A/C condensate piping, drains & pump questions and answers.

This air conditioning repair article series discusses the inspection and repair or un-clogging of air conditioning condensate systems, including Air Conditioning condensate drains, condensate pumps, and their proper installation as part of our review of condensate piping, traps, drains, condensate pumps, and the detection and hazards of air conditioning system condensate leaks in buildings.

Condensate leak health and safety concerns are reviewed.

Examples of Improper Disposal of Air Conditioning or Heat Pump Condensate Disposal

These questions & answers about troubleshooting problems with A/C or heat pump condensate drains were posted originally at CONDENSATE DRAIN PROBLEMS - be sure to review that page.

Our photo of condensate piping below a crawl-space mounted air handler shows another ugly condensate disposal method: dump it on to the dirt crawlspace floor.

See details of similar condensate dumping location hazards at CONDENSATE DRAIN to OPEN SEWER LINE

[Click to enlarge any image]

On 2019-07-30 by (mod) - warnings on testing the TPR valve; keep that water heater leak pan

Actually I'd leave that installation as it is, PROVIDED that the ends of the AC condensate drains are NOT immersed in the trap water - we want an air gap there.

You're right that TPR valve manufacturers and the manufacturers of appliances on which they're used all advise periodic testing by opening the valve.

It's NOT something to try on a Sunday Night when the plumbing suppliers are closed, as if the valve spits out a washer or otherwise jams internally and keeps spewing water you have to shut down the equipment entirely (as well as turning off its water supply).

Sometimes we can flick the valve lever as you did, OR tap lightly on the valve stem, and it will un-stick itself and close properly.

If there is the slightest doubt about a pressure relief valve's reliability it should be replaced.

E.g. if a valve has been dripping or leaking for a long time I've seen so much mineral scale form inside the valve body that it would no longer open in response to an over-pressure or over temperature condition.

Watch out: if as your photo suggests, there is a wall cavity that could flood from water heater leaks or drywall that could be wet, then there's a risk of water damage, mold damage, etc. from a water heater spill onto that basement floor; in that case it's better to have the drain pan just as it's shown in your photo.

On 2019-07-30 by Anonymous

Thanks for the quick response...I believe the pan is to code. Benefit I see is that if leaks occur they are better contained and can be directed to a drain. In this case the last part was not so well executed on.

Agree on the corrosion concern...

Regarding the relief valve, reading my WH manual, apparently you are supposed to exercise it regularly. Flicked it a few times and it seems well seated now but will check out what you mentioned.

I’ve attached a picture..[shown above] .if you have any suggestions please let me know

Thanks again

On 2019-07-30 - by (mod) -

ok to drain condensate into the water heater leak catch-pan?

Jeff,

That idea sounds reasonable but has a couple of concerns about which you can think, investigate, comment further.

1. Mold & bacteria hazards: There must be absolutely NO standing water left in the overflow pan from condensate draining into the pan. Otherwise you risk growth of harmful mold or bacteria such as the legionnaire bacteria problem associated with AC systems.

Legionella BACTERIA & HVAC EQUIPMENT has details.

2. Water heater rust damage risk: Depending on the support under the water heater that keeps any metal parts off of the overflow / leak pan surface, if the pan is kept constantly wet with A/C condensate there could be rust damage to the water heater bottom.

3. Leak catch pan may not be needed at all: auxiliary drain pans with a separate drain placed under certain applinaces like water heaters and washing machines are required by some building codes specifically where damage to building components could occur as a result of water overflow from the equipment.

When a water heater is in a basement next to a floor drain and sitting on a concrete floor that slopes to the drain, I'm unclear what benefit is offered by the spill pan under the water heater.

Spill pans are placed under water heaters and washing machines when they are installed on an upper floor in a building, principally to catch what should be very rare leaks or spills in time to prevent them from damaging finish flooring in those areas. It sounds to me as if somebody just took a generic " install the pan " approach without much thought. Or perhaps a local inspector demanded it.

It may make more sense to simply remove the leak pan given it's not contributing anything in your installation and to keep the AC condensate's location draining right into the floor drain.

4. Unsafe Temperature / Pressure Relief Valve? The real danger here that hasn't been addressed is the stuck-open TPR valve.

The concern is that the valve may not function as it should in response to a true over-temperature or over-pressure condition, risking a dangerous BLEVE explosion of the water heater.

