I’m in the process of remodeling my master bedroom and bathroom. I want to change the location of the door to the closet. Problem is that where I need to move the door to is where my cold air return is located. The wall I want to move the return to will require me to extend the duct work around a room that’s framed up in the basement. Also, the supply side runs parallel to the return on the side of the return that needs to be offset, however, where the current master bedroom return duct is boxed in between the floor joists it extends over the top of the supply side and is blocked off to where I could easily tap into it. My question is: could I simply run another trunk line parallel with the current duct work and tap in to where this return is blocked off? It wouldn’t be that hard to fabricate in this fashion but I want to make sure it would be considered a proper modification.
Also, the room this return will draw from is 14 x 14 with an 8’ flat ceiling. Thanks in advance for any help!
To match the air volume of a 14 x 14 return you can use a 14" round flex duct. That will be enough for 1000 cfm of air = to a 2.5 ton system.
I might have to run two smaller flex ducts from the trunk to the register because of the way the floor joists line up. That’s kinda the way it’s done now. The register is right over top of a joist and so they boxed in both joists and it’s drawing from both. The new location will have to be the same way except I need to use ducting instead of boxing in the area between the joists.
Because of the configuration, number of doors and furniture placement, it’s not really feasible to add an additional register. The easiest thing to do would to put it in the floor in front of the closet door but that would be tacky!
6" Flex= 120 cfm 7"= 150 8"= 200 10"= 400 12"= 600 14= 1000. 400 CFM per ton of cooling. I can convert all these into sq or rectangle dimensions if needed.
If that is the only return feeding the air handler its undersized. 17x8 = just over a 12" round and carries just under 800 cfm @ 0.1 friction per 100 ' of duct.
The air handler is located approximately center in the basement. The duct work connected to it measures 23” x 14”. It goes up and T’s to the trunk lines that run the down the length of the house on either side. Based on the sq/footage of this house and what I read on the internet, the system is on the very upper end of the recommended sizing. I suspect the house was built with a small unit originally.
