Transfer Grills above doors for return air?

[handyman5]

I live in S. Florida and want install transfer grills above the doors of our bedrooms to increase the return air flow back to the main return grill in the livingroom. Currently the doors are slightly cut on the bottom but I don't believe it provides the proper amount of return air.

I would like to know how these are typically installed.
I will be cutting a how in the sheetrock on each side of the wall above the door and will place about a 6"X12" grill on each side.

I need to know a few things:

If there is a stud which obstructs air flow; is it cut and braced horizontally or just left in place and ignored.

To keep air from flowing from the insides of the wall, should I frame it out with wood or just try to seal it off with pieces of duct board and foil tape?

Will I need a baffle between the grills to reduce noise and retain privacy between rooms? If so, can I buy these pre-made or is the an easy way to make them myself.

I have not seen a home yet with a return duct system in South florida; is this common practice?

Do you think adding the transfer grills is overkill and I should just undercut the doors more?

Thanks for all opinions and advice,
Doug

[bbk]

I think it's overkill on a residence.
Didn't do it to my house when I built it.

The header above the door should be sealed from the walls and attic already,just cut the sheetrock,leave the cripples alone .
You can just turn the grill "upside down" if you don't want to look into it at the 2x4. There's no kinda baffle that's gonna work in that space.

[Jim Davis]

Transfer grilles above doors is very intelligent. It is hard to push hot air under a door but it is cheap. Probably won't be any noisier than what comes under the door. Leave studs in place and frame opening in wall to keep out dirt and infiltration. Under cutting doors is cheap but not effective except for heating(maybe) but is standard practice.

[tpa-fl]

Jump-duct are the way to go... Transfer grills will get the airflow part right, but at the expense of noise & light transmission, not to mention they're ugly. I've seen some of the transfer grills with baffles before and they don't work. noise still goes right through them.

Jump ducts are rather easy to install, as you can fit them just about anywhere & can move them to accomodate joists/studs/etc. 2 diffuser boxes w/some flex duct and you're in business. If you have good attic access, run that flex back to the AC's return and do it the right way. Every newer (>'95) house I've seen has returns in the bedrooms, but I usually only see higher-end housing. Not sure what the large builders are doing... I'd assuming they're skipping it since it cuts into their bottom line.

[Mr Bill]

Originally posted by tpa-fl
Jump-duct are the way to go...

What if you have an upflow unit in a closet how do you install these "jump-ducts"

[tpa-fl]

Originally posted by mrbillpro

Originally posted by tpa-fl
Jump-duct are the way to go...

What if you have an upflow unit in a closet how do you install these "jump-ducts"

If you're installing it to the AC's return, then it becomes a return rather than a jump-duct that runs from the bedroom to the living room. The poster lives in S. Florida, so there's a 90% chance that the air handler's in the attic.