Set the hopper in the highest position and you should be fine as long as it is good coal, meaning it shakes down fairly easily. Just set the thermostat so it does not overfire. Use a magnetic thermometer on the smoke pipe. Low fire 125 to 150 stack temp. High fire 200 to 250 stack temp.
If when the stove is cold the thermostat flap is closed when set at 1, then a low fire would correspond to a setting of about 3.5 and high about 4.5. It depends how the adjustment was made when new. Just lower the number if firing too hot.
If you meant chimney draft then the recommended draft is between .02 and .07.