bironacad
Platinum Member
South Carolina? Are you worried about heating or cooling? Money or performance? Where is the duct carrying the air to? I was in HVAC business but need to know what you are trying to accomplish. Here duct work in an unconditioned space must be insulated to a level similar to the wall it is against, if the wall is R 12 the ductwork gets R12. The duct in your picture is insulated a tad. If you are worried about costs for heating and cooling 1/3 of your heat loss/heat gain happens through the top portion of a basements uninsulated wall. Blocks having hollows allow for cold air to sink all the way to the bottom of the wall. I live in a climate where we by law had to insulate to two feet below grade, (dirt below two feet is pretty good) now our building code states that we insulate the entire wall to min R8 right to the footing. If you are having troubles with air flow you might want to get someone with air distribution system experience to give it a look. Air duct is limited to the smallest restriction, once you have reduce a size going back up will drop air velocity and inhibit performance. Your climate is moderate?
Hope this helps
Hope this helps