Air Conditioning Condensate

Your air conditioner does two jobs: It cools down the air and it dehumidifies the air. If you live in a dry climate, you want the AC to dehumidify as little as possible because it uses extra energy and makes you spend more on lip balm and hand lotion. If you live in a humid climate, you really want it to do that second job as well as it can to keep your indoor air dry and comfortable. But where does all that condensate go?

In most homes, it goes outdoors through a pipe, like the one above. Sometimes there's a little pump that pumps it out, but most often it drains by gravity alone. Occasionally that condensate line gets clogged. This happened at my condo last week. (We live in Atlanta, Georgia, a mixed-humid climate.) Gunk in the pipe built up to the point where it was barely draining. We could run the AC for a little while and then we'd have to turn it off again.

This past weekend I tackled the problem. One of the best ways to do so is with good old air pressure. If you can close off all escape routes except the one in the direction of the clog, you can shoot positive pressure into the pipe near where the indoor unit is located. That should blow the clog out the other end. In our case, that wasn't an option because our condensate line is connected to our upstairs neighbor's air conditioner, too.

So I got out my little wet-dry shop vac and set it up to suck the gunk out at the end of the pipe. The photo below shows the setup.

I was hoping to avoid a trip to the hardware store, so I used red duct tape to try to make an airtight connection between the shop vac hose and the condensate line. It didn't work.

I took the shop vac hose with me to the store and bought some fittings in the plumbing department. I hooked it all up (photo above) and got a nice, airtight connection this time. With the taped connection, I got maybe half a cup of water out of the pipe. With the airtight connection, I got the bucket full of crud you see below.

If you really want to see how bad it was, watch the short video below and you can see my wife pouring it out.

Yes, all that gunk was in our condensate line. One problem with condensate lines is that algae can grow in them. In our case, there's also a lot of sediment in that bucket, possibly from a corroded evaporator coil. We replaced our AC in 2009 and the condensate line hasn't been cleaned since then, so some of that crud could have been from our old unit.

If you haven't thought about your condensate line lately (or ever), this would be a good time to do so. You can have your HVAC company make sure it's clean, or you can get a shop vac and do it yourself. To keep it clear, you can use an algaecide that's safe for air conditioners. Your HVAC company can recommend one for you. In hot-humid climates like Florida especially, clogged condensate lines are a frequent problem.

A little preventive maintenance now could save you thousands of dollars in water damage repairs and the loss of your air conditioner when the heat really cranks up.