Replacing 90 degree turn in supply duct that also contains air register

[robert_oddy]

I am remodeling my bathroom and would like to make this bulkhead as small as possible. Is it OK to get this bend swapped with flex duct or something along those lines? Would anyone have good ideas on how to minimize the space needed to connect these ducts?

Thanks in advance.

[VTP99]

Looks like that goes up from there.

[robert_oddy]

Yes it goes up and out to the rest of the house.

[VTP99]

What's the dimensions of that vertical duct ?

[robert_oddy]

It is 9" x 12" (the horizontal part from air handler is 9" x 8")

[BNME8EZ]

It looks like there are 2 elbows there, one turning up the other turning toward the camera maybe between the joist.

I don't see how you are going to improve that much except making the register opening smaller and having turning vanes put in the elbows. As to size you are kinda stuck.

[kdean1]

Use of flex will make it worse. Flex is not for turns.

[VTP99]

It is 9" x 12" (the horizontal part from air handler is 9" x 8")

That's odd that the duct would increase moving down stream.

[VTP99]

Is the air handler above or below this floor ?

[robert_oddy]

There's a 90 deg elbow that goes up into the ceiling, then from there it Ts out, one way going towards the camera and the other going away from camera. That arrow pointing up that says "to rest of house" really should be pointing at the camera.

I was thinking of getting a 90 deg round elbow installed instead but that probably wouldn't save any room. Would it be better just to get turning vanes installed?

As for the register, I was planning on just closing it off.

[robert_oddy]

The air handler is actually on the same floor to the right on other side of wall (this is the basement). We are maybe about 2 ft away from it in this picture. The duct does increase in size, maybe because it Ts off in the ceiling but I am just guessing.

[BNME8EZ]

So you have 1- 9x8 feeding 2- 9x12. What part of nowhere does that work?

Is there any way to increase the 9x8 either wider or deeper?

[VTP99]

Wow it must really blast out of that bathroom vent.
I think you're stuck with what you've got other then lowering that area.

[robert_oddy]

So you have 1- 9x8 feeding 2- 9x12. What part of nowhere does that work?

Is there any way to increase the 9x8 either wider or deeper?

I don't think there is without a lot of work. That duct from the right comes straight off the air handler. The supply duct comes up from unit then Ts out to opposite sides of the house. The incoming duct in picture is one side of the T.

So from the sounds of it I am pretty much stuck with this bend.

[kdean1]

This is an instance of sacrificing performance for space. Air does not like to change shape or direction. There are good and bad fittings as far as air flow. The ones in the pictures are bad. Air flow is not like an extension cord which can be plugged in and then travel in circles to the other end.

Turning vanes will help. It remains to be seen how much.

[robert_oddy]

This is an instance of sacrificing performance for space. Air does not like to change shape or direction. There are good and bad fittings as far as air flow. The ones in the pictures are bad. Air flow is not like an extension cord which can be plugged in and then travel in circles to the other end.

Turning vanes will help. It remains to be seen how much.

Would it even be worthwhile to get the upward bend replaced with a 90 deg round elbow? I think there would be some space saved and better airflow, but not sure if the time and cost is worth it.

[kdean1]

Only if a square to round transition is built to the elbow. Putting a round fitting into the end of a square trunk creates a lot of turbulence.
Plus an elbow will have a radius on the inside of the turn so it will take up more room. A curved inner radius is good for air flow. A sharp 90° inside turn is bad for air flow.