How hot should ducts get with a NG furnace? Seems like with oil there is always plenty of hot air coming from the vents. I have metal uninsulated ducts but still. My furnace has to run half hour before all my vents get warm air. This furnace doesnt seem to keep up when it is cold and I was firing off 300 therms last month in my 1500sq.ft. drafty house. Any ideas? I am about ready to go back to oil, I never had so much usage with oil in anyplace that I lived as I have had with NG.