Pellet stove where zero clearance fireplace is

[Dshea]

First time here tia , I wanna install a pellet insert in a existing zero clearance fire place without . After removing the refractory panels I may need more clearance . If I cut through the sheemetal for clearance should I patch any holes and the same for the 4” flue going through the existing flue ?
I’m trying to possibly cut down on drafts .

 

[DAKSY]

If your ZC fireplace is on an outside wall & you want to cut OUT all drafts,
pull the ZC box, the chimney pipe & cap.
Seal the entire chase from the envelope of the house, including the chase top,
& run a horizontal vent with an OAK.
If your install is on an interior wall, I would also rip out the stove & chimney & install a sealed pellet
system from the unit to the cap, also with an OAK.
If you know what pellet stove you want, check the manual for approved installations.
If done properly, this could fall under an "alcove" installation.
The manual will tell you what is required to do that.