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Sunday, April 8, 2012

Have you checked your air conditioner's drain lately?

I used to live in a house which had an interesting little quirk outside its guest bedroom. Any time you were in there while the air conditioning was on, you'd hear this "drip, drip, drip" sound outside. Naturally, that connection wasn't made right away. At first, it seemed random, and later on, I figured that it was associated with the A/C running. It would start up a bit after the system came on, and would run for a bit after it stopped.

I figured this was normal. There's moisture in the air, and when you cool that air down, it's going to dump some of that since it can't hold as much moisture at that temperature. It has to go somewhere, so why not let it go into the flower bed next to the house? The audible dripping even made sense, given that the A/C box was up in the attic and it had a 10 foot drop to the ground. You could see it if you happened to go outside while it was running.

This went on for about seven years. Then, one day... no dripping. Well, no dripping outside, that is. Instead, the moisture decided to start draining into the bathroom immediately underneath that part of the attic where the A/C box was. Okay, now we have a problem.

Some nice HVAC repair folks came out and said that no, these things are not supposed to drip on the outside like that. When they do that, it's because the moisture has been going into a pan under the unit, and then that pan has filled up to the point where it can enter a pipe. That pipe then leads to the outside, and that's when it starts dripping.

But none of that is ever supposed to happen. Instead, the system is supposed to drain straight into the plumbing in the house. I had no idea what he was talking about, so he opened the door under the bathroom sink and showed me this:

Drain and tee

Did you know there was a tee connection underneath a bathroom sink for an air conditioner condensation drain? I sure didn't.

Our system was supposed to drain through that in normal operation. You were even supposed to hear a little "glunk, glunk, glunk" as the water slipped down the drain, just like when you use the sink normally. But, at some point, that drain had become clogged. This meant the water started backing up into the pan.

Big deal, right? Well, yeah, it is a big deal, because some of those pans are made out of a material which will rust. Eventually, it will corrode to the point of having a hole in it, and then gravity will do the rest. Soon, you will have a new shower head in your bathroom ceiling.

Given that the A/C had been dripping outside even before we bought that house, who knows when it had been clogged. It might have been doing this for years before we showed up. Maybe it *never* worked properly. That house wasn't too old, and it's possible that it had always been clogged.

The HVAC guys wound up doing a lot of work. I think they even replaced the whole unit since it was integrated with the now-unusable pan. The whole thing was a ridiculous amount of money considering that it was a double failure of two simple things: a water drain and a water pan.

Wet switch

To their credit, their new installation included a water alarm in the pan. If, for some reason, the proper drain becomes clogged in the future, that alarm will go off and it will disable the A/C. It'll get nice and hot, and someone will go up to investigate. They'll see the "this thing has a wet switch" sticker, then look for the switch, find the pan, and react appropriately... I hope.

So no, ignorance is not necessarily bliss.