Unlike yours, the pipe added onto my telescoping unit is attached to the outer wall and does not sit on the stove. It is sitting (resting) on the inner pipe and has a 1/4" gap I stuffed with stove rope for a complete seal. I would say either way works. Check for leakage with an incense stick from a pot shop. With all my stoves, this connection was never secured with screws-just gravity. An imperfect mechanical connection but it works. Easy disassembly too.