Air Conditioning / Heat Pump Condensate Drip Trays, Defects, Repairs
     

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Question: My condensate drain seems clean but the overflow tray still is leaking

My AC unit inside unit overflows into the crawling space. I have cleaned the drain pipe and the air handler coil but the unit still overflows out of the coil tray. What could be the cause(s) of this? - Angel J 6/16/11

Cleaned out the condensate drain pipe with shop vac, bleach, and weak mattress blower.

Only observed draining from the primary pipe during the day (85 - 100 degrees F) but noticed a little dripping from the overflow pipe at night (not continuous). Guessing up to a cup of water from overflow.

Primary condensate pipe still clogged? What kind of plastic tube would work as snake? - Mark 6/27/11

Reply:

Angel: Carson Dunlop Associates' sketch (above left) illustrates what happens when a condensate tray leaks, risking costly damage to the equipment. Your question is why the condensate keeps flowing out of the tray when you are confident that the drain is not blocked.

When the air handler condensate system is leaking into the crawl space and you are sure that the condensate drain pipe is unclogged and properly pitched, I have to guess that there is a problem with the condensate collection pan inside the air handler such as:

- the drain in the pan itself is clogged with debris - you'll need to turn off and look inside the air handler

- the drain pan is corroded through and leaks - it will need patching or replacement;

- the drain pan or the whole air handler is not properly leveled - it may be sloped away from the condensate pan drain opening so that condensate collects in and runs over the edge of the pan in another direction.

Let us know what you find - it'll help other readers.

Mark:

There is an almost overwhelming number of products and methods sold for cleaning out A/C condensate lines, drains, and traps, and various tricks of the trade that fit to individual installations and situations. I've used a small flexible bottle brush to clean A/C condensate traps; if the blockage is further along the line I've successfully used a small diameter flexible plastic tube bought at the local hardware store. - DF

Question: A/C condensate leaks into ceiling or into the attic

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? - Frank 7/22/11

My a/c unit on my roof is leaking into the attic and causing water spots inside the house (ceiling, walls). After having a friend check it out, we think the plastic drip tray, which the condenser is resting in, has a crack or hole causing the leak. The question: How do we get to the drip tray to repair or replace without removing the condenser? - J. 8/1/11

I rent my home and have for 5 years. I noticed a water spot in my bathroom ceiling and went upstairs to check the air conditioner being that it is right above the bathroom. The tray was FILLED. I laid towels down to soak up the water. Today is Saturday. Can I wait to call my landlord on Monday as long as I continue to soak up the water? Also, what could the problem be. It DOES have that switch mentioned above but it must not be working... - Kelli 6/23/12

Reply:

Frank,

at higher fan speed sometimes the blower pushes water droplets into the ductwork instead of allowing all of the condensate in the air handler to run into the drip tray. But when you find an obvious leak like a hole in the drip tray, that's a good diagnosis for leaks into the ceiling. If your drip tray is metal it may just have corroded; plastic - it was damaged. Usually there is a primary condensate collection drip pan connected to a drain location, and a separate condensate overflow pan and drain to handle the sort of problem you describe.

J,

replacing the drip tray under a rooftop A/C unit is easy or difficult depending on how it was installed. If the installer left sufficient slack (a flexible loop) in the refrigerant piping and electrical wiring, the system can be raised very carefully, disturbing the piping as little as possible to avoid causing a leak in the refrigerant lines. Then the new tray is placed beneath.

But if there is insufficient slack in refrigerant tubing and wiring, moving the system to install a new drip tray is a big deal because you'd have to evacuate the system, cut refrigerant lines, then install the tray, then repair the lines and clear and recharge the whole system.

That procedure is so much trouble and cost that most folks will try to find and repair leaks in the existing drip tray first.

Kelli,

I suspect that the condensate drain is clogged - usually a little brush can clear a trap in that line - but yes, if you keep water from overflowing into the attic by any means you can keep running the system. But it sounds troublesome. I'd focus on getting someone to clear the drain.

Reader follow-up:

Thanks Dan. We will see if the condenser has any slack to lift it off of the tray. Any other ideas?? I also saw someone mention something about some of the moisture from the condenser being sucked into the air intake then resting in the ventilation somewhere, pooling, then leaking. Since the air intake is a big hole just under the condenser, I consider this a possibility. Any ideas on this one? - J

Reply:

Sometimes in the air handler the blower pushes moisture off of the cooling coil and off into the ductwork - common in very humid spots like Florida.

