ICC Excel Chimney Parts Questions

[WarmIsbetter]

I'm installing a 42" Apex fireplace in a "new construction" (actually a remodel) scenario. Excel 7" piping is approved and I intend to use that.

Photos attached of the current rough opening. Notes:

• Ignore wood bar stockings are hung from, it's just temporary.
• Fireplace will be installed on platform approx 20" above floor
• I have a cathedral ceiling, but it won't be visible once we have finished the fireplace opening with stone
• In the upclose photo of the roof, there is a small black dot just under the wood brace between the rafters, that is the center of the chimney pipe once the appliance is installed
  • I'll need a slight offset to get the pipe far enough away from the rafter on the right
• The wood bracing between the rafters will be removed
• There is metal angle iron that runs from the rear to the front just inside both visible rafters. I installed that to help with adding horizontal blocking if needed. I believe that would give me similar install options as if the ceiling were flat?
• The roof decking and then metal roof is directly on top of the visible rafters (i.e. no attic space).
• Chimney needs to extend ~13' above appliance

I've read through the install instructions for the ICC chimney as well as the Apex. I have a couple questions still:

1. The Excel install instructions say that I should use a round or square support for a cathedral ceiling/roof. The vendor for the pipe (Friendly Fires online store) quoted me a radiation shield instead. I guess I could block it out and use a radiation shield and attic shield to keep the insulation away from the pipe. What's the correct way to do this? I like the idea of not using the support as that means I don't have to precisely size the pipe between the appliance and bottom of the support, but it's not that big of a deal. I also want to run class A pipe all the way and it seems like the support boxes are designed to have double wall pipe under them.
2. I'll need a small offset, about 4". Do I need an offset support with that?
3. Are there other questions I should be asking?

Thanks in advance.

 

[begreen]

Is the roof slope just above this fireplace? A firestop is required for each floor penetration, but if there is none, then the ZC will support the chimney.

30º 7" elbows back to back will provide a 3" offset. If there is room, a 12" section between two 15º elbows will provide a 4" offset. For other options check the offset tables in the Excel installation manual. Download it for more details.

Besides the minimum height, the chimney also needs to honor the 10-3-2 rule on the outside.


As an aside, the chase will get warm. Is the foam going to be protected? Will it offgas when heated?

 

[WarmIsbetter]

Beegreen, thanks for your reply.

Is the roof slope just above this fireplace?

Yes. No second floor. No attic space.

A firestop is required for each floor penetration, but if there is none, then the ZC will support the chimney.

What does "ZC" mean in this context?

10-4 on the offsets and chimney height.

As an aside, the chase will get warm. Is the foam going to be protected? Will it offgas when heated?

I intend to install concrete board over the exposed studs before installing the appliance and piping. So there should not be any exposed insulation.

 

[begreen]

ZC = zero clearance fireplace, ie: the Apex.