You really need to determine if you have a full insulated liner and if you have a block off plate. Have you checked the door gasket? This insert should easily be able to get 8 hour burn times.
I will be making those determinations for the sake of long-term optimal burning, although I'm not certain they would take me down the right path for the performance issues I'm having with this stove. I can snuff out the fire by shutting off the air, so if my door is leaking, it can't be awful. It may be making some sort of contribution. If I let it have a little air, it takes off like a rocket. I don't have a way to hook up a manometer to the flue, but the draft is very strong.
I run a Lopi freedom with a 29' insulated chimney 8 hours seems to be max on burn time. I usually reload between 6-8 hours. Occasionally I will go 10 hours but the blower is not running and its down to coals not much heat. I think the major problem is overdraft the secondary's seems to draw hard and eat through the wood but it does heat 1600 sq ft very well but not evenly. Once the wood is in the coal stage things slow down, The secondary flames seem to burn very hard and get sucked up in the top of the stove. I have a Napoleon 1401 (2.3sqft) at the other end of the house with a 19' chimney it easily gets 10hr burns sometimes up to 12.
The fire box in the the Lopi I find annoying I dislike east west loading and hate that trapezoid shape. I put 18" splits in the rear and 22" - 24" in the front. I can usually load 6 to 9 splits in it.
I think N/S loading would work better if my wood allowed it. I think my splits are too large for this stove, despite the large "volume" of the box, it just doesn't work out like my Ashford when trying to arrange things in there. I also have too many splits in the 18-22" range that prevents N/S. And when I load E/W, I have too many splits that are <16". They're too long to put end-to-end, and too short to effectively take up space. Large diameter splits just don't jive with the short height of the box. There's no room for arranging things properly, so it's hard to get the box packed tightly. The bad part is, I probably have 8 cord of wood that was cut/split with the Ashford in mind.
I am finding that I can get reloads to last a little longer than first loads. I'm probably getting more pounds of wood in the box without the kindling and paper, and I'm probably wasting less of it getting the fire established. My best burn yesterday out of three loads was about 6 hours to the last visible coals, and that was with maple. It provided plenty of heat during that time period. I'm not sure if the furnace ever kicked on either, but the main part of the house was comfortable enough.
In the long term, I want a stove that can go all night on fir, pine, or cedar. My old stove used to do that, and I was much happier with it. Those are just the needs we have. I'll keep fooling with this one to see how good I can get it, but I just doubt it will ever suit our needs. At the very least, perhaps I can get it usable for long enough to find a good deal on a Princess. I just don't know if I can fork out retail price again.
