franco b: Thanks, I'll try that:
1.) Add 1 shovel-full of coal (is that what you meant by "adding a shovel of coal"?);
2.) Open the air to high;
3.) Once that is burning, shake down;
4.) Add more coal immediately and turn air down to medium;
5.) Turn to low once gasses are burning.
When I do add coal I leave the glass (top) door open till I see some blue flames, Then I turn the air down, close the door, and still see blue flames for about 5 minutes, then they slowly disappear.
QUESTION: Is 5 minutes of blue flames enough time to be mostly assured that the puffback danger time is over?
...because I do get blue flames, they just go out sooner than I thought they should, but maybe I'm OK.
Here's a photo of my setup for those who wonder if I have enough draft. Since I am a novice, I don't know what strong draft is, but if I had to say, I'd say I have strong draft. The blue flames go out when too much air is flowing, I can reproduce this every time by sliding the air intake to full air and the flames go out (just like franco said). So if I have enough draft to blow out the blue flames, I'm thinking I probably have enough draft overall. This place was built to burn coal. It's a ranch with a fully exposed (above grade facing south) finished lower level with vents in the ceiling to heat the rest of the house optionally. So, I'd feel confident that the draft in the chimney was designed well; it's just my black stove pipe that could be the problem, I guess.
franco: thank you for the detailed info! every post you've added to this thread have details I need. What I truly crave are the abstract ideas and processes behind everything so I can universally apply the info to any situation/coal burner. Me knowing what causes puffbacks in general is really all I need to know; If I know that, I can prevent them in ANY situation.