Just moved into a house. Has a Scandia 325C. This is the first time in my adult life I've had a fireplace/insert. I have been tinkering with it but have no clue what i'm doing. It has 2 knobs one above the door and another above the stove. I know one is for air and the other for dampering? keeping the heat in the insert. I thought the top one dampered the chimney. I know I sound clueless probably because I am. I was told think of the top as gas and the bottom as air like on a carb?