AC Condensate Line Problem

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Gerrha

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I have noticed a few discussions on this topic, but the typical answers are less than satisfactory to me. In my case, I have two AC air handlers, which are located in the attic, 14-feet above the single-story living space. The condensate lines from each air handler join together into a single PVC pipe that descends down into the drain of a sink in a spare bedroom. This single condensate line enters the sink drain line above the trap and just below the sink itself. I have to say, in hot humid Houston, this scenario is an absolute disaster.

You know what happens next. The ubiquitous ever-present white slime blocks the trap, but the condensate keeps on coming. It fills the sink, overflows the sink, and then floods everywhere. It has destroyed the bathroom cabinet, damaged the drywall and molding in the bathroom, and extended out into the bedroom where is has damaged the molding and carpet. Pouring Clorox down the sink on a regular basis is a no-go because I have a septic system. I have been using a supposedly septic-safe product called Pequa. It works, but so what? I am over inspecting the spare bathroom sink on a weekly basis looking for water and pouring Pequa down the drain. If I go away for the weekend, I am in danger of flooding. In other words, I am tired of covering up what is clearly poor design.

My thinking is to relocate that condensate pipe straight through the wall to the outside where it can dump all that junk on the ground. It might be an eyesore out there, but I can live with that compared to the mess I now have. Does this sound like a reasonable solution to the problem?
 

WorthFlorida

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Are the air handlers on a drip pan for overflow should the main drain plug up? There is us a separate drain for the overflow going straight out to the soffit. Rerouting the main condensate straight out through the soffit is no problem, just be sure you have the proper AC condensate trap. You only need to go straight out and not have it turn down into another pipe to the ground. I've seen where at the facia the condensate lines dumps into the rain gutter.

The main source of the slime is from the coil drip pan. Nasty things grow in there. To clean use AC coil cleaner. Coat the coils as much as possible. Some are advertisEd as rinse free but it will really stink up the house unless the condensate does the rinse. I like one that use water as a rinse. You can use the tank sprayer to rinse off the coils. As you are cleaning you can use a shop vac to suck up the water laying in the drip pan.

There are pellets for coil drip pans to minimize slime build up and cleans the condensate drain. https://www.homedepot.com/p/AC-Safe-Air-Conditioner-Pan-Tablets-6-Pack-AC-912/100665383


 
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Gerrha

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Are the air handlers on a drip pan for overflow should the main drain plug up? There is us a separate drain for the overflow going straight out to the soffit. Rerouting the main condensate straight out through the soffit is no problem, just be sure you have the proper AC condensate trap. You only need to go straight out and not have it turn down into another pipe to the ground. I've seen where at the facia the condensate lines dumps into the rain gutter.

The main source of the slime is from the coil drip pan. Nasty things grow in there. To clean use AC coil cleaner. Coat the coils as much as possible. Some are advertisEd as rinse free but it will really stink up the house unless the condensate does the rinse. I like one that use water as a rinse. You can use the tank sprayer to rinse off the coils. As you are cleaning you can use a shop vac to suck up the water laying in the drip pan.

There are pellets for coil drip pans to minimize slime build up and cleans the condensate drain. https://www.homedepot.com/p/AC-Safe-Air-Conditioner-Pan-Tablets-6-Pack-AC-912/100665383


Yes, both air handlers are in their own drip pan. One air handler has a liquid level switch in its condensate pan that in theory, I guess, will shut the system down should that condensate pan build up liquid. The other air handler has a similar opening on its condensate pan, but no switch. Rather, it has a PVC pipe connected there that descends down and tees into the outlet line of its drip pan.

This area is covered with insulation, but both drip pan lines appear to run individually over to the soffit where they turn down and exit the soffit with about 6" of exposure, pointing straight down. I do not see a trap, on either line, but maybe they are hidden in the insulation. On another note, I also have two hot water heaters up there and they too are in individual drip pans. Their drip pan outlet lines run to an exterior wall, descend down, and exit the wall about 12" above the driveway. Two years ago, one water heater failed, and its outlet pan was insufficient to handle the water, causing damage to the ceiling drywall. I really have to question the logic of putting water-containing equipment in an attic, but it seems to be standard procedure in the Houston area.

Normally, I have a company come in twice per year and do maintenance/check-up on the AC systems. I have not followed them around to see what they do up there, but at the same time, I am not confident that they are opening up the air handlers and cleaning the coils. Opening up those air handlers exposing the coils is a job in itself. They even appear to be sealed with mastic. I tried those pellets sold at Home Depot, but the thought of opening up the air handlers on a 6-week cycle just seems to me like there must be a better way.

If I relocate the condensate main line to the exterior soffit area, you mention a trap. Is a trap needed to keep the Houston nasties (and there are way too many of them) out of the attic?
 

Jeff H Young

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Im guessing thats how we drain upwards of 3/4 of our condensates plugged up lavs is a problem why do they keep pluging up? but nothing unusual or problematic about draining condensates to a lav or sink
 

WorthFlorida

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In my last two homes in Florida, the trap is outside. When the homes were built a 3/4" PVC drain line goes under the slab. A 90 degree turn to outside of the footing, then another 90 degree up about 8-10" above grade, two more 90's to make a trap. You cannot have two traps, it won't drain.

With a high probability of flooding in the Houston area, an attic install will save the appliances.
 

John Gayewski

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Your trap(s) should be in the attic just below the coil(s). No reason not to dump it outside.
 
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Jeff H Young

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if it was plugging up the indirect line it would come out the secondary line over a window or door way or you put in a Safe T switch that shuts the a/c off. basicaly get to the bottom of plugged up sinks and you wont have an issue.
the emergency drain pans normally have no water in them no way to trap that line
 

WorthFlorida

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My last home the first floor AC drained always plugged up with slime. Not enough gravity where as the second floor AC drain never had a problem. I used to do is with a garden hose dragged into the house, shoot water into the condensate drain. Usually the main drain will have a tee with a cap on it for cleaning.
 
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Jeff H Young

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the cheap easy fix yea pop it out the wall. not very good . itll happen again my guess I think in the south failure to maintain it will repeat.
All I know is it dosent happen here to most homes . and the few people and homes Ive been involved in Florida do have problems if not cleanned proactively , you might go a year or more and one day you have a mess
 
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