See BLEVE EXPLOSIONS to read details

So it may make sense to replace the TPR valve and to assure that it has a proper extension pipe

On 2019-07-30 by Jeff - running the condensate drains into the pan and the HW pan to the drain

My HVAC condensate has two pipes draining into a single 1.5” floor drain in my basement.

HW heater installed a few years ago and does have a drain pan. Unfortunately when the TPRV stuck opened last week we realized that the drain pan just spills on the floor a few inches from the floor drain. Likely because there is no room in the drain.

So I was thinking of running the condensate drains into the pan and the HW pan to the drain. Logic is that if the WH fails there will be a lot faster flow so I want that to flow directly into the floor drain.
So, what are your concerns with the condensate going into the WH pan? Other suggestions?
TIA

On 2018-08-03 by (mod) - can an ac unit condensate be plumbed into a water heater pan ?

Doug

I can't say that your suggestion sounds good to me: how is the water heater pan drained? Or is it drained at all? And doesn't such a design invite growing pathogens in the dust and debris that accumulate in the overflow pan?

On 2018-08-03 by doug

can an ac unit condensate be plumbed into a water heater pan

On 2019-07-28 by (mod) - condensate drains to bathtub

Brian

No; A/C condensate could be unsanitary, unsafe, for example possibly containing legionnaire's disease-causing bacteria. See Legionella BACTERIA & HVAC EQUIPMENT https://inspectapedia.com/aircond/Legionella_Prevention_HVAC.php

The condensate drain ought not be spilling into a plumbing fixture where it can come into contact with a person.

On 2019-07-28 by Brian

The condensate drain in my daughters apartment drains to her bathtub. In fact hits her right between the eyes when when is soaking. Is this legal of even acceptable practice.

On 2019-07-21 by Anonymous - The threaded fitting on the main condensate drain port have broken

You should be able to remove the broken fitting and replace it.

A photo would help.

On 2019-07-20 by Val

The threaded fitting on the main condensate drain port have broken. (The threads where the drain line attaches to the AC unit located in ther attic to. route the water outside) The fitting allows the 3/4 in PVC drain line to attach top the unit
The drain line now leaks at that attach point.
How would I fix this?

On 2019-06-07 by Airco Tech - p trap was sweating in attic by air handler.

Split system AC residential, Failed inspection for un insulated p-trap...p trap was sweating in attic by air handler.

On 2019-06-06 by (mod) - AC drain line is directly above my kitchen sink

I would not expect a plumbing inspector to have passed the installation that you described for your AC condensate.

Draining condensate into a sink where food is prepared is unsanitary and unsafe.

On 2019-06-05 by Anonymous

I live in apartment complex and the AC drain line is directly above my kitchen sink I was wondering if that is a legal hookup it drains into my sink but misses gets a counter splashes everywhere

On 2018-08-03 by Anonymous - drains to a mop sink or to outside building

not sure but probably drains to a mop sink or to outside building

On 2018-08-03 by Anonymous

not sure but probably drains to a mop sink or to outside building

On 2018-08-03 by (mod) - can an ac unit condensate be plumbed into a water heater pan

Doug

I can't say that your suggestion sounds good to me: how is the water heater pan drained? Or is it drained at all? And doesn't such a design invite growing pathogens in the dust and debris that accumulate in the overflow pan?

On 2018-08-03 by doug

can an ac unit condensate be plumbed into a water heater pan

On 2018-07-24 by (mod) - diagnose the condensate drain leak or spill trouble before trying a "fix"

Anon

First let's be sure we've diagnosed the cause of a problem with condensate drainage:

- leaks in the system

- drain pan does not slope towards drain

- drain is clogged

- drain trap is missing, improper, unsafe

- drain destination is improper, unsafe

You suggest that you have to lift the whole unit to add a shim to cause the condensate to drain. (the 2nd item in my little list)

But you say that you've had problems clearing the primary drain.

I'm unclear how a slope problem is causing the primary drain to clog.

The cost sounds so high that I'd want to be sure that we have the right understanding of the problem before spending the money.

I don't know what the second tech meant, but certainly the condensate drain MUST slope downwards 1/8" to 1/4" per foot from its trap to final destination or it'll certainly clog. If that's the issue, lifting and tilting the unit and its condensate drain pan isn't the right fix, it's fixing the drain line itself that's needed.

We should be able to diagnose this easily by looking more closely to see where the backup is occurring: in a drain pan that flows condensate over some edge or leaks out of a cabinet instead of draining towards the condensate drain trap
OR
a condensate drain line that clogs and backs up

If the latter, try first having it blown out.

