Zero Clearance Install - Chase Questions

[Gazerbeam]

I'm finally getting around to installing my Quadrafire 7100fp into an existing exterior chase that originally had a gas fireplace there. I'm planning on using the Duraplus chimeny pipe.

I have a couple questions.

My understanding is that even though this is an exterior chase that doesn't intersect the attic space, I still need to install a firestop and an attic insullation shield at 9' (ceiling height). It that true?

Is there any advantage in insulating the chase above and below the firestop or should I just do below?

I'm planning on using 5/8" basic drywall to cover the insulation inside the chase or would there be any advantage in using durarock instead?

Thanks!!

http://farm5.static.flickr.com/4150/4986393443_cec680b13d_b.jpg

 

[begreen]

Correct. Check page 14 of the manual: E. Construct the Chase. There is a diagram showing the firestop:

Building codes require false ceiling and ceiling firestops at each floor of the chase or every 10 ft (3048 mm) of clear space to control spread of fire.

Looks like insulating under the firestop is fine, with a layer of insulation on top of the false ceiling to retain heat in the lower cavity. Sheetrock is ok, though not sure it is required. Keep clearances to combustibles to the pipe over 2"

 

[Gazerbeam]

Ok, thanks for the reply. I figured that was right, but it's always nice to get confirmation from someone with more experience on the subject. My only other theory was that an open, insulated volume all the way up to the top of the chase would help improve potential draft issues. I'll add the firestop and build it up as show on the diagram in the manual.

 

[begreen]

I don't want to mislead here. The intention of the docs seem relatively clear to me, but I have no experience in this area beyond reading the manual. I have never installed a ZC fireplace.

 

[Gazerbeam]

No problem, I appreciate anyones input. That was my interpretation of the manual as well.

Another question I have is about making a modification to the framing of the chase. Right now, the combustion air intake interferes with a 2x4 stud. The 2x4 is a one piece, 15' long stud that runs all the way up to the top of the chase. Any ideas on how one would go about bracing the stud before cutting it. The exterior of the chase is brick so it's hard to say how much load it's carrying. I guess I could always get another stud of the same length and insert it into the chase from the chimney pipe hole in the top and place it more toward the rear of the chase where it will not interfere. Short of putting a new 15' stud a few inches away, is there another way to do it?

Take a look at this diagram...
http://farm5.static.flickr.com/4145/4987165711_e22e51b82b_b.jpg

Thanks

 

[Dakotas Dad]

Make a 2x6 doubled header, add short jack studs, cut offending stud, place header under it.

 

[73blazer]

While it's not required to insulate the full chase they do recommend it. Certainly with the triple wall duraplus your using, one may lean to the thought of not using, but the happiest thing you can do for you flue is keep it as hot as possible.
I fully insulated my 28' of chase w/ my Northstar (essentially same unit as 7100, although for some stupid reason, they don't certify the duraplus chimney which I much rather would have used), I used double wall air cooled chimney, and I'm very happy I fully insulated and type x drywalled the entire chase.
Give's just that little extra peace of mind. Hotter flue=less creosote, plus fully insulated and drywalled=extra fire protection.
Don't use durarock, it actually has a worse insulating value than drywall and will allow more heat to pass quicker.

 

[Gazerbeam]

Thanks for the replies. I think I have the framing part of it figured out now.

When I was looking closer as to where I would making the hole for the external combustion air intake, I discovered that the hole would be right at the intersection between the brick chase exterior side and the wall (for some reason, in my mind, I thought I could go straight out -not true). Take a look at the photo, it seems the centerline of the hole would be right at the intersection.
http://farm5.static.flickr.com/4115/4993131019_6e3962839e_z.jpg
It's a tight fit and I really don't have room for flex tubing and relocate the intake.

I was wondering it would be possible to simply frame in a channel that will connect the inlet on the fireplace and the external air intake. I know return air on central air is done similar to this when they route the return air between two 2x4s 16" apart.

Will this be an issue?

Thanks!!
http://farm5.static.flickr.com/4110/4993130999_5dd12c5b88_b.jpg

 

[tickbitty]

Love these drawings, what program are you doing them in?

 

[Gazerbeam]

Love these drawings, what program are you doing them in?

Thanks!! I made them in PowerPoint 2003. I Google for images of bricks, wood, insulation, exc. and use the images as a texture to fill in the rectangle and circle shapes. It's pretty easy and it really doesn't take as much time as you might think. Once you get started, most of it is simply a matter of copy-n-paste and then moving the shapes around the screen.