I recently built a home in summer of 2010, and my air conditioning this summer (2011) is having a condensation problem on the OUTSIDE of the plenum and ducts (at least for the first 3-4 feet running past the plenum).
I have a trane furnace and air conditioner, it is 3 zones total one for the basement, main floor, and upstairs) so there is three main branches going out of the plenum with dampers.
The furnace is located in my finished basement in my mechanical room, and there is no unusual humidity problem down there or anything like that. I have even run a dehumidifier from time to time but it doesn't fix the problem.
The plenum itself condenses on the outside of itself, as well as one of the main branch ducts (that runs the most which goes upstairs up a flu chase) which also condensates on the outside for about the first 3-4 feet running out of the plenum. The condensation problems start at the beginning of the plenum in my mechanical room.
All of this drips on the floor making a big mess anytime the temperature gets above 90 degrees outside. To make it worse it drips on an electrical subpanel which I am worried about as far as shock hazard.
The plenum is NOT insulated inside (according to the installation HVAC folks) or outside in anyway, and neither is the ducts. They are sheet metal.
I have had the folks that installed the system take a look at it three different times, and I forked out a lot of money for an entire air conditioning / furnace system to them last year, and they have not been able to solve the issue.
I do know last year the builder "forgot" to have an air filter running in my air conditioner for the first month or so after construction. Could this be caused by a dirty evaporator problem? Or a low freon type issue? Or maybe just the fact that the ducts or plenum should have been insulated.
Other then that the drain line works normally and drains. The condensation is on the outside starting at the plenum and then disappearing.
Thank you for any help and advice. I am trying to ask for some expert help in guiding me in the right direction.
Thanks for your time and responses,