Recently I purchased an Englander 30 for my daugher. Built the pad Saturday and tomorrow will grout the tile. On Saturday we did a short burn out doors, lasted about 20 minutes. Did another on Sunday for about 30 minutes. Want to do another tomorrow. Here's the problem...manual says to start a fire an close the door. If I do that the fire will be out in about 10 seconds. Have to leave the door cracked about 1/4" to keep the fire going. After the first burn I clean out the fire box and checked to see where the air enter the unit and if the air was getting into the fire box. Used the blower on my vaccum and air could be felt coming out of the small ledge above and behind the door. Tried working the damper and it would shut off the air supply. So that seems to be working. Have about 4' of chimney installed for the burn off process. Where am I going wrong? Any help would be greatly appeciated.