condensate were pouring directly into a sump pump or other pump that is disposing of the water outdoors or to a sewer drain.

On 2015-07-29 by Charles

Is it OK to drain the condensate in a crawl space under a house

On 2015-07-17 by (mod) recurrent condensate drain clogs

The reason for recurrent clogs in the condensate drain system needs to be found and corrected.

Regular use of drain cleaners or any other un-stopping material is not a good substitute for proper installation and design of the condensate system. I suspect there is a piping problem: routing, slope, diameter, distances, termination points, or possibly failure to trap condensate drains and screen against lint or debris entering the system.

The condensate sensor switch that shuts off your system can be wired to shut off others too, or if necessary multiple switches each sending to an individual AC unit can be mounted in the same sensor location.

On 2015-07-17 by Bob Collidge

I live on the 2nd floor of a 4 story condo. The PVC condensation pipes of the 2 units above me and the unit below me connect to a common area vertical PVC pipe (presumably dedicated to condensation disposal). We periodically pour vinegar into individual unit pipes to keep them clean but it's not preventing clogs in the common area pipe.

A water detection device will shut off my AC if it detects a backup but it won't shut off the AC of the units above me, so it still backs up into my unit.

Any suggestions on how to do preventive maintenance on this system? Thank you.

On 2015-07-09 by (mod) condensate line slope, gfci powering pump trips, Georgia

Slope: 1/8 to 1/4" in 12" of run.

Ask an electrician to check the receptacle. Often GFCI's in damp places will trip. You may want an exception to GFCI code for the pump application.

On 2015-07-09 by Pauol Louden

Twice this summer here in Georgia, the GFI receptacle that supplies power for the condensate pump has tripped. Agreed it's very humid during the summer in Georgia. How do I determine if the receptacle is going bad or the condensate pump is going bad?
My AC is located under the house in the crawl space. Another solution would be to run a drain pipe directly from the AC to the outside.

What slope is required for this?
It bothers me that if I went on vacation during the summer and the receptacle or condensate pump failed leaving humidity to build up inside the house.

Being a former worker in the environmental industry, I know it isn't cheap to remediate mold/mildew.
Please send answer to

On 2015-07-05 by (mod) condensate drain should be trapped

The condensate drain should be trapped, Steve.

On 2015-07-05 by Steve

I live in a new ground floor apt. the A/C condinsate drain goes into a floor drain along with two upstairs units , the waste goes into a 4 inch open drain and the pipes go in about 1.5 inches with no air gap.

Is within code? The drain is behind the water heater out of sight so I crawled in and took pictures....

Question: questions why it's not advisable to pump condensate into a sewer drain

(Mar 16, 2014) Anonymous said:

why would a condensate pump line into a drain be a problem when the pump has a check valve which allows no back leakage of gas or water and if the drain ever clogged, it would back up either way anyhow

Reply: Little Giant condensate pump

Interesting question Anon. A great many, possibly more than half HVAC condensate drains do not involve a condensate pump nor any check valves, just gravity operated drains.

I'll be interested to know more about the condensate pump check valve to which you refer and if they are universally present in condensate pump systems and if they are considered adequate to prevent back contamination by both dangerous methane gases and by bacteria who don't have much respect for mechanical devices.

A quick check shows that the Little Giant condensate pump is available with an *optional* extra part - the CV-10 check valve that can be added to the condensate pump itself - it's not an integral part of the condensate pump. The Little Giant VCMX-20ULST does include a check valve.

The Little Giant VCMA Series can accept the add-on check valve provided by the company. So based on just a quick review, it would be incorrect to assume that a check valve is always present and even if present, that it's rated for sanitary concerns.

Question: ok to drain condensate into the roof guttter?

(Mar 23, 2014) Anonymous said:

Is it okay to have the condensation pipe running into the guttering ?



That's a common practice; whether or not it's ok depends on where the condensate ends-up. If it's running down a foundation wall into a basement or pooling where kids might play in unsanitary water that'd be a concern. If condensate is going to be produced and disposed-of in freezing conditions that may also be a concern. Otherwise, probably fine.

Question: OK to drain condensate into a DWV tub vent?

