DIY Home Improvement, Remodeling & Repair Forum > Appliances > HVAC > Hvac Rectangular Stack Inside Wall


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Old 12-30-2016, 10:13 PM  
tk3000
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Default Hvac Rectangular Stack Inside Wall

Hello Folks,

Recently, I started fixing and assembling ductwork inside the wall for the hvac. Some of the ductwork was simply missing, so I had to assemble entire rectangular ductwork out of 3.25"x10"x3ft half sections rectangular stack duct, s cleats, drive cleats, rectangular head (where the end forced vented grill will be present), stack boot (connecting the upper end of the stack to the ductwork in the attic). I also acquire the proper tools: bending/folding tools, snippets, etc.

The following pics depicts the assembling stages:


(part of the rectangular stack connected to the stack head, stack head has a flange that could be used to screw it to the bottom plate of the wall)







(with connections made out of cleats and s-cleats, it is not a rigid structure, and was wondering if that is the way it is supposed to be?)

So, I was wondering if that is the right approach to fabricate these ductwork stacks. Should be cleat connections be taped with foil tape? Should the whole stack be wrapped in reflectix insulation?

thks!



Last edited by tk3000; 12-30-2016 at 10:27 PM.
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Old 12-30-2016, 10:17 PM  
tk3000
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Cont... (could only post so many images in one thread post)


(dry fitting on spot inside walls)

Last but not least, this is not a very rigid structure (the fabricate stack) to be rigidly erected inside the wall, and besides the flap present on the stack head at the bottom (which will be screwed to the bottom plate of the wall) there is nothing else supporting it; so, I was wondering what type of extra support -- if any -- should/could be added?

Also, whereon the upper boot connect to the ductwork in the attic above it seems that it just fits in there... should tape be added to better seal it (can not use sheet metal screws, not enough clearance)



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Old 12-31-2016, 09:38 AM  
Jeffh
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YOu can add self-tapping sheet metal screws to the s-cleats about 2" in from either end, keep in mind you are going through about 5 layers of tin. This will give the wall stack duct some added rigidity as short drive cleats dont stiffen it up much. Wouldnt hurt to add foil tape to the joints.
You can add strappings(or a long 16" drive cleat) across each stud on other side, and screw it to the ductwork as well. That will secure it a bit better in place.
Round connections should be fastened with at least 3 screws, but at least one would be nice. Taping it wont hurt afterwards.

Trim your drives down to a 1" fold over, you got like 2-3", makes it look shoddy.
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Old 12-31-2016, 01:07 PM  
beachguy005
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If that's a return air duct, they usually just use the studs and wallboard on both sides as the air plenum, and not actual duct work. If you are going to use it, when you attach it to the bottom you should raise it up high enough for baseboard trim to go under the grill.
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Old 12-31-2016, 03:29 PM  
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I think they sell a heavy guage strap that you would nail to the studs and then screw through into the duct to stiffen it . Is this a single story with duct in the attic ? I just used ceiling grills if that's the only reason your opening up the walls .

And the previous poster is right , looks a bit low . Figure your grill is going to have a 1" flange on it , what's the height of the baseboard?
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Old 01-01-2017, 05:50 PM  
tk3000
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Quote:
Originally Posted by beachguy005 View Post
If that's a return air duct, they usually just use the studs and wallboard on both sides as the air plenum, and not actual duct work. If you are going to use it, when you attach it to the bottom you should raise it up high enough for baseboard trim to go under the grill.
No, this is not an air duct return (I realize that they don't need an actual duct for returns). It is a force air duct.

By raising the stack at the bottom you mean maybe adding a piece of 2x4 to that segment of the bottom sill?

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Old 01-01-2017, 05:58 PM  
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Quote:
Originally Posted by buffalo View Post
I think they sell a heavy guage strap that you would nail to the studs and then screw through into the duct to stiffen it . Is this a single story with duct in the attic ? I just used ceiling grills if that's the only reason your opening up the walls .

And the previous poster is right , looks a bit low . Figure your grill is going to have a 1" flange on it , what's the height of the baseboard?
I will look into the heavy gauge straps, maybe once it screwed in place it will bee rigid enough.

No, that is not only reason: the drywall was damaged so I would have to replace part of it anyways, besides I am also doing some electrical work along the way (albeit at a very slow pace lately)

The previous stack (or what was remaining of it) had it head stack attached directly and square onto the bottom sill plate, that why I was planning to attach it directly there. Would a piece of 2x4 atop of the sill plate be enough to raise the stack?

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Old 01-01-2017, 06:31 PM  
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As far as height , what's the floor going to be ? Carpet / hardwood ect , and how deep will it be ? Figure your grill on the wall will be an inch lower than the square opening . How tall is your trim ? If it's to low you may be into the baseboard trim is all.

I tried searching the Web quick and couldn't locate the straps . Basically it's a 1" strip of metal , just a heavy guage like 18guage.

I personally like oval wall stack , easier than slip and drive .
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Old 01-01-2017, 09:32 PM  
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Quote:
Originally Posted by buffalo View Post
As far as height , what's the floor going to be ? Carpet / hardwood ect , and how deep will it be ? Figure your grill on the wall will be an inch lower than the square opening . How tall is your trim ? If it's to low you may be into the baseboard trim is all.

I tried searching the Web quick and couldn't locate the straps . Basically it's a 1" strip of metal , just a heavy guage like 18guage.

I personally like oval wall stack , easier than slip and drive .
Ovals are nice but every time I have had to work on them, I have had to get the boot made, nobody has a pattern for it..
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Old 01-01-2017, 09:36 PM  
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Fill the space between the studs and the boot at the bottom , screw the boot to it and you will have something to screw the grill to.

Just a flat piece of sheet metal long enough to reach both studs screw in place,

I like to lift them so the floor molding goes below.


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