I am getting ready to finish my basement (townhouse) in MD. I have a Lennox G26, 75,000 BTU furnace. It has a combustion air intake from outside, but I am wondering if that alone will fill the requirement for the combustion air, or if I will need to install an intake from an adjoining room. Currently my plan calls for the furnace room to remain unfinished and it is approx 1025 cubic feet. Appreciate the help. Thanks.