(May 4, 2014) peanut737 said:

if you run a condensate drainline to a dwv tub vent thats venting to the roof would it be safe to say thats its ok as long as there is a breather T and running trap at the a-coil right off the condensate drain. And what if you also put 1 1/2 trap right before going into the vent.



My OPINION is that while the volume of HVAC condensate water running down a dry vent is unlikely to cause improper drain performance, in general plumbing codes don't want us to discharge water into a "dry" plumbing vent design.

I surmise you are proposing an air intake that would prevent negative pressure in the air handler from drawing sewer gases back up the condensate drain into the duct system. That sounds to me like someone inventing a solution to a possible problem (sewer gas induction into building air), and it might be a good idea.

But we ought to either research to find that such a solution has already been designed and tested and approved, or we ought to propose that invention and invite expert testing.

I suspect that the occurrence of unsafe back-drafting of sewer gas into the air handler is rare, but that it has occurred enough to raise industry and plumbing code concerns. We might be looking at an uncommon event that we still avoid because should it occur the consequences could be serious.

Traps and vents and air movement that can siphon the trap can subvert its function - that is cause it to run dry and not work as a trap.

Question: sorting out mysteries of a clogged condensate drain line

(July 7, 2014) mtarnett1983 said:

We bought a house over a month ago. About 2 weeks in, I noticed a bad smell coming from the duct system.

Then I heard dripping, when I pulled the vents down, I found about an inch of water on the bottom of the floor under the air handler. I wet vacked it and cleaned it up. We then cleaned the coils, wet vacked the primary drain line several times and also poured a water/bleach solution through it.

We had to have Freon added to the a/c. Been cooling fine, but have noticed in the past week, the primary drain running from the air handler to outside of house is not draining any water outside. Three days ago, I found water coming down the edge of the foundation and brick, below the condensate line outside.

We poured water again through the primary drain from the air handler to the outside and it flowed through just fine, but no water will come out that drain from the condensation.

Today, I wet vacked again from the outside and pulled about 3 gallons of water out.

Does anyone have any idea why you can pour water through the line and it flows outside with no problem, but the air conditioning when producing condensation, will not flow through the line but instead, pool at the bottom of the concrete slab of our home below the drain line? Any help would be soooo appreciated!

This is also a gravity fed primary condensate line, it does not have a condensate pump.

One other thing, it does have a secondary line, however, when I found the water pooled below the air handler, it did not flow into the safety switch box, it was all around it. We assume that was from how dirty the coils were. We checked the P-trap and drain pan and did not find any holes in it.


The condensate must not be entering the drain line, right?

Reader: mtarnett1983

Right. When we pour water at the top of the drain line inside by the air handler, it flows right on through to the outside of the house.

However, when the a/c is running, as of a week ago, nothing is dripping outside of the drain line and water is coming out of the bottom of our concrete slab foundation. We just wet vacked the drain line outside again and got about 6 gallons of water.

The water coming out by the foundation is just below the primary drain line outside.

Since cleaning it a couple of weeks ago, it was dripping outside just fine. It stopped after we cleaned it one more time about a week ago.


Is the condensate pan sloped so that water enters the drain?

Reader: mtarnett1983

Yes. We actually poured water in the pan and it flowed into the hole just fine.

You can also tell that the pan is at a higher point inside the house than where the drain on the outside is. The primary drain flowing outside is about 12" from the ground and the primary drain at the air handler is about 3 feet above the ground. I don't understand why all of a sudden it stopped dripping outside. It was dripping just fine.

My husband also took a string and held it above the primary line under the air handler, I then took the wet vac and went outside and was able to suction the string all the way through to the outside. He said he wanted to try that to see if there was a break in the pvc from the air handler to the outside



I have on occasion seen droops, loops and sags in flexible condensate drain line installations, particularly in split-system AC installations where the drain runs through ceilings or walls. I had to open a wall and straighten such a line to keep it draining as the loop low points accumulated clogging debris.

Reader: mtarnett1983

This one isn't a flexible drain line though. It is pvc from the air handler to the outside. Maybe a 1" pipe with 3/4" opening? We have a concrete slab. I would assume the pvc is running just above the concrete slab through the house to the outside?

