Design the Ventilation Early On. Before you can install any sort of ductwork, you’ll need to work out your load calculation. …Pick the Right Ducting. There are a couple of options you can choose when it comes to ductwork; sheet metal or flexible fiberglass hose.Pick the Location for Your HVAC First. Pick the most convenient locations for your exhaust pipes and other large parts. …Avoid Long Runs and Bends. Any bend, whether it’s sealed properly or not, will affect airflow. …Work With Existing Ducting. If you already have existing ductwork it is sometimes easiest to incorporate this into your new system.Make Sure to Seal Properly. If your ductwork isn’t sealed right, you could be losing up to 20% of your conditioned air. …Commission the System to Check Airflow. Once your ductwork is in place run a final check. Get your HVAC unit to check that airflow levels are right.