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Heating & Air Conditioning

Cold Air Return duct question - what is this? (pics)

15 years ago

After a major renovation last year that relocated much of our duct work, the HVAC contractors did a less than stellar job. As I go through and right the wrongs (unconnected supply lines, unnecessary elbows and splices, shoddy assembly...), I've noticed a few things about the cold air return.

The main cold air return line runs the length of my long bungalow. One of the returns is in an upstairs hallway more or less directly above the return line. What has me puzzled is why the contractors boxed in a LARGE section of joists as part of this return (see the photos)?

The first photo shows the boxed in section. The cold air return comes through the floor directly above the I-beam. The second photo is looking over the main cold air return line into the boxed section (note that the boxed section was already "boxed" by a piece of blocking!), and you can see the cutout of the floor above for the return.

Is there an explanation for this?

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Also, the actual sheetmetal cutouts in the return trunk line (barely visible at the bottom of the 2nd photo) that draw from this cold air return aren't huge... they are a pair of standard supply line boot size rectangular cutouts (~5x6?). Is that adequate, or should they be larger?

Thanks for the help; hope my explanation is clear!

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Comments (6)

Tinmantu
15 years ago
The square inch opening in the ductwork should easily supply the small opening through the floor that you have. Not sure why they added the extra return panning, unless someone forgot to cut an opening in another room or were getting paid by the square foot of metal used.
Tinmantu
15 years ago
just looked at the pic of a single joist pocket on the second picture, but 1st picture shows 2 pockets panned...I'll step back from further comments for now.
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fitzski
Original Author
15 years ago
Thanks for the reply, tinman.

Yes, there are two joist pockets, because the CA duct in the floor above straddles the middle joist, and there are two openings in the ductwork (one for each joist pocket).

I'm leaning towards tidying this up - I can't imagine it's helping the efficiency at all. Only thing I could think was if for some reason there needed to be a mixing/balancing of air temperature from upstairs with downstairs before reaching the furnace - but that seems a stretch.
fitzski
Original Author
15 years ago
Any other thoughts before I tear this apart and tidy things up? Will I be messing up the system balance somehow?
Tinmantu
15 years ago
As long as you still have the pocket enclosed to the return it won't do anything to the system balance..as far as tidying things up, the wires and exposed pipe are more obvious eyesores that every unfinished basement has. I'd just make sure that the duct space between the supply and return to the joist panning is properly sealed and find something else to fix around the house. :)
fitzski
Original Author
15 years ago
LOL - yeah, there's certainly plenty to do!!

It's done now, though - a bit cleaner, and a whole lot more efficient (now that it's properly sealed, and some other gaping holes fixed).

Thanks for the replies.

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