Hi again folks. So our stove (quad 5100I) been set up now for a month or so and we are very pleased with it so far, nice heat, warm floors, makes me very sleepy when I sit near it etc. and we are ready to move on to the next step, moving some air around. My wife and I have reasearched floor vents and have found many attractive styles to choose from and even ones that close when (god forbid) there is a fire, but we never realized there were so many different sizes available. So heres the situation, we have a centrally located masonary chimney (20'L X 4'd X30'h block with stone front/sides) extending from the basement floor to about the middle of the attic where it gets norrower and exits the roof (there are 3 chimineys in the structure, B ment FP, LR FP,oil burner). At the base of the chimney in the basement is our insert and directly behind the back wall of the chimney structure is the stairwell leading up or down depending on wich way you are going. As things are right now we have a 8-12deg difference (depending) in temp between the upstairs(groung floor) and basement and want to install some return vents in the floors of 3 rooms furthest from the stairwell to help bring up some of the warm air from the basement. So the question of the day is....... How do you dertermine how large of a vent (vents) to use? I would like to have this setup with two things in mind, not using vents that are larger in size than needed and letting natrual convection do the work of moving the air rather than fans. I have given thought to ducting the vents together and using a duct booster fan to move air but I would think with the right size vents gravity will do the work. I'm planning on installing three vents, one of witch will be in the room with the thermostat for this end of the house witch is another reason I dont want to use a duct fan over convection in the event the basement gets cooler than the upstairs. Any ideas or formulas to help figure this out ?