Removal all of existing supply ductwork in crawl space. Installing new R-6 flexible duct, 12 runs total all the way to supply plenum! Completely sealed and strapped. New return plenum off of furnace. New 16" return flex ran to new cut in by main living room (high volume. (20x25x1) and also replacing old return grille with high volume 20x25x1. Once complete with new duct system install we will do a combustion balance on system to maximize performance of the old equipment. 100% Guaranteed Satisfaction with a Lifetime Warranty!!! $7,280.00