Conclusion:
- I want to put my reactor back in the exhaust pipe.
- I think it would take more space in my reactor the diameter of the axis is 18 and the diameter of the tube 20, I think to put 17 see 16 and leave 20 for the tube.
-To stop breaking my copper pipe I think to put sanitary hoses.
For the space between the rod and the envelope you should stay within the tolerance that gives you André.
For the deposits in the pipes .... it takes your breath away, on my installation, the deposit is much more distributed, without "nodules". What exactly do you put like water, mineral water?
For the broken pipe, you can have too much effort / fatigue when the exhaust line expands or vibrates certain plans. One of the solutions is to braze a piece of copper pipe of a maximum of ten cm for the inlet / outlet of the reactor. Then comes a flexible connection (rubber or better silicone) long enough to absorb the movements of the exhaust line (this can move several cm!). The end of the piping to destination can be made in flexible or rigid.