Trouble with the flue liner installation, Jøtul C550 V2

[PeterZie]

We're doing work on a 1916 historic home, currently only have a gas fireplace insert installed no other forms of heat at the moment.
We were awaiting with excitement the installation of your tool C550 wood-burning insert last Monday. The installers have ordered a 6-inch stainless steel liner with 1/4-inch insulation specifically to fit a clay flue with a 7 x 13-inch internal dimension. They got a little stuck during installation. They run the camera down the chimney and discovered one offset tile a few feet below the top, and then there are three bends later, further down, to go around the second-story fireplace. This insert will be installed on the first story. The chimney is over 30 ft in length.
The installer gave me two options:

1. Break the clay flue and install the liner. They were discouraging me from doing this option because the clay flues are in really good condition.
2. Install a 5.5-inch stainless liner and then pour vermiculite around it (loose vermiculite, I believe, TBC).

Jøtul specifies in the manual that the minimum liner dimension is 6 inches. Since we are in a bit of a pickle for heating, I agreed to have the 5.5-inch liner, but after reading some more materials from Jøtul, it seems like that could be problematic. Now I'm leaning towards breaking only the offset tile and maybe a little bit more tile at the bends. I understand they're in good condition, but since we'll be using a wood-burning insert, the state of the tiles will not matter so much. I'm also wondering if undersizing the liner by roughly 16% will affect the performance or if it's even advisable. I will discuss this with the installers tomorrow, but any advice will be greatly appreciated.

 

[begreen]

The 5.5 liner should be ok, it might even be a benefit. The tall, 30' liner is likely to be more of an issue than the downsizing. The odds are the draft is going to be very strong. Did you ask the dealer what the Jotul recommended range for draft is for the new insert? Will they be testing this to be sure it's within the Jotul spec?