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ajlewis1 08-13-2011 03:58 PM

Adding Return Air Duct in Master Bedroom

I had such great feedback last time I am looking for some more feedback.

I want to add a return air duct to my room.

The Return Air Size Grille I have (spare from another project) is 12x24.

Currently I have a two return air ducts in the house.

One that is at the top of the stairs which is 20x25 and the one downstairs which is 16x20.

My house is only 1200 sq ft.

My bedroom is upstairs, and like I said if the door is closed then their is no air that can get to circulate into our bedroom.

I am concerned about static pressure issue if I add the return.

To give some additional details.

I will want to use 10" duct for the 12x24 duct and the run would only be about 8 feet long in the attic.

The model numbers on the a/c in the attic are as follows:


Yes I know the A/C is old, but hey it still runs.

Look forward to the feedback


Jackofall1 08-13-2011 04:17 PM

More area less pressure drop, it's really that simple. The furnace fan will only push/pull so much air, the more area that air has to move in the less pressure drop there will be.

The problem may end up being that air will travel the path of least resistance, so if the resistance in the RA ducting you are adding to your bedroom is greater than the other (2) not as much air will move through your added RA register.

To counter that you can add restriction to either both or one or the other of the existing RA's. This will determine you OA balance and if you add too much restriction you may increase the static drop, but this is not likely.


beenthere 08-13-2011 04:41 PM

When you close your bedroom door, the air will travel back through the new return. So no problem with what you want to do. How many supplies in that room. It may look a little strange with the large of a return, depending on how big your bedroom is.

pete0403 08-13-2011 06:19 PM

Just from a different perspective, what if you just installed a vent in the bottom of your door? Positive pressure from the supply would force air out of the vent and not backup the supply allowing the air to circulate.

Doc Holliday 08-13-2011 07:14 PM

I'm adding two returns, one 12 x 12 fed by a 10" duct in the small master bedroom and one 14 x 20 fed by a 12" duct in the vaulted ceiling of the living room, tomorrow for a customer. Both are in attics/ceilings. The system only has one 20 x 20 on the lower wall of the hallway to the bedrooms currently and with the doors closed the rooms are staying hotter than the open areas.

I am in no way worried about static pressure drop. The more return the better. You can mess up only by restricting the supply air side of the system, or by giving too much away. The return side can mess the system up (air flow wise, static pressure) if there is too little of it, but that is neither the case for yourself or for me, just pulling heat and circulating the stagnant air is all.

I'm expecting great results as is the case every time I add a return.

Pics supplied tomorrow afternoon.

beenthere 08-13-2011 07:25 PM


Originally Posted by pete0403 (Post 706605)
Just from a different perspective, what if you just installed a vent in the bottom of your door? Positive pressure from the supply would force air out of the vent and not backup the supply allowing the air to circulate.

As long as he doesn't want any privacy, a grille in the door that transmits sound in both directions is ok.

SAMCRO 08-13-2011 09:19 PM

Is the bedroom Wall to wall carpet?

usually the door is under cut enough to allow for return air...(central return)

add a 5 or 6" supply w/ damper & under cut the door to your liking.:yes:

I think It would work better and look better....just a thought.

Master of Cold 08-13-2011 09:24 PM

You can also put in a grill in the bedroom, and one in the hallway, connect those with flexible duct. Transmits air, but not sound.

ajlewis1 08-14-2011 10:20 AM

Room has carpet
Thank you all for the great replies.

To answer some of the questions. The room is 17x20 and I have carpet in the room, and there is some space between the carpet and the door.

The door vents are an interesting idea but there is no way the lady of the house would ever let me put those in.


Doc Holliday 08-14-2011 04:26 PM

The 12 x 12 in the bedroom. Note how the return is right under the unit so I lengthened the run to loop out and come back for noise reduction reasons.

Doc Holliday 08-14-2011 04:33 PM

And the return in the vaulted ceiling. Prep work first.

The spot.

Cut and level.

Framing it in.

Done deal.

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