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air conditioning water damageAir Conditioner Condensate Problems - It is important for air conditioning preventive maintenance to be performed on your system to avoid problems. Condensation water leaking near the air handling unit can be avoided with proper air conditioning repair and preventive maintenance. Normally this is a very simple problem that can be fixed in less than 30 minutes. Here is a list of what can cause water around the outside of the air conditioning air handler unit.

Air Conditioner Condensate Problems - Possible Causes

  • The black insulation (called Rubatex) has a tear in it or doesn’t cover the entire suction line. This line normally (in Air Conditioning air condition mode) operates below the dew point and will sweat if it is not insulated. It must have a sealed vapor barrier to be effective.

Condensation Drain Plugged

  • The insulation surrounding the air handler supply transition or ductwork is torn. The supply transition and duct can operate (under the right conditions) below the dew point and sweat. It is important that the transition have a vapor barrier around it. This scenario is especially true for those that have over sized units.

Air Conditioner Condensate Problems – Condensation Drain Plugged

New Air Handler with Secondary Condensation Pan Under Unit and Showing the Float Switch

  • The condensation drain line is plugged. Air handling units in attics should have a secondary condensation pan in case the primary condensation pan overflows. Occasionally, the secondary condensation pan will also clog and not drain. Water builds up in the ceiling and eventually there will be a drip if the homeowner is lucky. If no drip, then eventually the entire ceiling will fall. In the attic, I always recommend a float switch installed in the secondary air conditioning condensation drain pan. If the secondary condensation pan fills, the float switch will rise and cut the whole air conditioning unit off. This will force the homeowner to look for a problem or call an HVAC technician. In this case, with the float switch, the problem can be rectified before water damage occurs. Algae or a foreign obstruction such as mulch or potting soil can plug condensation drain lines. These air conditioning condensation drain lines (either black plastic or white plastic looking pipes) usually drain out somewhere at the base of the house into a flower garden. Make sure mulch or soil doesn’t plug these condensation lines up. Adding algae treatment to the lines or pans can prevent algae. Some people pour bleach in the evaporator condensation pans once a year. Whatever the way you use to prevent it from growing in your evaporator condensation pan, know that if steps aren’t taken to prevent algae growth, it will eventually plug the condensation lines.
  • If the air filter is extremely clogged, a duct is collapsed, the evaporator coils are plugged with dirt or dust because no air filter was kept in the system, or there is a low charge of Freon, the evaporator coil will freeze. When it thaws, it will overwhelm the evaporator condensation pan and leak outside the air handling unit.
  • Rust. Some evaporator condensation pans are made of metal and can rust through over the years of use. In certain cases, the entire air handling unit must be changed out. In other cases, the evaporator coils and evaporator condensation pan must be changed. Normally if the air handler unit is old enough to have a rusted evaporator condensation pan that leaks, it is time to change the air handling unit.
  • Unit or Drain Pan Slope. If the evaporator drain pan is not sloped toward the drain the water will not drain from the evaporator pan properly. Additionally, the condensation drain piping must be sloped.

Related Link: See what a clogged drain for an air conditioner can do to cause water damage to your home. (opens in a new window)

Insulation Problem | Air Conditioner Condensate Problems

In either case the condensation drain or any other thing that can cause a condensation leak should be repaired as it will cause water damage to wood and mold and mildew issues that can affect health. Moisture dripping into insulation also derates the insulation R-value so the insulation is not as effective.

Air Conditioner Condensate Problems - Conclusion

If your condensation drain got clogged or plugged or something caused the drain pan to overflow and the insulation got wet including the insulation on the duct work this insulation needs to be replaced. The insulation for the house in the attic or other place will not insulate as it did before it got wet. Additionally, the insulation surrounding the duct work needs to have air tight integrity and a good moisture barrier. If it does not have a moisture barrier and humid moist air penetrates the insulation to the duct work then the duct work will begin to sweat.

The excess moisture will eventually drip into the insulation surrounding the duct work and before long it begins to sag and this separates the insulation at the seams and causes more moist air to reach the duct work creating a larger moisture issue. Eventually, the insulation will fall off the duct work and all the water will cause water damage. Seal that duct work insulation to prevent this from happening.

Nu-Calgon 4296-60 Pan-Treat Scum 200 Tablets to prevent drain clogs for condensate pans available here

High Performance HVAC

Air Conditioner Condensate Problems – Condensation Drain Plugged


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