On 2018-07-24 by Anonymous - ongoing problems with condensate drainage

We have ongoing problems with condensate drainage. System is 12 years old. In last 2 or 3 years extensive efforts to clear primary drain have not solved the problem.

Secondary drain has so far handled the drainage. Lastest theory on a proposed fix is to lift the unit enough to place a shim under one end to restore gravity flow.

Estimated cost is $1;500. Is this a reasonable approach (forgetting the cost)? Another tech suggested there was an issue with the drain pipe installation having to do with a riser.

On 2018-05-16 by Kari

Thank you! I don't have a proposal since I just found this out but I guess I need to contact a plumber. Thank you

On 2018-05-16 by (mod) - Condensate, like any wastewater, flows by gravity downhill

Condensate, like any wastewater, flows by gravity downhill - or down-slope. If a pipe drops down out of your air conditioner air handler then aims uphill it will either not drain at all (depending on how high it runs) or even if it drains, it will always hold condensate inside the pipe - inviting bacterial growth and thus potentially contaminating the air handler.

When we add that there is no trap back at the air handler there is risk of sucking droplets of contaminated water back into the air handler when the blower runs.

It's a poor installation, easily fixed either by rerouting the piping or by adding a condensate pump and a trap at the air handler.

You are welcome to let me know what's proposed to you or to ask further questions.

This should not be a big repair. It's trivial plumbing.

On 2018-05-16 by Kari

Thank you! I guess I need to hire someone because it doesn't make sense to me lol. I am worried , been ill stomach bothering me & my Husband recently passed away similar symptoms.

The system is electric but pipe goes into floor & I guess foundation but not sure
Thank you for your help. Karkens@aol.com

On 2018-05-16 by (mod) -

I would not be ***Very*** concerned, but I would want the condensate line properly trapped and routed so that it slopes continuously from exit to drain point. If you can't do that by gravity then you'll want to install a condensate pump.

On 2018-05-16 by Kari

@Kari,
Please respond about updated pictures I sent . I'm very concerned , haven't been well. Do I hire a plumber or hvac technician to correct the problem?

Should I send you a better picture if I can?

On 2018-05-16 by (mod) -

I really can't see most of oyur AC condensate drain system, Kari. But back up under the unit it looks as if the drain line angles up-hill: I'm not sure how that's going to work without leaks.

And of course there's no trap on your condensate line.

Doesn't look "correct" to me.

On 2018-05-16 by Kari

Could you please tell me if the drain for my hvac system is correct - photos above.
Thank you

On 2018-01-18 by (mod) - What is the correct height of a condensation drain line hanging over a floor drain? Is it 1" or 2"?

Jose

I don't think that height difference is substantive. 1-2" is OK.

Sean

Where freezing is a concern, and assuming your system will be producing condensate during cold weather, I'd prefer to intercept the condensate indoors at the air handler, where I'd install a condensate pump to send condensate to a suitable indoor drain or outdoor disposal point having routed the piping through heated space.

If you have to run that through a freeze-prone crawl space you may need to use a heating tape.

Note that current best practice for most geographic areas has us convert a vented crawl area from a cold damp problem source under a building to a dry, heated, conditioned space.

On 2018-01-18 by Jose

What is the correct height of a condensation drain line hanging over a floor drain? Is it 1" or 2"?

On 2017-09-12 by Sean

As you stated in the post above, running the condensate line into the crawl space is bad practice. But that is how the previous homeowners of my new home (or their plumber) had it. Unsurprisingly, we found some mold in the crawlspace and had to have it remediated

. What is the best solution to fixing the condensate drainage going to the crawlspace? The PVC pipe it is currently draining from is at least 15 feet from any outside wall and the crawlspace is only about 3 to 3.5 feet high. My fear with a pump in the crawl space would be freezing in the winter. Whats the best solution?

On 2017-09-06 by (mod) -

Joan

With the apology that no one can provide a for-certain answer to a serious building condition based simply on a brief e-text, and that an onsite expert will always find more, important information, it does not sound to me like the condensate drain installation you describe is proper nor that it would meet typical building codes.

Your local plumbing or building inspector is the final legal authority on that question, but in general we would not expect approval of simply dumping condensate into a crawl area: the risks include mold, legionnaire's disease, insect damage, rot, even structural damage.

