Air returns in wall chases

What do you guys say when you see an air return has been formed partially from a wall chase (sheetrock wall cavity)?

They’ve been doing for years. Floor joist chases are common too.

Nothing. Why?

I see them often in older homes where they use the floor joists.(usually sheet metal) attached from joist to joist.
Not sure how this would effect an exterior wall however or the insulation install if using space between studs.

I comment if the void goes into the wall cavity to seal , if not seal it will draw air from the wall when the filter is dirty . The compartment should be sealed to draw all air through the return

Is the duct under negative pressure? Is there a possibility that the air being drawn into the duct/plenum comes from voids at baseboards, other trim areas, crawl spaces, etc. that bypasses the air filter?

Wayne gets it.

LOL thanks , I thought everyone would comment .

In the code I don’t see anything that prohibits it, by the way.

How does it bypass the air filter? It’s on the other end of the plenum at the air handler matter how you slice it.

Wayne apparently doesn’t get it.:roll:

Nah,who would argue with logic…wheres Mike?:wink:


See post above yours.:wink:

Mike Holmes writes it up!


Tell us more.

My issue would be the dirt and debris from lack of a smooth solid surface.

Picture the area beneath a staircase that is often used as a bathroom or closet is used instead as a part of the air return system. The filter in wall leads directly into this cavity. Could air get sucked in from the wood stair steps? At baseboards? From the crawl space? Yes I say. It would therefore bypass the filter.

BTW i do , it is you that has not grasped air flow. not all air filters are at the air handler Plenum . you do live a sheltered life don’t you:shock:

We don’t use filters in wall returns in this area.

Filters are in or next to the furnace.

I do see foam wall filters occasionally on cold air returns and they are always dirty but they are in addition to the filter at the furnace…

Guess where all that dust goes if you don’t have a filter on the entrance of the return air?