PVC Stubs In Plenum

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Bill Davis

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McDonough, GA
Hey Fellows,
I have noticed in many retail installations. The stock area is open to the deck with HVAC units supply ducted only. I notice time after time the conduits emerging from the slab are PVC from finished floor to the bottom of the panel. Is there an exception for this area? I would think these conduits should be steel. The last time i noticed this was in an auto parts store where the sales area was ducted above a drop ceiling and the parts area is open to the deck with only a header wall separating the two areas.
Thanks for your time,
Bill Davis
 
Which do you think is going to release more toxic fumes in a fire?

A few sticks of exposed PVC?

Or all the merchandise in an auto parts store? Think of plastics containers....lots of them. ;)

There is no code issue here.
 
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Bill Davis said:
The stock area is open to the deck with HVAC units supply ducted only.
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Does a stock room fit the definition of plenum?

Plenum. A compartment or chamber to which one or more air ducts are connected and that forms part of the air distribution system.
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Thanks for confirming the obvious.

Thanks for confirming the obvious.

I appriciate the input and understand the logic. I just don't want to put myself out on a limb.
 
Thanks for confirming the obvious.

Thanks for confirming the obvious.

I appriciate the input and understand the logic. I just don't want to put myself out on a limb. However if facing an inspector who wants to make issue is there any other code exception. I believe the code section is 312.? OK never mind I get it there are specific definitions in the hand book relating to the subject. sorry to bother.
 
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yeah! 300.22(b)

yeah! 300.22(b)

:confused: I guess I'm having trouble with the definition of plenum. I have had inspectors in the pass argue. Since the return air is not ducted, the area of the room open to the deck essentially is the return plenum and should be treated that way. No non plenum cables tie-wrap etc.
 
That would be correct. If all you have is return air grills in the room, then the area above the ceiling is being used as a plenum. I think in the situation that you are looking at, that the area might only be supplied by a swamp cooler which would be 100% fresh air and not require a return.

Here in CA it would be very hard to meet the insulation requirements and cool a warehouse with A/C.

Our mech inspector isn't here right now, but I also wouldn't see this any different than undercutting a door to get your return air and you can still plug in your computers and what not with out it having to be plenum rated cord.

If you considered the area a return air plenum then you probably wouldn't be able to stock some of the product in that area either.

Hope I'm explaining this alright.
 
John, Bill,

Am I missing something? Looks pretty clear to me.

(C) Other Space Used for Environmental Air. This section applies to space used for environmental air-handling purposes other than ducts and plenums as specified in 300.22(A) and (B). It does not include habitable rooms or areas of buildings, the prime purpose of which is not air handling.
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Chris,

No, you are probably correct, I was answering his question without pulling out my code book, and, I didn't really read the question very well the first time and misunderstood it.:rolleyes: I agree that the area would not be considered a plenum or treated as such.
 
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