Reply #4: I know it is supposed to work, but in my mind I see the air blasting

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up through the ducts, finding one blocked and trying to go someplace else to escape, but it "runs into" all the other hot air still being forced up and....well I just imagine all the hot air tumbling around in the ducts work. Maybe it's just me! I did go ahead and close off the empty room vents though. Thanks, Cathy