Fix-It Fred: Condensate Drain Cleaning

I enjoy fixing (most) things and extending the useful life of stuff as long as possible. I find the challenge of diagnosing and remedying problems mentally stimulating and gratifying. My family is more than willing to oblige me this pleasure. In fact, I am often greeted with a pile of broken items when I walk in the door after work. They have even created a designated spot on a shelf in the kitchen to store their damaged goods. Some may call me strange for enjoying what others call mundane; not my family, though. They call me Fix-It Fred.

Home ownership comes with many benefits. Also many headaches. Earlier this summer we were dealt one of the headaches: our air conditioner began malfunctioning. I devoted a considerable amount of time to troubleshooting the system and finding the cause of our warmly conditioned air. I determined the problem was in the outdoor unit, and one of only a few options at that. Each of those possibilities came with a large price tag, so we decided it was time to call in a service technician for a system analysis.

Long story short, the diagnosis was costly and we were left with two options. Option 1: replace the damaged parts. Option 2: for slightly more money, replace the entire unit. Since our current system is 10 years old, we opted for the new outdoor unit. The fact that the system also doubles as a heat pump in the spring and fall only made the decision easier. While I like to do my own home repairs and upgrades, I know my limits; replacing our outside air conditioning unit is beyond my capabilities.

Having someone else install an AC unit should be painless for me, right? Not so much. The project was scheduled in the middle of a lengthy, humid heat wave. As a result, the new system ran almost constantly. It pulled a significant amount of water out of the air. The first evening it ran I went into the basement utility room and was met with a large amount of water on the floor in front of our forced air blower unit. The condensate pan was full and spilling over everywhere.

Obviously, the condensate drain was not doing its job. It was a PVC drain and all the joints were glued together. I was eventually able to break free one of the joints. More water poured out (on my foot, of course). After changing my socks, I cleaned the p-trap in the condensate drain line the best I could. Since all the joints were glued, it was a rather difficult task. I did what I could and hoped for the best. The next evening, I checked the floor and found more water. Evidently my cleaning was not sufficient.

I tried to clean the drain line a couple more times with similar results. Eventually I took the drain line off and ran a temporary one, with no trap, directly into the floor drain so my floor would stay dry as I found a permanent solution. The solution I wanted was a way to make the p-trap easy to remove and clean, but remain water tight in order to prevent future leaks. I also wanted to maintain a routing similar to the current one so the drain line was not just laid across the middle of the floor.

Drain line routing behind the furnace, keeping the floor clean
Drain line routing behind the furnace

I went to the hardware store to see what was available that would suit my needs. I bought a new p-trap, since the old one was partially blocked and not cleanable. I also bought a threaded connection with rubber seals to put on the downstream end of the p-trap; this would make that end of the trap removable.

thread closed
Threaded connector, assembled
thread open
Threaded connector, disassembled

On the upstream end, I used plumber’s grease on two of the joints between the connector on the furnace and the trap so that it could be pulled off easily, but remained water tight. I needed to use it on two joints based on the routing of the drain line. I greased the vertical connection to the trap and the connection on the furnace so they were both removable. Had there been a simpler routing available, I could have greased only one joint. Just a note: plumbers grease works well as a waterproof seal in low pressure water systems, but it will not work the same for high pressure systems.


greased joints
Greased joints highlighted with red arrows

Since I used the grease, instead of glue, I wanted something to support the weight of the drain line. Without additional support, the joints may have rotated and the line would no longer have maintained its downhill path to the floor drain. To remedy this, I added a few j-clips to ensure the entire drain line was sloped correctly, and the joints that were not glued were not holding any weight.

J-clamp locations highlighted with red arrows

Now when it is time to clean the p-trap the process is simple. I unthread the downstream connector and pull the one greased joint near the furnace outlet apart to remove the p-trap assembly. Once that is removed, I pull apart the greased joint on the trap itself and am left with only the trap to clean.

trap asm
Greased joint on trap highlighted with grey arrow
Easy to clean trap

Cleaning only the trap section is a much easier job. I can now remove, clean, and reinstall the trap in under 20 minutes. I reapply grease to the necessary joints each time I assemble them, just in case. Since I have installed the new trap I have had no more water on the floor, my socks are dry, and my headaches over glued joints are gone.