Moved into a house with a fireplace. There is a knob on the outside for the flue that I can move, but the way the furnace is built, I can't see flue itself so I don't know which w …

Is this something I should do every year? Or only when it seems like there's trouble?

My fireplace (which is kind of built like a wood stove, with a glass door) has a crack in the glass. That glass is expensive! Over $100 per square foot, so over $200 to replace t …