for 15 years and have very little soot on deck. We run it at the lowest setting or "1" or "1.5" most of the time. In the dead of winter we have had it up to "3" with the highest setting "4" but always turn it back to "2" prior to going to sleep. The problem with diesel heaters is getting them started without a drift back of smoke while the thing heats up so there is a draft. It took me several years to figure it out and during that time I thought that there wasn't much you could do about it. One day I hit on the idea of using a 2 inch by 2 inch computer muffin fan to cause the draft until the unit got hot enough. I have it connected to a cigarette lighter socket plug and just plug it in and hold it under the heater for about 3 or 4 minutes while first lighting it. It cuts the lighting process time down by 2/3rds and I never get any soot drift back. I noticed some time back that some of the new heaters come with some type of fan but I don't know if they are for lighting or running all the time. Mine uses very little fuel and is connected to a 2 gallon day tank that sits behind the heater. It's plumbed into the main tank and uses a small fuel pump the pump the fuel to the day tank.