Duct sizes contributing to high humidity?

[Shophound]

Shophound, thanks for the reply. Is there a way to actually measure the supply side to determine if I have a problem there as well?

Backpacker

What has been missing in all this discussion so far is any person in your home performing a Total External Static Pressure (TESP) test. This test can find more airflow problems in a shorter amount of time than any "guess and check" method.

Visual inspection of the supply ducts can advise a tech of potential problems, such as leakage, kinked and/or sagging runs, duct sizes, length of runs, etc. But you need someone competent who can do both a visual assessment AND understand results of a TESP test. AND then know how to advise you accordingly.

What type of duct material does the problematic system have?