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#154161 - 06/28/04 10:56 PM return air plenum -entire floor cavity?
sparkystudent Offline

Registered: 04/06/04
Posts: 43
Loc: Staples, MN. USA
Residential jobsite using open web floor trusses between the upstairs floor and the downstairs ceiling. the EC arrived and found no HVAC ducting installed were told by HO/GC to go ahead and wire the home. after wiring the residence and installing 30 + recessed cans and recessed flourescent fixtures and pulling all home runs and LVcontrolls and central vac lines in the truss space hvac shows up and install all of the heat supply runs in ductwork in same area. the return plenum is intended to be all of the open area in this same cavity. no panning of any kind.return air grates are cut in up stairs and the boots just stub down into the floor/ceiling cavity. down stairs some cold air returns are cut into the ceiling( will be 5/8 sheet rock when finished) some are panned off between the wall studs but feed into the open ceiling cavity.all wiring done prior to their start of the return ductwork. AHJ has been called, awaiting his decision. question is has anyone else seen this, if so what was the AHJ decision. none of thewire or fixtures are rated for plenum or Air tite . what are your thoughts on this style of return air plenum?

[This message has been edited by sparkystudent (edited 06-29-2004).]

Building Codes & Related References
#154162 - 06/28/04 11:57 PM Re: return air plenum -entire floor cavity?
Ryan_J Offline

Registered: 08/19/03
Posts: 1355
Loc: West Jordan, Utah, USA
I have seen this one time before on a house that I was inspecting and I shot it down for the reasons you give. In addition to the items you mention, you also cannot have gas piping in a residential plenum, so if there is any gas there they won't be able to do it.
Ryan Jackson,
Salt Lake City

#154163 - 06/29/04 02:22 PM Re: return air plenum -entire floor cavity?
earlydean Offline

Registered: 12/22/03
Posts: 749
Loc: Griswold, CT, USA
What is on the plans????? Either the HVAC contractor or the electrical contractor will have to eat this one. Electrical contractors need to check with the HVAC plans before bidding the job!!!!!

#154164 - 06/29/04 02:57 PM Re: return air plenum -entire floor cavity?
DougW Offline

Registered: 06/08/03
Posts: 1083
Loc: North Chicago, IL
Oh, this is gonna be ugly...

#154165 - 06/29/04 06:32 PM Re: return air plenum -entire floor cavity?
hbiss Offline

Registered: 12/16/03
Posts: 893
Loc: Hawthorne, NY USA
What is on the plans?????

Probably nothing, this is residential. Around here, unless this is a very high end house, there is usually no mechanical plan.

Unless there was a way the EC could have known or even suspected that this was going to be done, I would say that because the HVAC guys got there after the EC it is their responsibility, especially if they designed it that way.


#154166 - 06/30/04 07:39 AM Re: return air plenum -entire floor cavity?
earlydean Offline

Registered: 12/22/03
Posts: 749
Loc: Griswold, CT, USA
The only winners are the lawyers, again.

My two cents: the HVAC contractor pulled a fast one. He should install return ducts.

#154167 - 06/30/04 07:49 AM Re: return air plenum -entire floor cavity?
Roger Offline

Registered: 05/18/02
Posts: 1779
Loc: N.C.
I agree with the others in the HVAC contractor being the guilty party here.

This contractor would be aware of the code issues too, and in the least should have red flagged it before installing his work.

Out of curriosity, who supplied the fixtures?


#154168 - 06/30/04 07:57 AM Re: return air plenum -entire floor cavity?
ElectricAL Offline

Registered: 10/10/01
Posts: 615
Loc: Minneapolis, MN USA
Hopefully common sense will prevail before any lawyers are inserted into the process. With all the cable and recessed fixtures in place at the time of HVAC roughin, the HVAC master should have been able to evaluate the situation and install accordingly, or at least, call the GC and start a change order for the "increased cost of ducting the return".

I'll just bet that the HVAC master stayed in the shop and sent out his lowest priced installer to handle the "simple new construction job", and that the installer just didn't give it any thought. Well. . .other than "hurry up and get out of here."
Al Hildenbrand


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