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AIR CONDITIONING & HEAT PUMP SYSTEMS
A/C - HEAT PUMP CONTROLS & SWITCHES
AIR CONDITIONER COMPONENT PARTS
AIR CONDITIONER TYPES, ENERGY SOURCES
AIR FILTER EFFICIENCY
AIR FILTERS, FIBERGLASS PARTICLES
AIR FLOW MEASUREMENT CFM
APPLIANCE DIAGNOSIS & REPAIR
APPLIANCE EFFICIENCY RATINGS
BLOWER DOORS & AIR INFILTRATION
BLOWER FAN CONTINUOUS OPERATION
BLOWER FAN OPERATION & TESTING
BOOKSTORE - Air Conditioning "How To" Books
CAPACITORS for HARD STARTING MOTORS
CLEANING & Legionella BACTERIA
CHINESE DRYWALL HAZARDS
CONDENSATION or SWEATING PIPES, TANKS
DEFINITION of HEATING & COOLING TERMS
DEW POINT CALCULATION for WALLS
DEW POINT TABLE - CONDENSATION POINT GUIDE
DIAGNOSTIC GUIDES A/C / HEAT PUMP
DIAGNOSE & FIX HEATING PROBLEMS-BOILER
DIAGNOSE & FIX HEATING PROBLEMS-FURNACE
DUCTS - Asbestos
DUCT INSULATION, Asbestos Paper
DUCT INSULATION for SOUNDPROOFING
DUCT SYSTEM & DUCT DEFECTS
DUCT SYSTEM NOISES
DUCTS, Asbestos Transite Pipe
DUST, HVAC CONTAMINATION STUDY
ELECTRIC MOTOR OVERLOAD RESET SWITCH
EVAPORATIVE COOLING SYSTEMS
FAN LIMIT SWITCH
GAS EXPOSURE EFFECTS, TOXIC
GAS DETECTION INSTRUMENTS
HEAT LOSS (or GAIN) in buildings
HEAT LOSS (or GAIN) INDICATORS
HEAT LOSS R U & K VALUE CALCULATION
HEATING SMALL LOADS
INSPECTION CHECKLIST - OUTDOOR UNIT
INSPECTION LIMITATIONS, A/C SYSTEMS
LEED GREEN BUILDING CERTIFICATION
LOST COOLING CAPACITY
LOW VOLTAGE TRANSFORMER TEST
MOTOR OVERLOAD RESET SWITCH
MOLD in AIR HANDLERS & DUCT WORK
OPERATING COST, AIR CONDITIONER
OPERATING DEFECTS, AIR CONDITIONING
REPAIR GUIDES A/C / HEAT PUMP
REPAIR & DIAGNOSTIC FAQs for A/C
THERMOSTATS, HEATING / COOLING
THERMOSTATIC EXPANSION VALVES
WATER COOLED AIR CONDITIONERS
WINDOW / WALL AIR CONDITIONERS
WINDOW / WALL A/C SUPPORTS
Air conditioner condensate handling & drainage defects: this air conditioning repair article discusses the inspection, diagnosis, and repair of air conditioning condensate drainage systems, including condensate leaks, condensate piping, traps, drains, condensate pumps, and the detection and hazards of air conditioning system condensate leaks in buildings. Condensate leak water health and safety concerns are also reviewed. This document describes the inspection of residential air conditioning systems (A/C systems) to inform home buyers, owners, and home inspectors of common cooling system defects.
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Improper handling of air conditioning system condensate is one of the most commonly reported set of A/C system defects. Condensate problems can lead to leaks into the building, costly mold or insect damage, or even to complete A/C or heat pump system shutdown.
Perhaps we see lots of air conditioning condensate leaks and related problems in part because these defects are easily observed visually, and perhaps also because some A/C installers do not follow basic plumbing and building code requirements for handling the discharge of the condensate produced when an air conditioning system is operating.
Sketch courtesy of Carson Dunlop Associates.
Condensate leaks or discharge errors (such as the drips into the dog bowl and cooking pot in this attic) present several risks of ugly surprises in buildings.
Here are some inspection tips that can avoid a condensate leak or even a costly mold problem in the air conditioning system air handler, duct work, or in the building itself:
Locate how & where condensate discharge is carried for final disposal
Check for a clogged A/C condensate drain line trap
One of the most common causes of air conditioning or heat pump condensate leakage and overflow is a clogged condensate drain line trap. And if the secondary or emergency condensate handling system is absent or defective, the result can be costly leak damage to the equipment or to the building.
Carson Dunlop Associates' sketch (left) illustrates the requirement for a trap on the A/C condensate primary drain line.
Look out for a missing condensate overflow pan or drip tray:
If there is no overflow pan under the air handler, especially in units installed on upper building floors or in an attic, when the condensate drain clogs or the condensate pump fails you can expect to have leaks into the building and possibly costly mold or water damage.