On 2017-09-06 15:42:47.051141 by Joan

My Air Condition Core was replaced and they used rubber hose which I found out 2 years later was crimped and sliced because of a piece of metal it was pushed into. This has cause drainage on my wall and now my walls and flooring need to be replaced. They also pushed the drainage hose through flooring which drains into my crawspace eroding dirt under home and causing mold. Technician said they met requirements. Is this true?

On 2017-09-01 15:53:10.926932 by (mod) -

Sounds odd indeed, to drain other unit's condensate into your toilet, and a possible health hazard. Have you asked your doctor about this concern?

Also you may want help from your local building or plumbing code inspector

On 2017-08-30 22:48:47.558018 by Jenn

I recently found out that the 2 condos above me are draining their air conditioning condensation pipe into my water closet. The drain that the pipe is being drained into is really nasty looking, Red ish in color and white crystals are starting to form in the water. Please help My dog has started coughing over the past 2 years and I have asthma and keep getting really sick.

On 2017-07-19 01:56:09.279382 by (mod) -

No Eric that's a bad practice. I'd worry about
- bacterial hazards
- development of algae or mold on the surfaces leading to a slip and fall hazard

On 2017-07-18 19:12:48.562957 by Eric

Is it proper to place the discharg line from a.c. directly into a shower not the drainpipe of a shower just dripping into the shower

On 2017-07-18 18:34:23.417934 by Eric

I have a question regarding the condensate disposal line on the a.c.system in my rental property the line is ran directly into my showed where it is always a slimy discolored look at the front of my shower my landlord did the work on his own some time ago but i have been having some problems with my feet that i never had before is this an improper place to run the drain line thank you for any help you can give.

On 2017-07-07 14:18:08.269966 by Matt

Question.

We have a dirt crawl space that the installer of our furnace has just run the drain tube directly down to and is allowing it to drain through the ground below.

Is this proper?

On 2016-08-09 14:22:42.252070 by (mod) -

Yes Dan, you could add a condensate pump and pump the condensate out through a line that's high enough that where it discharges it won't get sand-covered.

On 2016-08-09 02:25:31.966272 by Dan

I bought a new house and the first floor is on a slap and the AC drain line drains outside.

My problem is the drain line is below the grade and I live in a sand area. When it rains, the drain line get covered up with sand. I have built a concrete block well around the drain line but I need to raise it up higher, the concrete blocks. Is there anything else that I can do?

On 2016-07-29 20:56:22.672590 by (mod) -

Dieter

IF the local plumbing codes where you live even permit the connection of the condensate drain to a sewer drain, THEN that sewer drain would normally be vented above the roof line. That's not an installation that I'd recommend.

On 2016-07-29 12:38:53.782365 by Dieter semder

Does a main stack A/C drain line in a multi story building have a vent to the roof ?

On 2016-07-07 23:05:01.035187 by (mod) -

What I don't understand is what mechanism is closing off the system - what is a vapor lock sensor? Can I buy one at Sears?

Your installer who eliminated a trap in the condensate drain system is asking for trouble: the purpose of the trap is specifically to avoid sucking harmful gases back into the air handler and blowing them onto occupants.

On 2016-07-07 18:37:05.553799 by Bruce Parker

First off I really appreciate your thoughts and response. I do have the system you describe in your first paragraph with the air handler located in the attic and the appropriate float switches. But, the system would shut down even though the drain line was not backed up.

This was the so called vapor lock and it was attributed to the trap in the drain line as it exited the house. But the system had worked fine with the builders grade Carrier system for 8 years since the house was built.

Your definition of my French drain captures the concept. The installer did it to eliminate the trap and give the condensate a clear path out of the house. But when the drain pine is under water (the French drain hole fills up) the system shuts down. The dealer says the shutdown relates to a difference in construction on the American Standard. I'm trying hard to get a factory rep involved in this but so far no success.

On 2016-07-07 16:13:48.136727 by (mod) -

Bruce I'm just baffled.

There are indeed systems that will shut down an A/C system when condensate is not draining properly, in particular, when an attic-located air handler drains condensate into a drip tray that in turn drains into a disposal drain system. If the drip tray accumulates water a small float switch shuts off the system to prevent a clogged condensate drain from overflowing into the attic floor.

But your drain system sound entirely different, and incompetent. A "French drain" - by which I am guessing you mean a perforated pipe buried in a gravel trench outside of a building - sounds rather an extreme method to dispose of A/C condensate. Why wouldn't an installer simply use a condensate drain pump that pumps the condensate to an acceptable destination such as a plumbing waste drain or to the outside of the building.

