I'm new to this Pellet Stove stuff and am getting a Lopi Leyden freestanding stove installed in Sept. It will vent right up my existing 8" fireplace flue with its own 4" liner. Question: Do I need to have an air intake line installed? And if so, is this done in the same flue? I thought I didn't need one and the owner of the Fireplace store didn't say otherwise. Thanks a bunch.