Our split level main floor has poor air flow to one of the levels. This level has is ducted by a 9" dia duct positioned 1/2 way up the 30" vertical by 20" sq. plenum. At the top of this 30" vertical plenum are 2 - 8"x 18" ducts coming out the sides. One of these feeds the basement and the upper level of the split level the other feeds the upstairs. Both of these runs feed by the 8" x 18" ducts function fine with noticeable air flow.
The 9" round duct halfway up the vertical plenum immediately 90's down then 90's out to exit the basement wall. It now is under the garage floor for a couple of feet before it 90's again to pass through the basement wall into the crawl space below the level in question. Once in the crawl space it transitions into a 8" x 14" duct 8' long. At the transition there is a 5" dia. run for 4' to a 2" x 12" register and at the other end of the duct are 2 - 5" dia. 8' runs that terminate at the corners of the room with 2" x 12" registers.
My professionally uneducated guess is that there is not enough pressure in the plenum to push air into the 9" dia. duct especially with all of those 90's. I tried to build a diverter out of cardboard to direct more air towards the 9" but that did not seem to help much.
Do you think I can install a 8" booster inside the 9" duct before the 90's to help pull and push air into this run?
We are only having this issue with HEATING. This is the lowest level above the basement so it tends to stay cooler. I'm hoping if we go with a booster I can tap into where the booster would only run when heat is called for.
Sorry for the long post, I'm hoping someone can provide some advice. Please let me know if you need any addition info.
Walter
The 9" round duct halfway up the vertical plenum immediately 90's down then 90's out to exit the basement wall. It now is under the garage floor for a couple of feet before it 90's again to pass through the basement wall into the crawl space below the level in question. Once in the crawl space it transitions into a 8" x 14" duct 8' long. At the transition there is a 5" dia. run for 4' to a 2" x 12" register and at the other end of the duct are 2 - 5" dia. 8' runs that terminate at the corners of the room with 2" x 12" registers.
My professionally uneducated guess is that there is not enough pressure in the plenum to push air into the 9" dia. duct especially with all of those 90's. I tried to build a diverter out of cardboard to direct more air towards the 9" but that did not seem to help much.
Do you think I can install a 8" booster inside the 9" duct before the 90's to help pull and push air into this run?
We are only having this issue with HEATING. This is the lowest level above the basement so it tends to stay cooler. I'm hoping if we go with a booster I can tap into where the booster would only run when heat is called for.
Sorry for the long post, I'm hoping someone can provide some advice. Please let me know if you need any addition info.
Walter
Last edited: