I used an old 100lb propane tank measuring 14.25" internal dia. 6" pipe for the fire box and vertical. Used 2000*f header wrap as insulation. Exhaust is 6" out the bottom. Won't draft at all.. Had 1.75" clearance from the riser, figured that was the issue, cut .5" off leaving 2.25 clearance. Made a slight difference but not tons
Any ideas??? Pipe is .25" wall