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When is it a plenum?

steveray

steveray

SAWHORSE
Joined
Nov 25, 2009
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11,751
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West of the river CT
IMC plenums……How enclosed does an area need to be to qualify? Wish I could do a drawing….Picture retail with “back of house” demising wall….Bathrooms and breakrooms are in the back of house. They are enclosed on 3 sides with walls (to the roof deck) the are open to the atmosphere and vision of the stock room for maybe 20% of the above ceiling space perimeter? In this case about 20' wide by 15' high communication/ exposed hole to the back of house storage area If that makes sense?

PLENUM. An enclosed portion of the building structure, other than an occupiable space being conditioned, that is designed to allow air movement, and thereby serve as part of an air distribution system.

I don't have a huge concern either way, kind of on the fence, just sucks for everyone that I went out for an above ceiling and saw all of the PVC......And the "plenum"....Thoughts?
 
The way the HVAC system is set up, is it pulling air through that space? either through ceiling transfer grills where the air gets pulled through, above the ceiling, then out to the main open space, or from the open space to a return duct above that ceiling?
 
Good question...and I like the thought process....I may have to take a second look.....I told the contractor to consult the designer for an answer while I looked into it, but maybe I can swing back by and rule it out one way or the other....Guessing the return is outside of the area with the ceiling, not above it.....
 
klarenbeek said:
The way the HVAC system is set up, is it pulling air through that space? either through ceiling transfer grills where the air gets pulled through, above the ceiling, then out to the main open space, or from the open space to a return duct above that ceiling?
Click to expand...
I agree with your post
May I suggest, to make really clear, that the space above the ceiling is being used as a return DUCT. With, perhaps egg crate or real grills in a hung / acoustical ceiling, which is typical for the term Plenum that "communicates with the intake of an air handler
 
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