# Drain line sweating in attic



## gastek (Mar 29, 2011)

My folks have their air handler in the attic and I had to replace part of the drain line because someone stepped on it and cracked it. I noticed that the drain line sweats. Is this common? The house is in FL. In my house the air handler is in the garage with the drain line going under the concrete. So obviously I have no idea if my line sweats.


----------



## flashheatingand (May 3, 2008)

quite feasible. Is condensate run in metal pipe? If, so change to PVC


----------



## flashheatingand (May 3, 2008)

Does condensate drain alright?


----------



## gastek (Mar 29, 2011)

Yes it is PVC. 

Good question on it draining right. I believe that it is but I will double check this today.


----------



## TAHomeRepairs (Jun 18, 2012)

Very common for them to sweat. I recommend insulating with foam pipe wrap whenever I see this.


----------



## gastek (Mar 29, 2011)

System is draining fine. I am going to wrap it as suggested.


----------



## flashheatingand (May 3, 2008)

Never seen pvc sweat, but...


----------



## beenthere (Mar 5, 2009)

flashheatingand said:


> Never seen pvc sweat, but...


OP is in Florida. Hot and humid.


----------



## flashheatingand (May 3, 2008)

I get that. I can imagine the condensation forming on metal pipe, but, not plastic. It makes a good insulator. Would the schedule 40 pipe make a difference? Not doubting, just, I would not think that there would be enough heat transfer through the plastic, to cause condensation.


----------



## MarkJames (Nov 25, 2012)

Here in humid Washington, DC, I've seen pvc bead and sweat in attics. Cold pvc drain line + humidity = condensation & dripping...and the P-trap is sometimes just outside the pan, so it drips on the floor. I tried to explain that to one client, and to insulate it, but their expert hvac guy kept coming to drain the line that wasn't clogged. Go figure.:whistling


----------



## beenthere (Mar 5, 2009)

flashheatingand said:


> I get that. I can imagine the condensation forming on metal pipe, but, not plastic. It makes a good insulator. Would the schedule 40 pipe make a difference? Not doubting, just, I would not think that there would be enough heat transfer through the plastic, to cause condensation.


In a hot humid area like many areas in Florida are. The A/C takes out a lot more moisture. So the PVC trap gets a lot colder then in most areas.


----------



## Big Shoe (Jun 16, 2008)

Yes pvc does sweat in attics if not wrapped/insulated here. I've fixed enough drywall to see what it does.


----------



## flashheatingand (May 3, 2008)

MarkJames said:


> Here in humid Washington, DC, I've seen pvc bead and sweat in attics. Cold pvc drain line + humidity = condensation & dripping...and the P-trap is sometimes just outside the pan, so it drips on the floor. I tried to explain that to one client, and to insulate it, but their expert hvac guy kept coming to drain the line that wasn't clogged. Go figure.:whistling


With that situation, why not put the trap outside at the termination point?


----------