Question: A/C condensate pan emergency overflow float switch

Can someone tell me what an emergency float switch typically cost? I have one attached to my drip pan on an Amana. - Molly 8/11/11

Reply:

Molly

if you need an air conditioner condensate pan or drip tray float switch installed, the cost will principally be the fee for an HVAC service call to install the switch in the pan (trivial) and wire it to the A/C controls (less than an hour). Figure $100. to $150.

The switch itself, such as the Safe-T-Switch Model SS3 sold as a drip pan overflow shut-off switch, retails from $30.00 to $50.00 U.S.

Question: A/C condensate blows into the duct work

An earlier comment mentioned air pushed into the duct by the blower. I have had condensate leaking from the bottom duct of my downflow system for several years on to the garage floor. Has not been a big issue because I live in Oregon and only use AC a few days a summer and humidity is very low. I have determined that the condensate is blowing or splashing out of the tray in the center of the evaporate. The drain is OK. What can be done about this? I will be selling the house next year and I,m sure it will be an issue. - Dan 8/20/11

Reply:

Dan,

While some of my associates (M. Cramer, Tampa) point out that a small amount of condensate blow-off at the cooling coil and even small amounts of mold in that area (usually Cladosporium sp. in my tests) are not necessarily a functional issue, I'm still looking for a "fix" for condensate blowing out of the drip tray; I agree that it's common, especially in very humid areas. My associate Mark Cramer, a Florida home inspector and educator, says they just live with it and they don't believe mold is much of an issue in ductwork; I think .... also paraphrasing Mark... it depends. Small amounts of immobile Cladosporium sphaerospermum sticking to insulation may have no detectable effect in the living area; Aspergillus or Penicillium in the same area would be more of a worry. This is a good question to take to the manufacturers to ask what design changes in air handler airflow control may be in the works. - DF

Question: Condensate Drip Tray Replacement

can the drip pan be replaced with out replacing the condenser itself - Peter 5/6/12

Reply:

Peter:
Yes, well sort-of. It can be difficult on many air handlers to get a new drip pan in place inside of an air handler without doing some disassembly. But drip pans and their replacement take place inside the indoor unit, the air handler or blower unit - and have nothing to do with the outdoor condenser unit.

Question: Condensate Drip Tray Not Level

Our condensation drip pan is not level, so the condensate water is flowing away from the drain hose and overflowing into our furnace instead of down the drain. I was told the pitch of the pan needs to be adjusted- what is the best and safest way to adjust the pitch? Our AC unit is on top of our furnace. - Tony 6/22/12

Reply:

Tony, to properly adjust the slope of the condensate drip pan you need to know how it is secured and what movement is possible; I don't have enough information to figure it out from just your comment; you could try sending some sharp photos to the CONTACT US link. If the pan is "pinned" under the A/C unit itself, you may not be able to level the pan without moving the whole assembly. If the pan moves freely it may just be shimmed. But if this is a new problem, that is if it used to drain, I'd look for what changed and ask why - that'd be diagnostic.

Question: Condensate dripping out of the air handler

My indoor ac unit is dripping water from somewhere in the upper part of the system. I checked what I believe is the condensate drain and it doesn't appear blocked. Interestingly, this drain goes into the floor (concrete basement floor) into a hole. I can't see into the hole since it's under a corner of the unit. I cut the PVC drain pipe so I could get my wet vac to it. I didn't get an appreciable amount of junk from the pipe and will replace it shortly. Also, the lines from the outside unit are freezing a bit and I see condensation along the lines that lead to the inside unit. Any information would be appreciated. - Duane 7/8/12

Recently, I have noticed water dripping down the outside of my furnace. The A coil is above the furnace, drain is located on the side of the drip pan, and the coil and integrated pan are "lift able" (not attached to the furnace) so it can be shimmed which I tried. I cleared the drain, but it was not clogged. The drip pan is showing a large amount of rust and I suspect pinholes in it, so the water is dripping through it rather than going to the drain. I have researched and found a product called Pancrete which appears to be made for just this problem. Has anyone here used this product and would they recommend it? System is Ruud upflow furnace approximately 18 years old. - Jeff F. 7/21/12

Reply:

Duane:

A first step in diagnosing condensate dripping out of the air handler is to determine if the entry into the condensate drain or any later portion of the drain is clogged - if water can't get from the pan into and down the drain the pan is going to overflow.

