Hi.. I have a over the range microwave which has a 300 cfm fan.. which doesn't do much I was thinking of installing an 2x24x5ft (2 inches depth 24 inces width 5 feet tall )duct work to vent out the heat and attaching it with a 720 cfm inline fan on top.as th etop of the duct will be going in ti the attic.. your response would be.. helpfull do you think this will work.. thanking you in advance..