Replace air return

[nmantas]

I have a thread in electrical about my sheet metal on wire issue as well as wires ran down the air return. I'd like to get the HVAC crews thoughts as well. This 12' joist lining is off the main return down the center of the house to the furnace on the other side of the house. Would I be able to delete the joist lining and replace it with 6" round off the shelf ductwork ran above the wires to eliminate most of my electrical conflicts? I know that the CFM capabilities of the joist void are massively larger than a 6" round but I don't really think it is needed for a single return register (the bedroom this return goes to only has one supply vent). Seems to me that the area of the slots on my register is far smaller than the area of a 9 inch circle. Thoughts?

 

[Major Woody]

The return must be sized based on CFM required. Then consult a table showing the CFM capacity of various sizes of duct. This is run in conditioned space so if round won't fit, rectangular likely will.