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Discussion Starter · #1 ·
I currently have condensate entering my HVAC secondary drain line even though my primary drain line is not clogged. The HVAC unit itself is balanced, so condensate is flowing to the primary drain port, but the water is leaking from the unit into the secondary catch pan prior to entering the primary drain line. Any ideas on why the water is not entering the primary drain line as designed?
 

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I think this is one of those situations where someone will have to be there. When you say the furnace is "balanced" do you mean tilted down so that the condensate runs to the corner with the primary drain? And when you say "but the water is leaking from the unit into the secondary catch pan prior to entering the primary drain line" do you mean secondary drain line?
 

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Discussion Starter · #5 ·
Yes, the unit is titled on both axis so the condensate flows directly to the primary and secondary drains. (I actually have a level sitting on top so I can visually confirm that the unit hasn't shifted.) However, the condensate never enters either the primary or secondary drain lines. It drips directly from the unit, mainly around the primary drain line.
 

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Does the plastic drain fitting (exit) from the furnace have knockouts that are still in place? Something is stopping the water from going out and leaking out around the fitting!
 

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Discussion Starter · #7 ·
The primary is completely knocked out (i.e. open) and the secondary has a half knock out in place across the lower half (the top 50% is open).
 

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If the drain has negative pressure you would just have to remove that cap on the left side. And seal the fitting on the right side. Then it will drain. Unless you have a bad primary pan. The picture is so dark I can’t tell which way the equipment is set up to tell if it’s negative pressure causing your issue. If you backed up a little bit when taking your picture I might be able to tell.
 

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That was my next suggestion - the cap on the vertical on the primary line may need to be removed. Some vertical "cleanouts" have caps but other verticals are not cleanouts - they are pressure equalizers.
 

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Discussion Starter · #10 ·
I have removed the primary line cap and will see if anything changes. Meanwhile, I tried to take another photo (see attached). Sorry, I can't move any further back. Thank you for the ongoing discussion!
 

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If your air flows in the direction of the red arrow you most likely will have to seal the elbow to the right of the drain as well. It’s hard to be sure of airflow from that picture. If it flows in the opposite direction then disregard having to leave cap off. And seal around the two drain pipes with something like cork tape
 

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Discussion Starter · #12 ·
Airflow is in the opposite direction of the red arrow (i.e. air moves from right to left facing the unit). Also, I slowly poured one gallon of water into the condensate pan under the coils. The water moved to and drained freely through the primary line. So I now know the pan is not cracked and the primary is not clogged between the unit and the cleanout.
 
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