dripping plenum

[jg0731]

I have a condo with 10-20 year old equipment. Forced air, gas furnance and gas hot water heater. Central A/C unit outside. Recently, the plenum began sweating whenever I run the a/c. The plenum's condensate line is a few feet of ABS pipe (1/2 inch or 3/4 inch) with a few elbow turns in it. I'm thinking either the plenum or the condensate line
is blocked, which I guess can happen after many years. I have a pvc pipe cutter, which I imagine would cut the ABS pipe just fine. I went to Home Depot and Loews, but I couldn't find such thin ABS pipe. Do I just cut the pipe off and then run a snake down the drain and up to the plenum? Would I then just clamp the slit pipe back together? Should I open the plenum, and how would I do that? Should I clean the condensate line and plenum with Lime-Away, with a tool, or with suction from a wet-vac? As you may have guessed, this is not my field. I appreciate any advice anyone can offer.
Thanks.

[troyorr]

It is possible, on a 20+ year old unit, that your condensate pan has finally rusted through. The only way to tell for sure is to have the indoor coil removed and the pan inspected. Hirer someone qualified to do this for you. You can cut the ABS and when you finish cleaning out your drain, install a rubber repair coupling to put it back to gether. There is no pressure on the condensate so you will be alright. Get your repair coupling from a plumbing supplier if your local Warehouse stores don't carry them.

[markco]

If plenum is sweating, it sounds more like an airflow problem. If water is dripping down the side of the furnace, then it's the condensate line plugged up. Check to make sure all the registers are open, and none of the returns are blocked. Also, on the trunk lines, there may be a lever for the balancing dampers. Make sure these are open.http://ww2.imagewiz.net/images/hvactalk/130387_5202-1.jpg

[Edited by markco on 09-24-2004 at 12:55 PM]