Was wondering if there was a better or proper way of creating a better insulated chimney. House was built in 1956 and has a chimney stack of cinder blocks running from basment up, inside space is 7 x 7 opening. My furnace is plumbed into the stack at about 6 foot height. Was wondering if a new metal stack was run from top to bottom with a cap and insulation dropped down sides would save me some heat loss. ? how would you support it and is this possible or plain stuid .... help.