Also on occasion I find misaligned A/C components, a pan that is not in the right place, a pan that has corroded and is leaky, or missing insulation on a refrigerant line that is causing condensate to drip somewhere other than into the drip tray.

Jeff

I haven't looked at PanCrete but will see if I can find and review the product literature; it's worth a try if it can seal a corroded condensate pan instead of having to tear the system apart to get a new one in place.

Condensate drip tray replacement under an A coil in a cooling system such as the one you describe can be tight.

Question: Blower unit won't come on - the condensate drip tray is filled up - is there a float switch?

my outside unit is working but my blower in the attic is not, After checking my one 10amp fuse I noticed that not only was my drip pans filled but so wa the bottom insulation of my system, I have to separate drain pipe...do I still have a float switch and what should I do next? - Anon 7/16/12

Reply:

Anon:

Float switches are used in condensate OVERFLOW pans as a safety measure to shut down the system when condensate is not draining properly - to avoid a flood out of the pan and into the house ceilings. But if your overflow pan has its own drain it usually won't have an overflow switch. In other words usually there is either an overflow pan with a drain, or an overflow pan with a water-sensing switch that shuts down the system if ANY water appears in the overflow pan.

Because you say your overflow pan has a separate drain pipe, I suspect it won't have a switch.

If you had an overflow switch you would see it and its wires somewhere in the bottom of the overflow pan.

So you need to look for a different problem: lost power, a blower compartment door open (those have a safety switch that shuts off power if someone opens the door - to avoid getting chopped by the blower fan), or a bad control, relay, etc.

Question: How Much Condensate Flow Should I be Seeing From My Air Conditioner - what's normal?

I have noticed quite alot of water draining from my drain hose which comes from the unit located in the attic. The drain hose comes from the attic unit, then outside and down the side of my home. I placed a bucket under the drain pipe due to the amount of water pooling around the foundation of the home. I can usually fill up this 5 gallon bucket within a day or two with the water draining. Is this normal? - Patrick S 7/30/12

Reply:

Patrick,

Normal A/C or heat pump condensate flow ranges from nothing to considerable, even quarts per hour in some residential installations and of course still more in larger commercial systems. A system that is operating in a dry environment or that has been on for some time may be encountering little moisture to remove from the conditioned air, while an air conditioner running in very humid conditions may pull an enormous amount of water from the air.

In humid conditions an A/C system can produce a lot of condensate - it's not abnormal unless there is also an abnormal source of moisture in the building. Also when a cooling system is first activated after some period of disuse, as it removes moisture from the building air, more moisture from absorbent building materials (drywall, for example) continues to enter the building air until the moisture level in both air and building contents has been reduced to a stable level.

And of course there is no simple "correct" condensate quantity because in addition to these environmental variables, the cubic feet and type of area being air conditioned varies from building to building as does the dehumidification capacity of the equipment.

As long as

• there are no improper in-building moisture sources
• there are no odd leaks into the ductwork from some plumbing or other source
• the condensate is successfully draining out of the system to an acceptable destination

you're probably ok.

Watch out: about too little condensate production from an air conditioner or heat pump: we explain in detail at DEHUMIDIFICATION PROBLEMS that if an air conditioner is over-sized it will cool the space off too rapidly and it won't dehumidify adequately.

