Thanks in advance for anyone who is willing to throw their two cents in: We are in the process of renovating a town house which has an adjoining house on either side, and a facade which is considered " historic" and cannot be altered. The current kitchen has electric range with a recirculating microwave hood. As a result anything that is cooked there lingers for days. We are planning on remodeling the kitchen entirely and are installing a induction range and wanted to install a hood. Our issues are the following: 1) the hood can only be vented to the roof( two floors up) or the back patio. Our contractor was suggesting, as an alternative, tapping into the ductwork for the bathroom( no shower, just toilet) on the same floor that has a fan and using its ductwork to vent to the back patio. They want to install a flap system to keep odors from being vented into the bathroom. I am concerned about that in a general sense and wonder if anyone has specific concerns that I should discuss with my contractor about that plan. 2) Make up air--does anyone have experience putting a make-up air system into their house without redoing HVAC? That would increase cost significantly and would like to avoid it. Thanks