I just purchased a Jotul F 600. I will be using an existing masonry stack from the basement through 2 floors. When opening the clean out door too the masonry stack, I can hear the draft. I'm running 6" pipe, and the stove will be placed to the left of the stack about 24 inches. My question is, what is the best type, most efficient, run to build? One or two elbows? Or does it matter?