Radial system
Perimeter-loop system
Extended-Plenum duct system
Reducing-Trunk duct system
R-value
Provides the best performance when properly sized, the pressure drop is maintained from one end to the other due to decrease in trunk size.
A number that is used to indicate the ability of insulation to resist the flow of heat. The higher the R-value the better the insulating ability.
Uses round or rectangular trunks for the main supply and return, the ducts remain the same size and can be installed in a crawl space or attic.
Used in structures built on concrete slabs, it has a continuous duct embedded in the slab.
Each perimeter outlet is fed directly from the supply air plenum. The duct work can be installed in a concrete slab, crawl space or attic.