I have an old VC Defiant from the late 70's early 80's. I have 8 inch single wall stovepipe. From the top of the stove it goes up 8 inches into an elbow into another 8 inch into a masonry chimney. The chimney is made with 10 X 10 clay flues the chimney extends 35 feet above when the stove connects. It seems like I have a good draft you can feel it when you put your hand in the stove and when I put a lit cigar even 6 inches from the outside of the front doors you can see it pulling the smoke in and up. I dont know if thats a viable test but it showed me I have draft. My problem when I go to start a fire I to get it going I have used cedar firestarters, fatwood both with newspaper and kinling. The fire gets going good then when I put some wood on it seems to get going good. I am using seasoned hardwoods bought a cord. Well after 15 20 minutes the flames smolder out. What I have left is glowing chared wood and the temp begins to drop. This occurs both with the doors open like a fireplace and with the doors closed in vertical burn. So I dont think it as air issue because with the doors open it is getting plenty of air? When I close the doors the flames increase, but only for a short time. Then they fade out. Usually after this goes on for sometime I get frustrated and put in a enviro-log or a duraflame to get it going with the doors open just to keep the flames then I slowly add wood. After some time maybe 1-3 hours I finally get it hot enough to sustain a fire. 350 - 400 gridle temp using a laser temp reader. Once I cant get the stove over 350- 380 I just load it up and wait the temp drops and then it comes up to again 375 or so then I put into secondary burn and it drop a bit in temp maybe to 330. It will heat for several hours.But again can not get the temp higher 500 - 600. What am I doing wrong or any suggestions.