Would it be a bad idea to run a flexible line smaller than the pvc into the drain line starting at the air handler, all the way out of the house?

We were wondering if by doing so, it would drain through that line and bypass the pvc. We know when we vaccum the water from outside it flows out. Does the trap need priming? It's as if though it doesn't have enough pressure to pull it outside. When we pour water through it, it flows right through and goes outside.

Thanks Dan for any help you can provide! We are grasping at straws now.


If the pipe is unblocked (run a small snake through it entirely) and properly sloped it should be draining.
If there were a leak in its passage that ought not stop it from draining but rather would show up as a water leak in a wall or ceiling.

Traps don't need priming in a drain line, but it would make sense to be sure that the pan slopes to the drain, that the drain opening is not so covered with water that no air can enter the drain along with water (or it may drain poorly as will any plumbing drain), and also double check that your backup overflow drain or condensate pan switch is working lest you flood the building.

Reader: mtarnett1983

Thanks Dan. The pan is sloped ok. There's no water standing as it drains as soon as we pour water in it.

Do you have any idea why it would just stop dripping? It did it after we cleaned it out the third time with a bleach/water solution.

I guess what you are saying is it could have developed a leak somewhere in the drain line and gravity stops it from flowing outside and it pools just inside the wall of the house? Is that why when we pour water into the drain from the inside, it goes through to the outside fine due to it is a larger amount going through all at once?


Sure. Condensate may stop dripping under these normal conditions

-the AC has stopped running

- the AC continued to run but has successfully lowered the indoor humidity such that little condensation is occurring on the cooling coil.

Question: why so much condensate coming out of the system?

(July 8, 2014) Anonymous said:

If the AC is successfully lowering the humidity, why are we wet vaccing several gallons a day out of the drain line outside?

We started wet vaccing again the other day when we noticed so much water was coming out of the bottom of the foundation by the drain outside. Every day we are vaccuming the line several times and getting a total of about 7-10 gallons. We figured it would be better to try and get as much water out of the drain that we can so it doesn't pool behind the outside wall.


Agree - I was responding to possible reasons one may not see water coming out of a condensate drain.

In most installations the condensate drain system is not complex. I'd follow the water from its initial location on the cooling coil, into the pan, from the pan to the drain, through the trap, through the condensate drain to outdoors.


The bad thing is that the drain line is either installed in the concrete slab or right above it. We would have to either tear down sheet rock to follow it or break up our slab from the bottom of the air intake and then 23 feet to the drain outside.


Anon I'm certainly not advocating tearing up a 23 ft slab - by the way the long length of this run is NEW data in this discussion and invites speculation about easily clogged insufficiently sloped condensate drainage.

Before anything so heroic I'd install a separate condensate drain pump to dispose of the condensate without relying on the problematic drain system


I appreciate the information! I will research the information about installing a drain pump. Is that a DIY or should we have a professional do that?


If you are handy and will read the instructions it's pretty easy.

If the equipment is hard to access, I'd speculate that if the condensate drain, drain pan, etc are not present, or if wiring repair is needed, then in my opinion the original AC installation was incomplete and the installer should finish the job properly.

Question: do vibrations from the air handler cause condensate drain leaks?

8/20/14 Joelzingerman@yahoo,com said:

Our drain is made of PVCpipe. It had a crack and water leaked through the ceiling. they repaired the pipe and this weekend there was another leak onto the second floor ceiling. both AC units are in the attic. a repair man came found a hole in the pipe and installed a new section of pipe.

He went outside . Made a few other joints to the pipe and secured the pipes to the base on which the condensers rest. This does not seem proper to me. Wouldn't vibrations from the running AC possibly loosen the pipes somewhere where we would have further leaks. this is a newAC



I cannot say from just the information in your message what might be improper or not.

I agree that HVAC equipment vibrates.

But it is not common - that is we've not particularly had field reports indicating - to hear of condensate piping leaks from that cause. If the piping is the proper material, properly joined, routed, and supported it should be fine. Where I"ve seen failures usually they were due to failure to properly prep and glue joints or failure to properly route, slope and support the drain lines. Condensate line blockages are more common than breakage-leaks.

