How do I reduce duct leakage?
A great way to improve your systems efficiency is to caulk all openings in unconditioned space (basement, attic, etc.) and to tape all seams of your duct and round pipe. When caulking, make sure you get a caulk that is meant to handle extreme temperatures; in fact, they make a caulk specifically made for HVAC purposes. You can use standard duct-tape to tape your seams, but using the silver, shiny smack tape is much better as it seals longer and looks much better.