how do you fit the regular vent pipe into the regular->typeB adapter? i am confused because the regular side of the adapter has two walls but they are spread apart kind of like the female side on a regular type B fitting. if i take a crimped end of a regular pipe, it will fit inside the inner loop but if i take an uncrimped end, it fits in between the two walls. i am inclined to think the latter is correct. just checking cause i wanna be 100% sure my gas venting is done right.