Fran, with our new 7100 (approx. 6 weeks) we have both radiant heat coming from the box and hot moving air coming from the top. There are many variables to getting a good fire: dry wood (less than 20% moisture), we use anywhere from 5-8 pieces that are 18"-20" long, dry kindling (twigs, pine cones, or small split branches) under the wood, and twisted double sheets of newspaper underneath the kindling, if you are starting cold. We tend not to use fireplace matches but favor a propane torch, just our preference. It gets things going quicker. As others have said once you start it, keep the doors overlapping one another for additional air. We use right over left. We close the doors tight once a burn has begun. Be patient because it can take a few minutes (approx. 10 give or take) to get going. We also tend to let the blower come on by itself, but if the room is chilly we will flip the blower switch on once the fire is active and the box is heating up nicely.
With respect to dark soot accumulation we see some in the corners, once in a while. Sometimes a really slow start-up or the cool-down will produce dark soot. To a certain extent it is unavoidable. It's a question of degree. A good hot fire will burn off a great deal of the dark soot,. I believe the blower will also assist in the "washing" of the glass. We do get a lighter light tan-colored soot on the glass but it doesn't interfere with seeing the fire. That just goes with the territory and is normal. This glass is very easy to clean. I use vinegar sprayed on a paper towel for the light soot and dip the wet paper towel in the powdery ash to scrub the darker soot.
I hope this has helped you. We are fairly new to wood burning. This is our third year.
