Minimum height for supply trunk line?

[ColdInSeattle]

Hello,
Is there a minimum height-width ratio for a supply trunkline? I need to run about 140 in^2 through my trunk line and I'd prefer to do something like 4x35 rather than 6x24. Will that have any negative impact on my system?

Thanks in advance!

[beenthere]

Yes, it won't move the air like you think it will.

Your contractor should know this. And know what ratio he can use.