Ductwork in your house is one of the main sources of loss of efficiency with your HVAC unit. If you are installing a completely new system, the contractor will have to map out:

· Ducts: to ensure that the air is being efficiently circulated throughout your home.

· Vents: so it's  send the air out correctly, and it must be determined if these vents will be in the ceiling  , the floor or the wall .

· Floor vents: Ensure they are not going to be blocked by furniture or other objects.

If you are using existing ducting, it will have to be inspected. Proper ducting loses around 2% to 5% of your energy. Old, leaking ducts can lose 50% or more. A contractor will need to have the ducts inspected and replace any parts ahead of time. If you are changing the size of your HVAC system because of significant changes to your home, you might need to replace the ductwork regardless.