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Mystery Furnace Condensate Drain Line

Jerry Simon

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Are these furnaces twinned?

Might they have replaced older 95% furnaces with newer (relatively speaking) furnaces? Reason I ask is that quite often you'll see drain lines on a 90 exiting the furnace flue gas discharge line. We see where the plastic tubing is in the furnace but were does the other end go to?

Any humidifiers on the furnaces - or use to be?

I must say that it is odd that a tech would leave them if they were not needed anymore (unless it was cousin Billy-Bob that was the tech).

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The drains are needed for condensing furnaces. Maybe Terrance is correct: The tubes were used on the older condensing furnaces but are not needed on the replacement furnaces.

One other thing: In the top most photo, what is that little thing sticking out at the lowest extremity of the draft fan housing?


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These are 2003 furnaces, not twinned, just in the same closet; one serves the first floor, the other the second floor. In the one pict, where the drain line is in the almost-vertical position, that's the "natural" position of the lines.

I'm pretty sure the tops of these lines once connected to something that ain't there no more. They didn't connect to the bottoms of the inducers, though, where the yellow caps are; I know this for a couple reasons (even though I would think there would be drains there as well, as we see on lots of other furnaces).

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That's the in-line drain. It's supposed to connect to a nipple that projects (normally) straight downward from the right side bottom of that white exhaust vent coupler. It drains to the collector box and then into the air handler and out the side of the unit. Is it possible that the original coupler with the nipple cracked and was leaking and someone fabricated that one from a bunch of PVC pipe parts purchased at HD?



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