Ok this is strange. I recently bought as house with a ventless fireplace. Two things are going on. 1. If I keep the setting on low, the fireplace will shut off in about 15min. Even when I turn it back on it will only stay lit for about 5min unless I turn it higher. I have to keep it on high for it to stay on. 2. I have a major draft comming from the base of the fireplace where the bottom vents are. I can feel the air from the outside comming in especialy when it is below 30. This a ventless heater so there is nothing to shut right? I looked outside and there is no vent anywhere. The top of the roof where the chiminy is has shingles over it and there is nothing poking out the sides. Any ideas?