These Shutter Fans are great for exhausting 
larger sized rooms and spaces.  Remember when using these fans that for 
every cubic foot per minute exhausted, you will need to allow for proper make-up 
air to enter the area you are exhausting.  To calculate proper ventilation, 
divide fan cfm by 750 to give you an idea of how much sq. ft of venting you will 
need. 
Please make sure adequate make-up air  is supplied when running any exhaust 
fan.  The potential for back drafting can occur with these type exhaust 
fans.  That means devices such as gas water heaters and gas furnaces in the 
same rooms as these exhaust fans,  where there is no source of make-up air 
will pull air from the path of least resistance.  This could include, your 
water heater vent pipe, furnace vent pipe, etc.  The potential exists that 
gas from these appliances could also be pulled into the area you are exhausting.