the answer must be an umbrella.
An umbrella is thin and narrow when it is down, so it can fit through the narrow opening of a chimney.
And when an umbrella is up, it is too large to fit through the same narrow opening.
so answer is 'UMBRELLA'.
Is it Smoke................
I can go up and down at the same time
I cannot move on my own
I work best when two people are working me
What am I?