We are replacing our zero clearance wood stove with a stand alone Quadra fire aisle Royale wood stove. I have ripped out the old ZC and prefab hearth and laid porcelain tile. My question is can i tie into the existing 12" double wall pipe? The pipe is 12" outer with a 8" inner stainless steel pipe. I need to adapt it to 6" single wall but the over the shelf adapter won't fit the stainless pipe. Then i still the problem of how to cap off the void between the 12" and 8". Anyone else done this? Anything commercially available? Ive spent hours looking and can't find anything.