Well it won't burn as fast with a damper installed and closed down to just enough air flow. Do these things have a draft on the front? From the stand point of using a regular indoor stove, if you put the damper down low and open the draft to half your stove will throw a lot more heat in a room. With no draft and closing down the damper, it will give you a longer burn, the heat you get will vary with moisture. The dryer the more heat off it. Green wood is just going to smolder. I notice this with an old cast iron stove in the shop. I can have a fire for several hours with good dry wood and get lots of heat, actually too hot when in there working. I have to open the door up.
I also notice, when using my boiler for my steamer, an open draft and an almost closed damper really makes her boil. But with the draft open you are burning faster to. Just ain't going up the flu in heaps if the damper is closed down low.
You'll also learn this when cooking with a wood burning kitchen stove.
