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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.
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.
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
Continue reading at CONDENSATE PUMPS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
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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
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
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
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Questions & answers or comments about the hazards associated with air conditioner or heat pump condensate drip tray or overflow tray leaks
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Thanks to AMike Giaquinto and Scott at SJM Inspect for technical editing remarks
Thanks to reader Jacob Behrends, FL for discussing how a clogged condensate drain line can overflow condensate into a condensate pan that in turn may contain a safety switch that shuts down the whole air conditioning system. August 2010.
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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Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
"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]
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: firstname.lastname@example.org. 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 extensive home inspection education and report writing material.
The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors. Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
TECHNICAL REFERENCE GUIDE to manufacturer's model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop, Associates, Toronto - Carson Dunlop Weldon & Associates Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
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