Here at Designair of Texas LLC, we use ACCA's Manual D to deliver a duct design that that will distribute air proportionally based on load requirements while keeping the overall static pressure at optimum levels. Duct systems need to be designed based not only on the heating and cooling load calculations from the Manual J, but also the different types of materials and metal fittings being used and the geometry of the duct layout. This will ensure that the CFM requirements for that individual room are met by properly sizing the ductwork according to the rules of Manual D.

There are also incorrect assumptions about CFM requirements. When designing duct systems, it’s important to not use “rules of thumb” as many people call it. For example, a lot of contractors believe that the required CFM equals the floor area multiplied by a random number, or that a specific duct always delivers a certain CFM. That couldn’t be further from the truth. Duct design requires a lot of calculations and thought so it’s best to leave it to the experts. Contact Designair of Texas LLC to get your duct system designed the correct way!