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BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22008
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I have a Trane HVAC

Resolved Question:

I have a Trane HVAC, w gas heat.
I noticed that the condensation is coming out of the pipe on the outside of the house.
I think this is the emergency drain,
because I found the main drain under a sink.
The confusing thing is that there is no water in the pan underneath the system,
where it would normally overflow, and run out to the outside.
So Im confused.
How can this happen?
Submitted: 3 years ago.
Category: HVAC
Expert:  BillyHvac replied 3 years ago.

Have you actually traced the pipe to the point of origin?

There can also be a pipe from a second drain on the indoor unit that is slightly higher than the primary.

Customer: replied 3 years ago.
The pipes coming out of the system in the attic
Are side by side.
The one that is suppose to drain into to drain under the sink in the house
Has the pippe coming up in a t out of the system so you can pour
Bleach in to keep it clean. There is air blowing up out of that pipe.
Expert:  BillyHvac replied 3 years ago.
and the second pipe comes out of the unit and drains outside?

And this is the pipe drining water outside?

Customer: replied 3 years ago.
The second pipe is the one w the t and it drains outside and connects to the pan to drain outside.
But there is no water in the pan.
I turned the temp down to see if I could get
The water to come out of the outside pipe.
And the compressor is kicking off.
I can go outside and flip the breaker.
But it goes off after 3 minutes.
Customer: replied 3 years ago.
The unit is a Trane XE 1200. Is that old?
Expert:  BillyHvac replied 3 years ago.
do you see 2 wires going to the drain pipe?

Customer: replied 3 years ago.
No wires on the drain pipe.
The system is now running.
To clarify.
2 pipes coming out of unit in attic.
One goes to inside drain. It has the t and blowing air
Out of the top of the t.
Another one goes out side and drains the pan under the unit.
No water in pan.
Expert:  BillyHvac replied 3 years ago.
Yet the pipe from pan has no water at the drain outlet in pan?

Customer: replied 3 years ago.
Yes. That is the Wierd thing.
I'm trying to get water to come out of either pipe right now. But I guess it's not hot enough outside.
It's not draining under sink or coming out of the pipe right now.
Customer: replied 3 years ago.
Now it is running out of the pipe outside over window.
Not running through drain under sink. No water in pan.
Customer: replied 3 years ago.
I guess it is stopped up on the internal drain and needs to be cleaned out.
Is there a way I can do it myself?
Expert:  BillyHvac replied 3 years ago.
Thank you for being patient with me.

The summary is this:

The drain to the sink is the primary. The other is a secondary. The only time the secondary drains is if the primary gets pluuged or slow.

If the pan is dry it is perplexing as that is where the secondary pan drain is. Now if the secondary came from the ac unit but 1" higher it would make sense. That would mean the primary was plugged but the secondary was draining.

There is also a possibility that there is water going in the pan but is drying quickly in the attic heat.

At this point I would shop vac all the drain lines and watch the unit drains for a couple days to see if it persist
Customer: replied 3 years ago.
Do you just stick the shop vac down the hole of the t pipe and blow.
It's ok the the other side of the t goes back into the system?
Expert:  BillyHvac replied 3 years ago.

You can either blow or vacuum.

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