Ducting Systems and Air Ventilation - Installing new return air grill

Hi,

I have an attic central air system with a ceiling mounted return air grill. I would like to change the return air grill size (due to a conflict with some remodeling) and I need to verify the parts required since I probably have to get these online. The sales guy verified my part list but I don't fully trust him.

The filter area will remain the same as the current filter. My central air system has a 16" flex duct for the return air. I will have to move one 2"x4" brace in the attic a few inches to accomodate the new return air box. Position of air box will only move a few inches (closer to ca unit).

1. Hart & Cooley 673 18" x 24" return air grill.

2. Sherer manufacturing 18"x24" R6 return air box

3. Sherer manufacturing 616-16 Ductboard tab collar 16"


Will these parts all work together and do I need to fabricate any other parts (I have very limited fab capability)?

It's not clear to me how the tab collar attaches to the air box. Do you cut a hole in the air box or do you have to attach sheet metal with a hole to the air box?

Also, I believe mastic is used to seal the tab collar to the box.

The Sherer website has very little info on these products.

http://www.sherermfg.com/Return-Air%20Boxes.pdf

http://www.sherermfg.com/Tab%20Collar-one.pdf


Thanks for any info.

**First of all DO NOT GO DOWN IN SIZE if possible go up to the next size unless the box you have now is insulated .**

These parts will work (BUT i see no need for a scoop thats used in supply not return) Your flex should still reach , if it has a 90 degree elbow reuse it.
That looks like a ductboard collar which will work with that box since it should have 2 inch insulation in it , but 1 inch will get you by.

You will have to do this below you are correct , lay the straight collar in the center use a black permanent marker mark the outside of the tabbed side , then lay it aside , then lay a flathead screw drive at a 45 angle (holding box between legs unless installed ) strike with a hammer at flathead end to get a hole started hold screwdriver straight up strike at bottom get you a long slice in it then go to work with the snipes cutting out side edge of black mark , cut out insulation with knife , stick collar ,(may have to trim a lil more to get a good fit ) push collar tru bend tabs back on insulation and mastic around top of collar , let dry , you have it pull the liner of the flex duct tape it and zip tie it , then pull insulation and outer liner over it , all the way to box , zip tie it , seal with mastic at all joints

Its not clear to me how the tab collar attaches to the air box. Do you cut a hole in the air box or do you have to attach sheet metal with a hole to the air box?


And I would get a gallon of mastic to seal lt and use the rest to go over any other joints . It will wash off your hand but not your clothes

Hope this helps.

Thanks a lot Grim,

Parts arrive today so your post is just in time.

The vendor only sold the mastic in large tubs so I did not order any.

Can the correct mastic be found at the home centers?
I know it's sometimes used for tile installs but don't know if it's the same thing.

Thanks a lot Grim,

Parts arrive today so your post is just in time.

The vendor only sold the mastic in large tubs so I did not order any.

Can the correct mastic be found at the home centers?
I know it's sometimes used for tile installs but don't know if it's the same thing.

Maybe at lowes or home depot if not try noland supply they normally sell to public I dont think tile grout is same as sealing mastic really .