I have a prefab wood burning fireplace a tractor and trailer couldn’t haul the wood I’ve burned in this thru the years. Has an 11” inside diameter pipe that is double walled runs straight up 25’ out of the ceiling. Fireplace is rock on 4 sides in middle of room, it’s 6’ x 3’ and there is at least 2’ of space on any side of prefab chimney double walled pipe inside the rock area where pipe runs up. I’m wanting to put a woodstove in front of fireplace sitting on the hearth which is more than big enough for a woodstove stove to sit. The stove I’m wanting to install uses 6” pipe for flu. So question is can I use 6” insulated stainless steel flu pipe inside the 11” to use for my woodstove? So it would be 25’ of insulated flexible 6” flu pipe connecting to a “T” off the back of the stove to connect to pipe. The stove is a Jøtul 602. Is there any reason this wouldn’t work and be safe.