ZC Fireplace & Chimney Replacement Questions

[Ryguy225]

I’ve been searching all over the forums, but I can’t seem to find the answer I’m looking for. Seeking help and some advice on a diy install.

Currently I have a Marco ZC with 8” Firecraft FTF8 air cooled chimney and eventually I’d like to replace it with something more efficient. It’s installed in an insulated external chase that does not pass through any floors or the attic. The chase shares a vent pipe for the furnace and hvac trunk for the 2nd floor. There’s two fire stops in the chase with radiation shields.

Eventually I’d like to replace the Marco with a high efficiency wood burning fireplace, most of them call for 6” pipe. I’m just at a loss for what I need to change out. I know I’ll need a new chase cap because the new pipe is smaller, but what about the fire stops? Can the 6” pass through the current radiation shields or do they need to be sized for the outside diameter of the pipe?

 

[begreen]

Some of the larger fireplaces take 7" or 8" chimney pipe. The big difference is that most of them don't use air-cooled chimney pipe. The difference in diameter will likely mean an adapting plate to seal firestops, new supports, and possibly a new chase top cap. The firestops might just need a metal plate or donut with a hole cut into it that fits the chimney. This plate would get attached to the existing firestop ring.

What condition is the chase cap in? What material was used? Pictures are welcome.

 

[Ryguy225]

Some of the larger fireplaces take 7" or 8" chimney pipe. The big difference is that most of them don't use air-cooled chimney pipe. The difference in diameter will likely mean an adapting plate to seal firestops, new supports, and possibly a new chase top cap. The firestops might just need a metal plate or donut with a hole cut into it that fits the chimney. This plate would get attached to the existing firestop ring.

What condition is the chase cap in? What material was used? Pictures are welcome.

Chase cap is metal, condition looks ok I guess, but I haven’t been up on the roof yet. Here’s a pic attached. My main issue I’m having with selecting a new unit is I have about 39 5/8” space between the hvac trunk and the furnace pipe in the chase. Not looking forward to building a bump out and modifying the wood flooring too much around my current hearth.