Looking to install an englander stove. The previous stove that we removed had a 6 in diameter pipe that went through an 8 inch single walled pipe that extends from the attic floor to the chimney cap. The 6 inch pipe was held in place by metal rings inside the 8 inch pipe. We removed the 6 inch pipe however the 8 inch pipe remains in place. I know it is recommended that only triple wall or double walled insulated pipe go through the attic however, Im wondering if in this case it would be suitable to run Duravent DVL 6 inch diameter pipe through the 8 in pipe. The DVL 6 inch pipe is the only pipe that would fit snug inside the rings of the 8 inch pipe as it has an OD of 7 inches. Hope this makes sense.