Hello, I am new to this forum and relatively new to heating with wood. I just installed a summer's heat add on furnace in the basement of my new construction home. The flu from the stove is connected to a masonry chimney with 8x12 clay flu liner. There is a fireplace with the separate flu but same chimney directly above the stove. About four hours after the initial firing there was a smoke smell around the fireplace in the floor above the stove. My chimney is probably 40-45 feet tall my stove is in the basement, the fireplace is on the first floor there is a second floor Plus attic plus however much the chimney is above the roof. Finally my question is: could the smoke coming all the way back down the chimney or is it somehow leaking into the other flu on it's way up? Thanks in advance for any comments.