How Do You Size Ductwork?


Quick Answer

To size ductwork, calculate the CFM needed for each room, then calculate the friction loss rate. Measure the duct size using a duct calculator and install the appropriate duct size connections.

Continue Reading
Related Videos

Full Answer

Perform a whole house and room-by-room load calculation to calculate the required CFM as it will affect the entire sizing of heating ducts. Determine the exact available static pressure for the duct system by deducting pressure drops by any components from the external static pressure of the blower. Measure the total effective length, then multiply the available static pressure into 100 and divide it by the total effective length to get the exact friction rate. Using a duct calculator, size the ductwork based on friction loss and CFM.

Learn more about Heating & Cooling

Related Questions