[mattorrell]

I am renovating a closet that contains a Skypak RGAC 2 ton natural gas fired heating and a/c unit, including sound proofing with 2 layers of sheet rock and mass loaded vinyl. The original return ducting was not done properly several years ago (i.e., return air drawn from inside the closet) and I am setting up ducting so the return air draws from outside the closet.

I have a 12 x 36 titus aero-blade filter grill and I am trying to figure out the best was to mount it in the wall with a boot that would transition to 12" flex duct. The filter grill has holes on the side for attachment to framing. Interested in getting some perspectives on how this might be accomplished in terms of an approach to framing, boot construction and installation (e.g., duct board, ceiling box, etc).

I am attaching some pictures of the filter grill.

Thank you very much for your help!!

 

[TarheelTerp]

I have a 12 x 36 titus aero-blade filter grill and I am trying to figure out the best was to mount it in the wall with a boot that would transition to (the furnace)...

Do you know anyone in the sheet metal business?

By the end of the month you will.
Most are nice guys.

 

[mattorrell]

I have been working with someone to build a ceiling box with 12" collar. The idea is that the ceiling box will push through hole in the wall and flange of ceiling box will sit on face of sheetrock. Grill will insert into ceiling box and and then screw into wood framing from the side.

1) The metal shop is having a tough time making this
2) Wanted to make sure my idea is doable

Thanks for the feedback.

 

[beenthere]

12 inch flex is too small for 2 tons.

12X36 grille is barely borderline.

 

[mattorrell]

Thanks. Would 14" do the trick?

 

[beenthere]

Thanks. Would 14" do the trick?

14" is ok. I generally use 16" flex for a 2 ton return. Keeps it quieter. But your small grille will still be loud.

 

[mattorrell]

Thanks. I'll switch to a bigger grill. What size would you suggest for use with the 14" flex. Great if you could suggest a brand also - going in a bedroom so want to keep it quiet.

 

[beenthere]

Hart&Cooley 672 return air grille. 14X36. Should give you a velocity just under 300 FPM. However, the 14" flex will have a velocity of over 750 FPM, which can make some sound. 16" flex velocity would be just under 580 FPM, which is quieter.

 

[mattorrell]

Thank you so much for all of your help. I would go with your 16" flex suggestion but my width is limited to about 14.5" by a wall. I have attached a picture.

On that note, what kind of duct fittings/duct work do you suggest to make the transition (in a tight width of about 14.5") from the HVAC unit where you see the filter (will be relocated to a filter grille) to the 14" flex. The flex (or any other ductwork) would need to come out, down, and to the right where it will hook into a boot/grille in the to be built wall. I doubt a 14" adjustable 90 deg. elbow can make that downward turn in 14.5" of space.

Any ideas are appreciated!!

Thanks.

 

[TarheelTerp]

On that note, what kind of duct fittings/duct work do you suggest to make the transition (in a tight width of about 14.5")...
Any ideas are appreciated!!

OK.
1) Tear out that unfinished closet framing.
2) Sort out what's needed for the mechanical aspect.
3) Enclose whatever that may be... after it is in place.

 

[beenthere]

I don't see enough room in that closet for a 14 inch flex to make a 90 degree turn.

 

[mattorrell]

Yes, it's a tight fit. Would 12" (or 13" for that matter) round sheet metal duct be sufficient for 800 CFM return instead of 14" flex duct?

(Would be 14" x 36" filter grill, ~30" straight run of round sheet metal duct, 90 or 45 deg. sheet metal elbow, into something the shape of a stackhead boot connected to the HVAC unit.)

 

[beenthere]

As far as I know, 13" hard pipe isn't made. You would need to have it custom made. It would be ok for 800 CFM.