Making it safer advice on a wood stove opening

[begreen]

It makes the most sense to proceed as bholler suggested. The chimney pipe would terminate with a class A tee in the chase with a snout that passes through the granite via a class A thimble. This would get a trim collar on the granite face to make it look trim and tidy.
I would also remove the current hearth extension and wood storage box underneath. Then there will be enough height for the BK40 to top vent up 2-3 ft before a 90 into the class A thimble. The hole where the old firebox was can get a removable black metal cover, or something fancier if desired.

 

[Teachme]

It makes the most sense to proceed as bholler suggested. The chimney pipe would terminate with a class A tee in the chase with a snout that passes through the granite via a class A thimble. This would get a trim collar on the granite face to make it look trim and tidy.
I would also remove the current hearth extension and wood storage box underneath. Then there will be enough height for the BK40 to top vent up 2-3 ft before a 90 into the class A thimble. The hole where the old firebox was can get a removable black metal cover, or something fancier if desired.

The current hearth extension and wood storage box underneath I am planing in removing. One of the problems is that there’s a mantle above that’s about 10 inches sticking out of 2 inch granite.

 

[bholler]

The current hearth extension and wood storage box underneath I am planing in removing. One of the problems is that there’s a mantle above that’s about 10 inches sticking out of 2 inch granite.

So put the pipe back against the mantle. That will put the back of the stove 6" or so from the face of the fireplace. I wouldnt want it closer than that anyway for servicing purposes

 

[begreen]

Agreed. The mantel is stone, right? If so there isn't a clearance issue with the stove pipe.

 

[BKVP]

Let me weigh in a bit here. There is ZERO safety testing that shows a Class A system can be run inside an existing factory build fireplace chimney. To be 100% clear, I am certain other have done so. However, if there was ever an insurance claim related to this project, the venting manufacturer would state "our product was never designed to be run inside an existing metal manufactured chimney."

Bholler is correct. Run the Class A and yank the old pipe. Second, you will need to find a method to support the Class A pipe. The stove is not rated to carry the weight of the Class A pipe.

By the way, nice fireplace! Should be spectacular when done and even better when done correct/safely.

BKVP

 

[BKVP]

Class A is typically exposed to cooler temperatures of attic or outside air. The question at hand, is what will the temperatures be inside the space between the old venting and the Class A? That is what has never been tested. Class A clearances are not based upon this scenario; perhaps the temps are so high it requires much greater clearances. Then, the next issue is will the Class A mfg warranty their product against failure given the potential for excessive temps.

BKVP