This air conditioning repair article discusses the problems and hazards caused by leaky air conditioner or heat pump condensate drip trays and overflow pans.

We address the inspection of air conditioning condensate systems, including air conditioning condensate leaks, health hazards from air conditioner leaks, the related mold risk, and condensate leak repairs, as well as condensate piping, traps, drains, condensate pumps, and the detection and hazards of air conditioning system condensate leaks in buildings.

Air conditioner or heat pump condensate leak health and safety concerns are reviewed here.

Air Conditioning System / Heat Pump Condensate Leaks

See our complete list of air conditioning and heat pump condensate handling system inspection, diagnosis, and repair articles beginning
at CONDENSATE HANDLING, HVAC.

When a cooling coil is installed atop a hot air furnace, air conditioning condensate leaks may drip onto the furnace heat exchanger.

Safety Warning about flue gas leaks: leaks onto a furnace heat exchanger can cause rust damage and holes, risking dangerous carbon monoxide leaks and requiring replacement of the heating system.

Further investigation of the source of leakage and the condition of the furnace heat exchanger is needed promptly - this is a safety concern.

 

Condensate Line maintenance tip: If the condensate line becomes plugged system condensate overflow will spill onto and rust and possibly seriously damage the furnace heat exchanger. During system operation you should periodically confirm that condensate is being discharged properly.

This sequence of photos shows of an attic air conditioning condensate line what happens when an amateur rigs up a condensate drain in an attic without proper glue, support, and slope.

The plastic piping was not securely supported and when touched, fell apart to spill condensate into the attic floor and into the ceilings below.

Condensate leaks into an attic ceiling risk not only damage to the building but a hidden mold reservoir in the building insulation or on the attic side of the ceiling drywall below.

Since this air conditioning attic system was the same one which showed the dog bowl and kitchen pot in use to catch condensate drips at the air handler unit, the inspector was not remiss in checking the remainder of the condensate drain line rather aggressively.

Condensate leaks from the air handler's internal drip tray (below the evaporator coil) occur if the internal drain is clogged.

When condensate wets the insulation on the interior of the blower compartment there is risk of problematic mold growth in the system.

In warm humid climates such as the Southern U.S., high levels of condensate production in the air handler unit can also result in movement of condensate downstream into the supply duct, forced there by the blower itself.


Missing air conditioning condensate trap:

[Example air conditioning inspection report language]: We did not see a trap on the condensate line itself - usually installed as good practice - ask your HVAC service person about this detail. It could be required for sanitary or other reasons. CONDENSATE TRAPS have several function including avoiding possible draw of unsanitary air or bacteria back into the building air supply.

Readers who need to clean or unclog a blocked or leaky overflowing A/C or heat pump condensate drain should

see CONDENSATE DRAIN CLEAN & DE-CLOG.

Condensate Pump Leaks & Drain Clog Can Turn off the Air Conditioner

In Florida we have air conditioner drain pumps that pump out the water from condensation.

In tracking down an air conditioner condensate leak, I found that the the condensate pump drain line, a small-diameter PVC pipe, was clogged with water mold.

That was why my air conditioner wasn't kicking on.

It would of ended up costing at least a hundred dollars just for a service tech to fix something as simple as that. I had to take the pump apart and clean it. I took off the PVC drain line coming out of inside air conditioner and blow and clean it all out too. - Jacob Behrends, FL

We suspect that due to the clogged condensate drain line on Mr. Behrends' cooling system, A/C condensate was overflowing into a condensate overflow pan that used a sensor switch that responds to water in the overflow pan by turning off the A/C system.

This design is intended to prevent condensate from overflowing the pan and flooding the building - a possible source of mold or other damage - DF

...

---

---

ADVERTISEMENT

---

---

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2020-09-13 - by (mod) -

heating system water line vented into the ductwork causing mold

Fix the leak
Remove the mold

If the ductwork is not able to be cleaned (such as fiberglass ducts or flex-duct) it most-likely needs to be replaced.

Clean the air handler.

Check the building for excessive mold or moldy dust throughout.

