I have acquired a house with a Heat n Glo propane zero clearance gas log fireplace. The flue is a six inch protrusion right out the back behind the house. The combustion air appears to come from the bottom front of the fireplace, inside the house. Question: So how much of the forced air heat in the house is going through the fireplace and out that 6" flue? I have been busy sealing cracks, adding insulation, and getting insulated window treatments; I just now got to looking at the insert. I don't need the fireplace for heat, and with the open floorplan any "space heating" heats the entire house; any function the fireplace might have would be purely decorative. If I am losing any of my expensive propane heat out that thing it is a liablility. Any help would be appreciated.