So to adapt a wood burning stove to burn coal, you just have to increase the oxygen supply?
It was about 2007 when I set mine up, and I did a lot of research, so some of the information I found and still recall was on forums and such. The closest model they still show is this
https://www.usstove.com/product/1800-sq-ft-coal-only-circulator-stove/ and there's a user manual there, but it doesn't really explain the use of the door vents. The front bottom of the firebox has a vent connected to a knob that adjusts it, and that's the only one I've ever used. The knob has a thermostat that can be fully open while it's heating up, and slowly closes as it gets hotter, very nice to have. All I can remember about the door vents and burning coals connections must have come from a forum or something similar.
That thing's heavy too, weighs about 250 pounds, has a firebox inner, and metal cover outer all around(even when it's hot a kid could touch it and not get burned). Mine's up on blocks about 7 inches off the floor
Also all I've ever used in it is wood, and their descriptions of its use have changed since then. likely due to regulations