Return Air Duct: Incline Necessary?

moiety

Hey Folks,



I'm thinking about remodeling a basement space occupied in large part by a gas-powered forced air furnace and its associated ducts and tentacles. Most of them are high enough towards the ceiling not to be too bothersome, except for one of the three return air ducts.



The other two return air ducts run in parallel with the joists, so they are embedded within and are essentially "in" the ceiling. The third return air duct, our problem child, runs perpendicular to the joists, so understandably it needs to be lower.



HOWEVER, for reasons unclear to me, it also has an incline: while the end connecting to the intake grille is flush with the bottom of the ceiling joists, the end near the furnace is almost a foot lower. The duct itself is consistently 32" x 8" and runs 11 feet.



***



My question is: Is there something inherent to the design of the return duct that absolutely requires it to have an incline? Or can I lift it and straighten it out, so that the headroom directly under it is a constant height? My confusion is further fueled by the fact that the other two return air ducts do not have an incline -- just this one.



Your insight is appreciated!

Eugene_Silberstein

No Incline Needed!

Feel free to level as you wish.

STEVEusaPA

I agree

Probably just a little laziness from the Installer (finish quicker or go get one more piece?), or maybe there are some takeoffs coming out of the top of the return.

billtwocase

word of advice

i wouldn't add a return in the basement, if that is the what you have in mind. No better way to create a negative pressure in a building other than an exhaust fan

will smith_4

Duct inclination

Having the duct on an angle made it easier for marbles/crayons/cats to get back to the furnace when they fell in the return grilles-