rocket mass heater: flexi pipe

Is this stuff okay to use?

Paul, it might help if you specify where exactly where you would use it in your set-up and how long of a piece your hoping to use.

I assume you are thinking of just using this through your exterior wall.... 18" or less - is this what your thinking?

Looks like it might be great for an intake-air duct, are you planning on supplying outside air?

Any part.  Including inside the thermal mass.

nope the rings on the inside slow the flow to much and create a back pressure in the stove. i sure wish it would work theres some stuff i would love to build that it would be perfect for.