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• [1] Safe-T-Switch Model SS3, Rectorseal, 2601 Spenwick Dr., Houston TX 77055, Tel: 713-263-8001 or 800-231-3345, web search 8/11/11, original source: rectorseal.com Thanks to Mike Giaquinto and Scott at SJM Inspect for technical editing remarks, 5/16/07
• [2] Thanks to Lester Richer, a professional home inspector, for the reminder that a bad air conditioner condensate drip tray switch can shut the whole system down.
• [3] Modern Refrigeration and Air Conditioning, A. D. Althouse, C.H. Turnquist, A. Bracciano, Goodheart-Willcox Co., 1982
• [4] Principles of Refrigeration, R. Warren Marsh, C. Thomas Olivo, Delmar Publishers, 1979
• [5] "Air Conditioning & Refrigeration I & II", BOCES Education, Warren Hilliard (instructor), Poughkeepsie, New York, May - July 1982, [classroom notes from air conditioning and refrigeration maintenance and repair course attended by the website author]
• [6] Refrigeration and Air Conditioning Technology, 5th Ed., William C. Whitman, William M. Johnson, John Tomczyk, Cengage Learning, 2005, ISBN 1401837654, 9781401837655 1324 pages
• [7] Carson Dunlop, Associates, Toronto, have provided us with (and we recommend) Carson Dunlop Weldon & Associates' Technical Reference Guide to manufacturer's model and serial number information for heating and cooling equipment ($69.00 U.S.).
• [8] Asbestos HVAC Ducts and Flues field identification photos and guide
• [9] Fiberglass: Indoor Air Quality Investigations: Fiberglass in Indoor Air, HVAC ducts, and Building Insulation
• [10] Fred Nickols, "Solution engineering: choosing the right problem solving approach", Veracruz University, 2000, Web search 7/30/12, original source: http://cdigital.uv.mx/handle/123456789/5997 - Quoting: "Then he asked himself, “What should be happening here?” He was not an expert on air conditioning systems, but he knew enough to realize that condensate from the evaporator was sup- posed to run down into the drip tray, out the ..."
• [11] AP Sawant, N. Agrawal, "Performance assessment of an evaporative cooling-assisted window air conditioner", nt. J. Low-Carbon Tech. (2011) doi: 10.1093/ijlct/ctr029 First published online: November 23, 2011 Abstract:
  Substantial growth in refrigeration and air-conditioning industry has made a significant impact on net energy consumption. Condenser pressure is one of the critical parameters in the energy-efficient operation of refrigeration and air-conditioning systems. A novel system is developed to use the condensate, available at the cooling coil, for condenser cooling of a window air-conditioner unit by employing evaporative cooling. Performance testing of the system has shown 13% savings in energy and up to 18% enhancement in coefficient of performance. The maximum benefit of the evaporative cooling cycle over the basic cycle was found to be in the region of moderate climatic conditions.
• [12] Yunho Hwang, Reinhard Radermacher, William Kopko, "An experimental evaluation of a residential-sized evaporatively cooled condenser Evaluation expérimentale d'un condenseur à refroidissement évaporatif en application résidentielle", International Journal of Refrigeration Volume 24, Issue 3, May 2001, Pages 238–249, Abstract:
  In this paper, the performance of an innovative evaporatively cooled condenser is compared with that of a conventional air-cooled condenser for a split heat pump system. The system was tested in an environmentally controlled test chamber that was able to simulate test conditions as specified by ASHRAE Standard 116. Tests to optimize refrigerant charge and short tube restrictor size were conducted using refrigerant HCFC-22. The wheel rotation speed of the evaporative condenser was also optimized experimentally to maximize the coefficient of performance. Using these optimum parameters, steady state and cyclic performance tests were conducted. The experimental results showed that the evaporative condenser has a higher capacity than the air-cooled condenser by 1.8 to 8.1%, a higher COP by 11.1 to 21.6%, and a higher SEER by 14.5%.
  Résumé Dans cette communication, on examine la performance d'un nouveau condenseur refroidi par évaporation ; on compare sa performance à celle d'un condenseur refroidi par air classique utilisé dans un système split de pompe à chaleur. On a testé ce système dans une chambre à environnement contrôlé afin d'obtenir des conditions d'essai requises par la norme ASHRAE 116. On a réalisé des essais destinés à optimiser la charge en frigorigène et les détendeurs pour HCFC22. On a optimisé de façon expérimentale la vitesse du moteur de rotation du condenseur évaporatif afin d'augmenter le coefficient de performance le plus possible. A partir de ces paramètres optimaux, on a effectué des essais en régime permanent et sur la performance du cycle. Les résultats expérimentaux montrent que le condenseur évaporatif a une puissance supérieure à celle du condenseur refroidi par air (de 1,8 à 8,1 %), un COP de 11,1 à 21,6 % supérieur, et un SEER* de 14,5 % supérieur.* SEER (Seasonal Energy Efficiency Ratio) = Rapport d'efficacité énergétique saisonnier
• Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides:
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• Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.

• Carson Dunlop, Associates, Toronto, have provided us with (and we recommend) Carson Dunlop Weldon & Associates' Technical Reference Guide to manufacturer's model and serial number information for heating and cooling equipment
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