It's on the back side of the instruction sheet with the stop sign on it in the "Building A Fire" directions #6. This unit is designed to function effectively when air is allowed to circulate to all areas of the firebox. An ideal means of achieving this is to rake a slight (1"-2" wide) trough in the center of the coal bed from front to back prior to loading the fuel. Works great for me doing it this way. I loaded up at 11:00 last night and woke up at 7:30 this morning to a warm house and had no problem getting another fire going from the coals.