• Welcome to the new and improved Building Code Forum. We appreciate you being here and hope that you are getting the information that you need concerning all codes of the building trades. This is a free forum to the public due to the generosity of the Sawhorses, Corporate Supporters and Supporters who have upgraded their accounts. If you would like to have improved access to the forum please upgrade to Sawhorse by first logging in then clicking here: Upgrades

Plumbing in Return Air Ducts

No matter, plastic not allowed in CA returns......unless it is somehow listed that it can be.

I've heard, but not seen the listing, that there is a sprinkler pipe that has been list for CA retursn. listed
 
Thanks Gregg, I new it wasn't allowed but couldn't find it in the plumbing code due to the answer being in the IMC.

Pc1
 
I agree it is not a plenum. My first ? would be has the design return capacity been changed, alter or reduced by the drainage pipe.

That would be assuming it is a drainage pipe! If it is an exhaust vent for a heater ???? what say you?

Last can not tell if there are cleanouts or connections associated with the pipe if it were DWV?
 
603.9 Joints, seams and connections.

All longitudinal and transverse joints, seams and connections in metallic and nonmetallic ducts shall be constructed as specified in SMACNA HVAC Duct Construction Standards—Metal and Flexible and SMACNA Fibrous Glass Duct Construction Standards or NAIMA Fibrous Glass Duct Construction Standards. All longitudinal and transverse joints, seams and connections shall be sealed in accordance with the International Energy Conservation Code.
 
mtlogcabin said:
It is not a plenum it is a duct. If it is a SFR then any material is allowed in a plenum. See exception #3 under 602.2.1.
Click to expand...
I started to go with duct at first glance, but when the picture is enhanced it appears to be a cavity between two floor joists that has a sheet of duct board caulked to the edges of the joists. This would then make it a plenum and not a duct if that is the case the wiring would violate NEC the wiring can run perpendicular to the long run.

300.22©

Exception: This section shall not apply to the joist or stud spaces of dwelling units where the wiring passes through such spaces perpendicular to the long dimension of such spaces.

IMC 602.2.1Exception #3 does exclude plenums in one and two family homes, but I think this is an oversight since the prohibited point is that materials meet ASTME 84 or UL 723 for smoke and flame 25/50. PVC does not meet these standards.

Without a clearer picture it is hard to tell the distance the pvc runs in the joist span so support would also be an issue.
 
California code reads different than what I have seen quoted here. CMC does not have section 602.2.1

California did not adopt the IRC mechanical sections. So I should have stayed out of this thread.

602.2 Combustibles Within Ducts or Plenums. Materials exposed within ducts or plenums shall be noncombustible or shall have a flame spread index not greater than twenty-five (25) and a smoke developed index not greater than fifty.

Exceptions:

(1) Return-air and outside-air ducts, plenums, or concealed spaces that serve a dwelling unit shall be permitted to be of combustible construction.
Click to expand...
The duct, plenum or concealed space can be of combustible construction. Anything not a part of the duct, plenum or concealed space and not one of the eleven exceptions shall have a flame spread index not greater than twenty-five(25) and a smoke developed index not greater than fifty.

I seldom find DWV pipes but I do find a lot of condensate pumps.

http://www.homedepot.com/p/LittleGIANT-Nextgen-115-Volt-Condensate-Removal-Pump-VCMX-20ULS/203464514#.UdCis-uxPcI
 
Last edited by a moderator:
Is this in a single family residence? If it is, the IRC would apply, not the IMC. IRC does not prohibit combustibles in joist return plenums, including pvc. The wires running parallel with airflow are prohibited by NEC, but any wires perpendicular to airflow are allowed.

If this is in an apartment building, then the IMC does apply and both the pvc and wires are prohibited. By IMC, the wires need to be either in a conduit or plenum rated regardless of their direction in relation to airflow. The IMC simply states all wiring exposed in a plenum needs to be plenum rated.
 
That's the way I would call it (as long as the pvc is plumbing and not a vent for a High efficiency furnace or water heater). The other thing i might question is how the ductboard? is attached to the floor joists. I don't think I would accept caulk as the means of securing it in place. The foil facing should extend onto the bottom edge of the joists at least an inch and be stapled in place evry few inches.
 
klarenbeek: The photo is not a straight forward as one may think. We see the pipe going in? or is it coming out? It is obvious that it is a return, but does the pipe turn up and drain fixtures for other floors. NII!
 
Would the ductboard have to be fire rated if thats the garage ceiling or house/garage wall? It has red tape?

pc1
 
RJJ said:
klarenbeek: The photo is not a straight forward as one may think. We see the pipe going in? or is it coming out? It is obvious that it is a return, but does the pipe turn up and drain fixtures for other floors. NII!
Click to expand...
Hey now thats not fair trying to trick an inspector! I'm not used to that. :grin:

You're absolutely right. If its just passing through, its ok. If the pipe turns up to fixtures above, at a minimum the holes through the floor would need to be sealed ase well, depending on whats above.

I think the tape is UL181A
 
You must log in or register to reply here.
Top