Hello I have just aquired a used superior wrt4826wh. I have read over the instruction manual but when in comes to the chimney starter collar/ adapter the instructions are pretty vague. When I look down inside the top of the unit I can see the outside shell with a 4 inch knock out on the back. The baffle / catalysts bypass has a slide bar that moves when you pull a knob. For the life of me nothing I find looks like it would hook up properly. I am beginning to think I am missing a part. I am going to go with a stainless triple wall 7" pipe straight run, fire stop, roof flashing . To 3 wall brackets and 1 roof. Connecting to the fire place is my only issue.