View Full Version : Does cast iron p-trap sweat?

06-23-2011, 11:40 PM
Did a test yesterday of a tub installation. Ran cold water until it overflowed, then let out the drain. Did not detect any leakage. Great. But today, while adding a strap I noticed my hands got wet. I'm wondering if this indicates maybe I did have a leak or is it likely that the p-trap is just sweating?

06-24-2011, 05:37 AM
Anything will "sweat" if it is cooler than the "100% relative humidity" point for the moisture in the air. BUT, if the trap is that cool, everything else in the area should be also, so there should be other areas of condensation.

06-24-2011, 08:00 AM
Hi David,

Simple enough to find out, right? Fill the tub to overflowing again and then drain the tub again...use warm water this time. Use a flashlight to check around all seals at the tub waste and overflow assembly. Sounds like a leaker to me...I hope not!!

Good luck!

06-24-2011, 04:32 PM
After a day, it would be at room temperature, and unless everything else was wet from condensation, it's likely a leak.

06-25-2011, 12:07 PM
It did turn out to be a leak. I tightened the slip joint again (had to use pliers handles on the little tabs on the nut to get enough torque) but it seems to be ok now. There was also a drop of water in the basin area, so I also tightened the basket nut up too. Geberit had recommended redoing the silicone for the basket seat but I wasn't able to pry it up so thought I'd try tightening it up and that seems to have done the trick.