Water Dripping from Air Conditioner - We have 2 air conditioning units in our house and 2 pipes protrude from the roof. One of the pipes is dripping water. We were told to look for a blockage and to empty the pans. I don’t see where to check for a blockage. Any suggestions?
The air conditioning units we have: Bryant models 373LAV, 376CAV Downflow/Horizontal and 383KAV, 395CAV Upflow Gas Furnace.

Water Dripping from Air Conditioner | Condensation Pipe Drain Answer

Water Dripping from Air Conditioner

Water Dripping from Air Conditioner

Thanks for visiting High Performance HVAC and asking a good question. I see you have two zones so actually, you should have more than two drains. Possibly 3 or 4 drains depending on where the units are located. Typically air handling units installed in the attic or closet spaces upstairs will have two condensation drain pipes for condensation. There are some systems that utilize a pump rather than a drain.

One is the primary condensation drain pipe where the water should continuously drain the condensation during the cooling season and in the winter heating season if you have a high efficiency condensing furnace. In the summer it is possible these drains could get clogged up. Normally what clogs these condensation drain pipes is algae and crud growing in the pipe. It will usually block or clog the primary condensation drain causing the water to back-up in the unit. The water eventually finds its way to the secondary or emergency drain pan which should also have a condensation drain pipe attached to it that drains out the water when the primary condensation drain pipe gets clogged.

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Pipe Design for Protection

Water Dripping from Air Conditioner

Condensation Drain PipeThese two different condensation drain pipes should be distinctly different from one another. One should drain out in the flower garden or at the base of the house somewhere. The other should drain over a window or someplace where it will be recognized when it is dripping water. This is a warning sign that the primary condensation drain pipe is clogged and needs to be unclogged.

As a third measure of protection to prevent severe water damage to a ceiling a float switch is usually installed in the secondary pan so if it begins to overflow the float switch will kill the unit making it inoperable for use until the drains have been unclogged returning the unit to normal operation with all condensations drains open and freely draining condensation. Without regular maintenance these pipes can become clogged. Furthermore, this can end up with water damage from the pipes being clogged.

Diagnostic Checks

Water Dripping from Air Conditioner

There are different methods of unclogging condensation drains. It is recommended that you call an HVAC Technician to unclog the drains because the unit could have another related problem that causes units to flood and a quick diagnostic check by a qualified HVAC technician will ensure this problem does not exist and it is actually a clogged condensation drain. As noted above, air conditioner maintenance checks are important.

A special tool that uses pressurized CO2 cartridges to blow the line is used sometimes while other times a shop Vac can suck the muck out of the line. Water hoses can also be used to flushed the line although one must be very careful because you can actually cause reverse flooding and cause more damage than a clogged condensation drain ever could.

Condensation Drain Pipe Termination

Water Dripping from Air Conditioner

Find where the lines terminate outside the house and make sure the ends or not plugged by dirt or something else. Slugs or snails love crawling inside of the pipes and they can also cause a clog so make sure the pipe is up a little and not in the dirt of the flower garden. Good luck!

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Water Dripping from Air Conditioner