Return Air Grille Size...?

ssporty21228 · 08-15-2008, 03:32 PM

I have a 1636 sg. ft. home with a return grille that's 21" x 26"...there's only one and it's centrally located in my home. My question is this...is the size of the return grille sufficient to cool my house properly...?

And if not, what size should my return grille be...?

Thanks in advance for any help.

geo fan · 08-15-2008, 07:01 PM

2 seperate 14/30 connected with 14 round to a plenum. a single return would be huge and ugly . supply would start at 18 round , obviously these numbers are going to change with increased restriction or use of rectangle duct.

8 Ball · 08-15-2008, 07:12 PM

What size is your AC unit, if its 4 ton, you would need two of these.

What size is the return air duct, at the furnace or airhandler? If your ductwork is slightly smaller than the diffuser size, you would have to open up another wall pocket, put a crosspiece at the top of the opening, cut out the bottom plate and connect it to the existing duct. If you are on a slab, do the same thing, only at the top plate. If you want to mount it in the ceiling, its a little different, but you could then use the duct Geo is talking about.

Keep in mind, the size of the diffuser is important, but the size of the duct, volume of air and the static pressure all must be sized to acomodate the other. If the diffuser is on a side wall, it could be 6ft tall and 32in wide, but generaly its only going to be 31/2in deep , and only so much air can pass through that opening. If the main return duct is not sized for a four ton unit, 1600 cfm, it doesnt matter how many openings you have, its not going to work properly.

What size are the supply and return ducts (mains) and what size are the 9 supply branches.

Everybody get your ductilator ready...

8 Ball · 08-16-2008, 06:06 AM

Check and verify that the blower is going to high speed when you are calling for cooling, and please post the air handler model number. How old is your home?

You could save a lot of time if you can locate a balometer.

Thanks.

ssporty21228 · 08-17-2008, 11:00 PM

Quote:

Originally Posted by 8 Ball

Check and verify that the blower is going to high speed when you are calling for cooling, and please post the air handler model number. How old is your home?

You could save a lot of time if you can locate a balometer.

Thanks.

How do you check to see of the blower is going to high speed...?

This is the number I got off my trane furnace...tu080a948k0...mo21j5jig.

And the house is 27 yrs. old.

I apprciate your reponses.