See DRIP TRAY DEFECTS for details.
Look out for an improper condensate overflow pan drain connection
A condensate pan should have its own independent drain to an approved location. Otherwise, for example if it shares the main condensate drain pipe, you have not gained much protection. An alternative to a drain on a condensate overflow pan is the installation of a Float Switch on Condensate Tray that will turn off the system if water is detected. See CONDENSATE DRAINS.
Look for corrosion or water stains on floor surfaces around the equipment
Check the condensate drip pan and at bottom of the "A frame" cooling coil, indicating that the drain may need cleaning and more important, indicating that the condensate is leaking out of the equipment or drains and not being carried to an acceptable disposal point.
Links below continue with detailed discussions of condensate handling components, defects, cleaning, maintenance, and repairs.
Question: how and when do we inspect the condensate drain?
I can't find a description of the method for inspecting the drain pipe leading out from the drain pan under the condenser coils.
I have been told that this pipe commonly blocks up and causes problems and that inspecting it is a part of a HVAC maintenance program. Would you describe for me, or maybe add to your site, how often and how this drain line should be inspected and maintained?
- R.B. Chattanooga, TN.,
Reply: check for a clogged condensate drain line trap, crimps in the line, or clogs in the line; check that the line is routed to a proper destination
The condensate drain line, trap, and evidence of blockage, leaks, overflow, or improper piping should be part of annual air conditioning system service, or should be performed immediately if there is evidence of a condensate spill or leak. It only takes a quick look by an experienced service technician to see trouble. Here are some signs of trouble that a visual inspection of the condensate drain system might pick at an inspection:
Check out the articles listed below for more detail about each type of condensate drain system defect.
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Frequently Asked Questions (FAQs)
Question: Our heat pump spills water onto the floor. What's wrong and how do we fix it?
I have a question regarding our heat pump. Last summer it started leaking water. The system otherwise runs fine but we have to keep a bucket where the water comes out a rubber tube. This also does not catch all the water because the carpet still gets wet. There is no problem with heating this past winter. Is there a pump of some kind that needs to be replaced.- M.M.
It sure sounds as if your heat pump when in cooling mode is leaking condensate into the building. When warm moist indoor air passes through the cooling coil, moisture is removed from the air as it cools, condensing into water that must be drained away to an acceptable location - a floor drain or in some areas outdoors onto the ground.
A condensate leak that spills into the building interior could be caused by any of several problems such as a clogged condensate drain line or if a condensate pump is used to lift condensate from a receiving container up to a building drain, the pump could be switched off or broken.
You need to first diagnose the cause of the problem. If it's just a clogged drain line, clearing the line can get things working again quickly and probably at little or no cost. If you are unfamiliar with the equipment or can't find the condensate handling system, or if a condensate pump is not working you probably need a service call by an HVAC expert.
Watch out: in a good heat pump/air conditioner installation, the installers make provision to protect the building interior from condensate leakage should the primary condensate drainage system fail. Usually that's in the form of a condensate drip tray that is placed under the indoor air handler where the cooling coil is located (and where condensate is produced). If the condensate drain system fails and condensate begins to leak out of the equipment, the drip tray either takes condensate safely away to a drain by a separate drain line or it uses a switch that shuts down the equipment so that you know repairs are needed. Condensate that leaks into building carpets, ceilings, walls, risks formation of a costly mold contamination issue. So get this matter repaired promptly.
Question: Water blowing down my HVAC Supply Ducts, What Can I Do to Stop It?
Why is water blowing down my supply duct system? I have solved the freezing up problem, I don't have a drain problem!! I added refrigerant to solve the freezing up problem, but it is still blowing water down my supply line. How do I stop this?? - C.T.
Reply: Check the A/C system sizing, check for abnormal indoor humidity sources
If you are sure that the condensate drain is in fact draining, I don't know a simple in-air-handler fix for this problem - it's common in some humid areas such as Florida. I'd take a look at these next steps:
Question: our wall-mounted split system air conditioner leaks condensate down the interior wall
We noticed water stains and wet spots on the wall below our wall-mounted split system air conditioner. But condensate is also coming out of the drain line on the roof. What might be wrong? - Ed.
Reply: Common defects that cause leaks or blockages in wall-mounted air conditioner condensate drains
If the wall mounted air conditioner is not level, condensate may collect in its internal drain pan but may overflow the (relatively shallow) condensate pan edges before reaching the condensate drain opening. Check the unit for level, and watch out: the plastic cover may not be dead straight - it's the unit itself that should be level for the condensate drain pan to work properly. The photo at left is explained at SPLIT SYSTEM AIR CONDITIONERS & HEAT PUMPS. That white line is the condensate drain headed from the wall-mounted unit (not shown) to outdoors.
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