Adding additional return

[bhermis]

I have a 5 ton system with a single 18" flexduct return that comes in to the plenum box before the blower at a 90 degree angle. My tech wants to add a 12" flexduct return to service the other side of the house that will come in to the plenum box inline with the blower. There will be a dampener on the starting collar to regulate flow. Are there any issues with having one return inline and one at 90 degrees if he puts a dampaner on the inline one?

[TwincamDave]

Should be fine, probly won't need the damper.

[wahoo]

Agree with twincam, I'd leave damper out. Should be fine.

[SandShark]

I'd have him install at least a 14" flex. That'll put you right around 2000 CFM of return. Of course, that doesn't factor the restriction of the return air grills or the duct friction loss.