I recently moved into a house with a jotul direct vent gas stove, probably Allagash. We turned the stove on for about 2 hours the other day. We checked the propane the day before and two days after we turned on the stove. Six gallons of propane (5 percent of a 120 gallon tank) was gone. Is this normal? If not, what could be the problem? The stove is controlled by a thermostat, so we just set it to 65 and then back to 50, when the house was warm enough.