Wow, well that jives with my normal internal flue temps of 800 so I guess we've both got this figured out. External temps of 650 are really high.
I have a telescoping double wall pipe with the metal on metal that you speak of. I find the outside of the pipe noticeably colder in the overlap area. I can actually feel where the overlap starts and stops. I would want that stick on meter in the single wall section if that's possible.
If I set my air to 1/4 open with a loaded stove and leave it then it will overfire. That's my no f-in around setting.
I have a telescoping double wall pipe with the metal on metal that you speak of. I find the outside of the pipe noticeably colder in the overlap area. I can actually feel where the overlap starts and stops. I would want that stick on meter in the single wall section if that's possible.
If I set my air to 1/4 open with a loaded stove and leave it then it will overfire. That's my no f-in around setting.