Return duct takeoff placement question

giantsean

Hi.. I am adding a return duct to an area which does not have one (not a bathroom or kitchen) which should solve some balance issues (I had a pro spec it out, now I'm just doing it). Since the ductwork has to take a few turns I'm using flex and weaving it through where it needs to travel.

My question is on attaching it to the return trunk, which is near the return plenum. The flex will be coming from a joist bay above. I was planning to use a square directional takeoff but not sure about the ideal placement for it. I figure I have three choices (as on pic)

1) top of duct - tough install (very tight) least length of travel and curving but not sure if top is ideal for airflow and whether it's too close to plenum / duct end

2) side of duct close to plenum - easier to install, less travel, but maybe too close to end

3) side farther away from end - longer travel and change of direction

Maybe I am overthinking it and it will make no difference on a return, but as the system is choked enough on the return side (which I am trying to remedy) I definitely do not want to make it worse. Thanks for any advice!

As an aside, is this takeoff bent wrong or is the front edge supposed to be offset like this? You'd think it would be flush. Thanks again!

mattmia2

Looks like they missed when they welded it together. You can take the drive cleats off the sections of the return and disassemble some of it for better access.

EBEBRATT-Ed

If you have room I would go in #1 (top) You may want to use a metal elbow or a top take off that goes to round so you don't pinch the flex too much. If not go in #2 or#3.

Even if your connection is less than ideal and if the existing return is too small if your return is choked it will be better than it is now.

JUGHNE

If you have room in that area, you could put the takeoff right on the side of the return air drop up near the top.

I would then use hard pipe/90,s up to your flex duct. Form the elbows into 45's if possible.

giantsean

Do you mean something like this? (red would be two metal 90's turned at 45, blue would be the direction of the flex.

What would be the best way to support that?

JUGHNE

Yes, support with hole strap around the elbows and then screwed into the insulated metal duct above it.

Screws thru hole strap into elbows also to keep strap from walking.

Maybe add a screw or two to the existing hanger on insulated duct.