Zero clearance wood Fireplace venting

[Oatman174500]

I am replacing my old zero clearance wood-burning fireplace with a new one.
My existing venting is about 10 inches round pipe that runs to the roof.
The new fireplace required 6" venting.
My question if anybody can help is can I run the new venting inside of the existing 10 inch vent so that I do not have to remove the existing venting
thanks

 

[begreen]

The odds are that the old fireplace had an air cooled chimney pipe. The new fireplace will require all-new, class A chimney piping.

 

[Oatman174500]

I understand that, I probably was not really clear.
I would prefer not to tear out the existing vent pipe and just run the new vent pipe inside the old pipe.
Not sure if this is a good idea or if I should just bite the bullet and tear out the out and put in the new
thanks for getting back to me
I am really confused

 

[begreen]

It is not permitted. The new fireplace must be installed per code and the manufacturer's requirements.

 

[bholler]

It also doubt it would be possible. The fireplace is almost always what is supporting the chimney so you really can't remove the fireplace without taking out the chimney