Question: causes of cracked leaky condensate drains: vibrations?

(Aug 20, 2014) Joelzingerman@yahoo,com said:
Our drain is made of PVCpipe. It had a crack and water leaked through the ceiling. they repaired the pipe and this weekend there was another leak onto the second floor ceiling. both AC units are in the attic. a repair man came found a hole in the pipe and installed a new section of pipe.

He went outside . Made a few other joints to the pipe and secured the pipes to the base on which the condensers rest. This does not seem proper to me. Wouldn't vibrations from the running AC possibly loosen the pipes somewhere where we would have further leaks. this is a newAC



I cannot say from just the information in your message what might be improper or not.

I agree that HVAC equipment vibrates. And I agree that depending on the piping material, location, proximity to and connection to vibrating equipment, extent of vibration, piping support details and routing, plastic piping could be cracked by that activity.

But it is not common - that is we've not particularly had field reports indicating - to hear of condensate piping leaks from that cause. If the piping is the proper material, properly joined, routed, and supported it should be fine. Where I"ve seen failures usually they were due to failure to properly prep and glue joints or failure to properly route, slope and support the drain lines. Condensate line blockages are more common than breakage-leaks.

Question: condensate drain connected to a building shell drain

(Aug 21, 2014) Damon Mitchell said:
Why is it i cannot find anything on the method of taking indoor condensate out of a building to a shell drain?


If by shell drain, Damon, you refer to a building exterior wall or shell drain opening such as brick veneer weep openings, that may be a risky business, particularly if the individual weep opening is not correctly flashed, if it becomes blocked, or if the extra volume of water in that location causes a backup and leaks or damage to the structure.


If you are talking about something else please let me know.


(Aug 22, 2014) said:
How do I send you a photo of the outside AC drain pipes

the drains were attached to the plastic base the condensors sit on. I'm concerned about vibrations loosening or cracking the pipes


Joe our email is at our CONTACT link found at the page top or bottom of any article

Question: damagbe from condensate ending at a brick wall

(Sept 7, 2014) Martha said:
Will a condensate drain line that terminates at an exterior brick wall cause damage to the wall with the water running down the wall? And is it legal to allow the drainage water from AC to run across the side walk to the street?
Your thoughts will be appreciated.


(Sept 7, 2014) (mod) said:
Martha the condensate may stain the wall or encourage algae growth but I'm doubtful about "damage" caused uniquely by HVAC condensate unless water is actually penetrating the wall or is soaking an area of soft porous brick that is otherwise not exposed to the weather:

- after all, the wall is also rained-on. But most communities do not permit HVAC condensate to drain across a sidewalk.

Question: condensate leaking onto slab under home

(Sept 22, 2014) Lucille said:
Is it normal for the condenser to leak and have a puddle of water dripping on to the slab under the unit.

We had mini splits installed and have had the company come back four times.

The upstairs unit was leaking through the siding. They kept coming to insulate. It is also leaking under the condenser and they say its normal. There is usually a large puddle. Please advise. Thank you.



it sounds as if you are describing either a condensate handling system leak or missing insulation that results in condensate forming on and dripping off of refrigrant piping somewhere in its routing.

Indeed sometimes one must look carefully to find the source of the leak first so that the proper repair can be made.


(Oct 24, 2014) Martin said:
Is it acceptable to connect the condensate drain line from a condensing furnace to the primary condensate drain line of the AC evaporator coil?


It's a common implementation; in fact some condensate pump containers include multiple input openings or knockouts.


(Jan 21, 2015) Terry Leonard at said:
show example of condensate drain directly into sewer line with p trap to prevent sewer odor backup.

(Feb 28, 2015) Henry said:
if I have two mini split ac units back to back on a wall - does the condensate line need to be 1.5" or can it share the same 3/4 inch line?


Henry you may be fine with a shared condensate line but I don't really know for sure: the answer depends on the anticipated flow rate which depends on the AC unit capacity, indoor humidity levels, and other variables. Check with the manufacturer.


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