Condensation on Air Handler and Supply Ducts
We live on the 15th floor of a vintage high rise building and had our a/c system replaced this spring. We have one horiztonal air handler in a ceiling which serves the front of the apartment (and is located near the front of the apartment) and is operating normally. We have a vertical air handler in a closet which serves the back of the apartment. It has a significant amount of condensation on the outside of the air handler and the visible supply ducts even though the closet door is open and we are constantly running a dehumidifier in the room. We've had the installer out numerous times and they've made sure that the holes that were drilled to the outside of the building and have been sealed. They insist that there must be a source of warm air coming from some kind of hole between the floors. Apparently, the floors are pretty thick concrete but there are honeycombed air spaces between the floors.
The installer's recommendation is that we tear out the ceilings (which are dry wall and dropped slightly from the original 10 foot height in certain places to accomodate the duct work) and insulate the duct work and insulate the air handler.
Does anyone have any thoughts on this? Obviously, it's a lot of work and expense to repair the ceilings and we don't want to push the condensation problem someplace else.
Is there anything else we should ask them to look at before we take this step?
Thank you so much.