In all events the drain system someone installed is not working; the installer has to return to either fix that problem or use a working alternative approved by local building code officials for disposal of condensate.

"Vapor lock" is not a term I understand as having anything to do with condensate disposal.

On 2016-07-07 16:07:13.100262 by Bruce Parker

I have a big issue with my newly installed (01/16) American standard A/C system. I have a two stage condenser with a variable speed air handler. It replaced a Carrier system. We used the existing drain line with a trap draining to the outside of the house.

The system would shutdown and the installing company said it was vapor lock???. They removed the trap and created a French drain with the drain line below grade. The problem is hole fills with drain water that goes over the drain line and the system shuts down. I have to shop vac the water out of the hole daily to keep the system running. The dealer is of little help. Any suggestions?? bparker11@tampabay.rr.com

On 2016-06-20 10:36:17.797480 by (mod) -

Sounds as if the insulation is incomplete, with opernings permitting moist air in contact with cold refrigerant line;

On 2016-06-20 03:54:55.951531 by Becky

I have a condensate line (wrapped in foam) running to the havc unit in the ceiling above my bathtub. The insealation appeared to be damp and when I touched it water came pouring out. I gather this is not normal... any advice would be great.Thank you

On 2016-04-16 15:04:10.666472 by (mod) -

Karen:

All drain pipes connected to a sewer need to include a plumbing trap - otherwise dangerous sewer gases can enter the building.

A humidifier consumes water and evaporates it into the heating air of a furnace system.

A dehumidifier removes water from building air and needs to be drained.

If there are sewer gases entering the home the source needs to be found and fixed; it ought not cost thousands of dollars - something is wrong with this picture.

On 2016-04-16 12:28:28.081254 by Karen

Is it code to run the furnace humidifier drainage to a free standing pipe that goes to the ejector pump and sewer. A small pvc trap was created. Was told I need to add water to pvc 2 inch pipe above trap every so often. This does not seem right to me.

There is a floor drain a few feet away that goes to the ejector pump too. Seems like sewer gas is blowing through vent. I smell slight weird smell. What should I do? Worried about kids getting sick? What would be the proper way to do this? Spent $3100 so far. Please help. Just want this fixed

On 2015-06-17 20:31:12.485910 by (mod) -

I'd be surprised if the volume of HVAC condensate from a residential system could be enough ever to cause a structural dangerous sinkhole but if your particular site gives those concerns why not take a little more trouble to distribute the condensate over a wider area?

On 2015-06-17 02:26:18.900190 by JW

We have dual units in our house, both of which have a condensate drain outside that drips by the foundation (which has a small crawl space). There are 4 PVC pipes draining and the previous owner had them going into a 5 gallon bucket which filled nearly daily in the hot Lowcountry SC summers.

I used PVC connections and elbows to combine all 4 pipes into a single 1" pipe that I have buried underground for about 12 feet at a slight slope (maybe 3 inches over that length)

. It drains underground into my flower border, 6 feet or so from the front porch. Now that summer is upon us and 100 degree days and the units run nonstop, the ground over a 2 foot diameter is saturated where the pipe drains. Is this ok or will it cause any issues? I don't want to create a sinkhole or unforeseen issues! Thanks

...

Continue reading at CONDENSATE DRAIN CLEAN & DE-CLOG or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see this

HVAC Condensate Articles

• CONDENSATE HANDLING, HVAC - home
  • CONDENSATE LEAKS
  • CONDENSATE PUMPS
  • CONDENSATE DISPOSAL, IMPROPER
  • CONDENSATE DRAINS, CODES
  • CONDENSATE DRAIN CLEAN & DE-CLOG
  • CONDENSATE DRAIN INSULATION REQUIREMENTS
  • CONDENSATE DRAIN PROBLEMS
  • CONDENSATE DRIP TRAY DEFECTS
  • CONDENSATE PAN SWITCH LOCKOUT
  • Legionella BACTERIA & HVAC EQUIPMENT
  • CONDENSING BOILER/FURNACE CONDENSATE DRAIN
  • HARTFORD LOOP
  • Legionella BACTERIA & HVAC EQUIPMENT
  • SPLIT SYSTEM AC CONDENSATE LEAK REPAIR
• CONDENSING BOILER/FURNACE CONDENSATE DRAIN

Suggested citation for this web page

CONDENSATE DRAIN PROBLEM FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to AIR CONDITIONING & HEAT PUMPS

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