On 2020-09-13 by Anonymous

My heating system water line is directly vented into the ductwork for 22 years causing severe amounts of black mold. What needs to be done to make it a livable situation to stay based on the impact on the occupants

On 2018-04-04 - by (mod) -

It seems unlikely that the odor from your son's paint job of show up more in other rooms than it does in his own.

On 2018-04-04 by Jackie

I have a question. Moved in house that's on a concrete slab about 8 months ago. My son painted his room only, and the paint smell was gone soon. But now when weather is humid or it rains i get paint odor in certain rooms of the house. Not his room though his room does not smell like this paint/solvent odor. Could it be an hvac issue the unit is about 16 years old. The roof is also due for replacement might it be a leak we can't detect making ceiling off gas old previous paint work in other parts of the house? I'm wondering if his painting sealed off odors in his room?

On 2017-05-29 18:58:16.303187 - by (mod) -

Diane;

I want to help too but can't see enough from here in our ivory tower. In basic terms if the condensate drain doesn't drain - but instead backs up or leaks - it is either blocked somewhere along its route or it slopes uphill so doesn't drain by gravity. A temp fix would be to add a condensate pump and send the condensate to another drain that IS working, but I'd think the drain could be de-clogged using a small plumbing snake or perhaps even a pneumatic drain cleaner.

Sonya's observation of an apparent non-functioning condensate drain line, written in December, might have been because the humidity level was low enough that very little condensate was being produced when she looked at the drain.

On 2017-05-29 by Diane

My AC drip drains when I pour water down. Water comes out using suction vac but doesn't drain when AC unit is running. Can anyone explain why. Numerous AC guys can't fix.

On 2016-12-19 by Sonya

Why is there no water coming out of my drain line from attic?it has always drained properly, and checked in attic and there is no visible water anywhere.

On 2016-07-25 - by (mod) -

I can't tell from an e-text what you might be breathing, Anon, but if there are odors AND if they're coming from the A/C system I'd shut it off, call for a professional inspection and if needed, cleaning and repair;

In some cases such as when the condensate drain does not include a plumbing trap and when some fool has connected the drain line to a sewer pipe, negative pressures in the air handler can suck sewer gases back up the condensate drain and blow them into the occupied space.

Odors can also enter the ductwork from other sources including near the return air inlet or even from a dead animal in the ductwork.

On 2016-07-24 by Anonymous

if condensation line is leaking can i run air conditioner...it smells ike urine..what am I breathing in?

Question: water comes out of my system when I turn on the A/C

When i turn on the (AC Outside unit Lennox ) there is an overflow of water in my basement at the furnace which is a gas furnace- Don 7/24/11

Reply:

Don if you see water in your basement at the A/C unit when it's on, your condensate drain or pump is not working.

Question: No water is coming out of the condensate drain

water is not going through the drain hose - Anon 7/20/12

Reply:

Anon:

If you don't see condensate coming out of the condensate drain there are several likely explanations:

- the drain system for condensate has become clogged - you need to clear the drain line - check this first

- the system is off or not in cooling mode so not producing condensate

- the air is dry enough in your environment that not much condensate is being produced

- your system uses a condensate pump that has lost power or failed

...

Continue reading at CONDENSATE PUMPS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• CONDENSATE HANDLING, HVAC
  • 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
• DUCT SYSTEM DESIGN SIZE & DEFECTS - home
• SLAB DUCTWORK
• WATER & ICE IN DUCT WORK
• WET CORRODED DUCT WORK

Suggested citation for this web page

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

Or see this

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

Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia

Ask a Question or Search InspectApedia

Try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Note: appearance of your Comment below may be delayed: if your comment contains an image, photograph, web link, or text that looks to the software as if it might be a web link, your posting will appear after it has been approved by a moderator. Apologies for the delay.

Only one image can be added per comment but you can post as many comments, and therefore images, as you like.
You will not receive a notification when a response to your question has been posted.
Please bookmark this page to make it easy for you to check back for our response.
Our Comment Box is provided by Countable Web Productions countable.ca

Citations & References

In addition to any citations in the article above, a full list is available on request.

---

ADVERTISEMENT

---