Give your home a heating upgrade with this DVL 8 in. Diameter 18 in. Length Double-Wall Chimney Pipe! Designed for installation with minimum clearance to combustibles (6 in. to walls, 8 in. from top of horizontal run to ceiling), this chimney piping ensures hyper efficiency. Its double-wall, air-insulated design reduces clearances to combustibles from 18 to 6, also helping efficiency. Constructed with a stainless-steel inner wall, you can count on this piping for years to come.