A/C & Furnace leaking water. Advice?

Feb 25, 2011
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So, we have a Carrier condensing furnace and blower, original to the house (2006.) It's also the blower for the A/C in the summer. (Kind of standard forced air setup, I guess.) It's on the second floor of the house, and water is leaking down into our kitchen.

I took the covers off the furnace, mopped up what I could, and looked around with a flashlight. It appears that condensation is forming on the evaporator coils (in the "outflow" area of the furnace) and dripping down into the rest of the unit, pooling, then leaking onto the floor (the furnace was installed before the linoleum, so it's just on top of subflooring). The evaporator coils (they look more like radiators to me, with the fins) are the highest-altitude wet thing.

It's been in the 80s for a couple weeks and peaked around 100 today, so the A/C unit is working temp-wise, but house temp is 70F with ~70% Relative Humidity. (Dew point at ~60F.)

Is it possible that our RH is just too darn high? (Get dehumidifiers?) Or could this be a problem with our A/C unit? (This has never happened in the 12 years we've lived here, and the current weather is not abnormal.)

TIA
 

boomerang

Lifer
Jun 19, 2000
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The condensation you're seeing is normal. You have a blocked drain line. There is a pan under the evaporator and attached to that pan is a drain line which provides a path for the water to be directed outdoors. That line is typically PVC and you should be able to easily identify it.

If you have a shop vac, you can try vacuuming that drain line from outside to remove the clog. Try to get the best seal you can and leave it running for a good 15 to 20 minutes. That's done here as part of normal AC maintenance.

Here, they tee in a stack in the drain line right by the air handler (furnace in your neck of the woods) so that periodically something can be poured in to eliminate any buildup of nasties in the line that could block it. They suggest homeowners use 2 cups of vinegar. The AC guys have some stuff they use which is probably more powerful. They also install a float switch in the line that will shut off the unit if the condensation builds up to prevent the situation you're experiencing. That would have saved you all this grief. Maybe you have one and it's not working. When we lived in the north, they were not part of a typical installation.

A small critter could have decided that line would make a good home and have it blocked from the outside. Once again the vacuum should deal with that.

Find the termination point of that drain line and go to town. If you can't clear it, it's time to call in the pros.
 
Feb 25, 2011
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Thanks!

I found the line from the evap coils and the condensation tray. It's clear as far as I can force a length of aquarium tubing, and if I pour stuff down it, it comes out the drain in the basement.

Also, the tray isn't overflowing or backed up. Either I'm wrong about the source of the water, or there's a hole/crack in the tray somewhere I can't see. Called a guy - will update with any info I find out.
 

boomerang

Lifer
Jun 19, 2000
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Yeah, please let us know. I'm now really curious what the cause is. I think a crack in the tray would be unlikely as would the tray being suddenly skewed out of level which could allow the water to run in the wrong direction.

Any water lines running in that area? Maybe it's not HVAC related.,,?
 
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Feb 25, 2011
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There's a water pipe running to the humidifier but that's fine. Nothing else. I have towels wicking the moisture away and a guy coming out Monday. Will probably point a heat gun at the hole in the ceiling later, after I remove the light fixture in the kitchen that had water pooling in it...
 

mindless1

Diamond Member
Aug 11, 2001
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I recently had the coupler to the fitting coming off the drain pan crack. $1 part, but only because I was able to get it off the pipe it was cemented to and reuse that pipe so I didn't need more pipe and/or a coupler for that too.
 
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What about the drain line from the humidifier? I assume you've got the humidifier turned off, right? I didn't mention it but I thought 70% humidity sounded awful high...
Humidifier is off. :)

The drain line from the humidifier links up with the drain from the evaporator coil overflow tray. Water flows just fine. :)
 

bbhaag

Diamond Member
Jul 2, 2011
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Whens the last time you changed the filter? I know it's an embarrassing question but earlier this year we had the same thing happen to our unit at work and it turned out to be a dirty filter. Once we changed it out the condensation stopped and all was good.
 
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Paperdoc

Platinum Member
Aug 17, 2006
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So far you say the condensate collecting on the evaporator unit is being collected by its proper tray and that the drain line to handle that water appears to be working no problem. So, are you SURE that the source of the water that alerted you at first really is from that evaporator? You have not said anything about the condensate generated by the furnace system. Now, if temps have been as you say for a long time, maybe that furnace has not does any heating for white a while. But in my case in a different area with much less heat outside, I don't have a central air system. Still, at least one a year I inspect and clean out the condensate drain system from the condensing furnace heat exchangers.
 
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Feb 25, 2011
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Whens the last time you changed the filter? I know it's an embarrassing question but earlier this year we had the same thing happen to our unit at work and it turned out to be a dirty filter. Once we changed it out the condensation stopped and all was good.
I change it every couple months. It was a bit on the dirty side, but shouldn't have been impeding airflow. (I removed it completely since it was soaking up water.)

So far you say the condensate collecting on the evaporator unit is being collected by its proper tray and that the drain line to handle that water appears to be working no problem. So, are you SURE that the source of the water that alerted you at first really is from that evaporator? You have not said anything about the condensate generated by the furnace system. Now, if temps have been as you say for a long time, maybe that furnace has not does any heating for white a while. But in my case in a different area with much less heat outside, I don't have a central air system. Still, at least one a year I inspect and clean out the condensate drain system from the condensing furnace heat exchangers.

That's possible. But the furnace hasn't been running for a couple months. I don't really want to disassemble the furnace far enough to take a look at the heat exchangers, unfortunately. :eek:

Suffice to say I will be asking a lot of questions tomorrow morning. :D
 
Feb 25, 2011
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There's a leak - it was crazy-low on refrigerant, and apparently the filter was restrictive enough that it was slowing air down and causing way more condensation than there should have been. Running the dehumidifiers actually prevented water from dripping all over. We're looking at (cheap) options for recharging/replacing now.
 

Mayne

Diamond Member
Apr 13, 2014
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first things first. Check your filter..is it dirty? Check the condensate line..is it plugged? If it is..give a good blow and make sure its not blocked up.