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-   -   Why aren't foundation wall duct openings wider?! (http://www.diychatroom.com/f19/why-arent-foundation-wall-duct-openings-wider-149552/)

joshoc 07-08-2012 10:24 AM

Why aren't foundation wall duct openings wider?!
 
1 Attachment(s)
Apparently the 32 inch wide opening in the cinder block foundation wall of our house is not wide enough for the supply and return air ducts.

The width of the supply and return OPENINGS on the HVAC UNIT, plus the space between the openings is significantly more than 32 inches.

I found out today that the flexible return air duct is about half blocked by protrusion of the foundation wall into its path, because the duct has to veer over so much to attach to the HVAC unit after it passes through the wall.

Why don't they build wider openings in the foundation wall for the air ducts? The openings in the HVAC unit where the ducts attach are not directly side by side, they have space between them, making the unit much wider than the opening in the foundation wall.

The picture I attached is standing in the grass looking into the return duct with the left side panel of the unit removed. The blocked part is solid cinder block - I cannot push the duct open any more than it is.

Thanks,
Josh O.
Nashville, TN

hand drive 07-08-2012 10:29 AM

apparently there was a discrepancy between the mason and the hvac guy while building the structure or the unit is placed to far to the left of the opening??

Minus08 07-08-2012 10:29 AM

Quote:

Originally Posted by joshoc (Post 960639)
The picture I attached is standing in the grass looking into the return duct with the left side panel of the unit removed. The blocked part is solid cinder block - I cannot push the duct open any more than it is.

I do not see and cinder block wall in the photo. Whats folded in on the left of the photo looks like the facing of the duct wrap

joshoc 07-08-2012 10:35 AM

hand drive, I think if the unit was to be moved to the right then the SUPPLY duct would become blocked in the same way.

CopperClad 07-08-2012 10:37 AM

I'm not a HVAC guy... but is it common that you guys put the supply and return through foundation walls? Must be a TN thing..:eek:

joshoc 07-08-2012 10:37 AM

Minus08, the cinder blocks are pushing into the path of the duct, causing the big blockage. You can't see them because the duct is covering them.

Bonzai 07-08-2012 10:38 AM

Having trouble understanding what the question is. Are you asking us why the hole in the foundation wall for the duct shown in the photo is not better aligned with the HVAC unit? If that is the question then you would really need to ask whoever installed the HVAC system. Most likely a bit of a screw up between trades unless there is something structural or otherwise that prevents them being aligned correctly.

Minus08 07-08-2012 10:40 AM

Quote:

Originally Posted by Bonzai (Post 960655)
Having trouble understanding what the question is. Are you asking us why the hole in the foundation wall for the duct shown in the photo is not better aligned with the HVAC unit? If that is the question then you would really need to ask whoever installed the HVAC system. Most likely a bit of a screw up between trades unless there is something structural or otherwise that prevents them being aligned correctly.


I think the poster is just venting.

Minus08 07-08-2012 10:41 AM

Quote:

Originally Posted by joshoc (Post 960653)
Minus08, the cinder blocks are pushing into the path of the duct, causing the big blockage. You can't see them because the duct is covering them.


Gotcha. Can you put up a photo from the inside?

Bonzai 07-08-2012 10:41 AM

Quote:

Originally Posted by Minus08

I think the poster is just venting.

No pun intended eh lol

joshoc 07-08-2012 10:43 AM

Bonzai, I'm asking why wasn't the hole in the foundation wall built wider by the home builder, because the hole is not wide enough for the unit no matter how the unit is placed. 32 inches wide is not wide enough.

hand drive 07-08-2012 10:48 AM

Quote:

Originally Posted by joshoc (Post 960664)
Bonzai, I'm asking why wasn't the hole in the foundation wall built wider by the home builder, because the hole is not wide enough for the unit no matter how the unit is placed. 32 inches wide is not wide enough.


there is a certain amount of flex/decrease allowed in flex ducting but what you have looks to be to much. the building plans might have called for a smaller air system intitially and ended up with a larger one and the mason was long gone by then.

I'm curious, under the house,in the floor framing how did they structurally span the weight load over top and across of the 32" opening? are there visual added double house bands,joist hangers, etc...? it could be framed to support a larger opening in the block wall... maybe the framers got it right?

Bonzai 07-08-2012 10:51 AM

Quote:

Originally Posted by joshoc
Bonzai, I'm asking why wasn't the hole in the foundation wall built wider by the home builder, because the hole is not wide enough for the unit no matter how the unit is placed. 32 inches wide is not wide enough.

I think all we can really do is speculate but ultimately the home builder is the only one that really knows why they did something the way they did.

Evstarr 07-08-2012 11:05 AM

Quote:

Originally Posted by Minus08

I think the poster is just venting.

Ha ha. Venting would be a different thread!

Edit: aww too late!

joshoc 07-08-2012 04:05 PM

Pictures and basic question
 
3 Attachment(s)
Here are two pics from inside the crawlspace and one from the outside.

The return duct (on the right if you are viewing the photo from inside the crawlspace) has to make a hard shift to the right immediately after it passes through the cinder block wall in order to connect to the unit outside, causing its airflow to be half blocked. And maybe the supply duct on the left is having to shift hard to the left as well, I don't know.

But my question basically is: shouldn't there be a code requirement that the opening in the cinder block wall be a minimum of 40 inches wide or something? Clearly 32 inches is not wide enough for this 2 ton unit.

And 2 tons is not even that big.



Here are the pics.


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