Furnace drawing condensate into cabinet, but drain is not clogged.

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Tracy Baker

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Hello everyone!

I have one of those split-unit setups where an A-frame heatpump evaporator/condenser coil sets atop a dedicated furnace with heat strips. So the furnace blower is also the blower for the AC. When I'm running the AC, the furnace blower is sucking moisture into the furnace cabinet. The evaporator drain pan is draining through its drain line properly, but condensate is being overpowered by the blower and sucked into the cabinet. It's caused some rot , but not much, and I'd like to stop this before I'm tearing out floor. Any advice would be greatly appreciated.

Thank you, all.

Tracy
 

kok328

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Is the drain pain on the negative or positive side of the static pressure in the cabinet?
Is there a P-trap installed on the condensate drain line?
 

Tracy Baker

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Thank you for your reply!

If I understand you correctly, I would say both. It is a trough-shaped affair. Sort of like someone fried a rectangular doughnut, sliced the top off, and then dug out the bottom half like a canoe. The entire rectangular bottom of the coil rests in this trough with water collecting inside the coil and outside. The drain for the trough is outside. I assume the coil allows water to pass under it, or that there are some kind of stand-offs in the trough so that inner water can get out. Perhaps I can plug the drain line and pour water in the outside to verify that it can flow under the coil.

There is a P-trap in the drain line.
 

kok328

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Sounds like a Lennox. I hate the setup you've describe for the very reason that your having.
Yea, the water finds its way around the coil but also collects a lot of crud.
Best you can do is pour some really hot water into the pan and hope it comes out the drain.
I'd opt for a modification that allows you to remove the drain pipe for regular maintenance.
 

Tracy Baker

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Thank you. I went outside and duct taped a Shop Vac hose to the end of the drain line, and with it sucking hard on the line went inside and poured a gallon of hot water and bleach down the hole. I’ll give it a day and see if the moisture decreases. A lot of goop came out of the line, but it was draining on its own before I began the operation.
 

pjones

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Thank you. I went outside and duct taped a Shop Vac hose to the end of the drain line, and with it sucking hard on the line went inside and poured a gallon of hot water and bleach down the hole. I’ll give it a day and see if the moisture decreases. A lot of goop came out of the line, but it was draining on its own before I began the operation.
Wash that bleach off that coil really really well.
 
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