Anyone out there familiar with BTU calcs for heating. I have run a couple of BTU calculators I found on the internet to figure what I am going to need to heat garage and they have come back anywhere from 8000btu's to 22000btu's. I have 24x24 garage with a ten foot ceiling, insulated door, r19 in ceiling and r13 in walls. Anyone with some real world experience in a cold climate (New England) that can tell me what they are heating with and how it's working out. I am looking at ventless propane units and also indoor kerosene heaters.