I've gotten an even longer time once. I loaded up my Hitzer 983 insert and left for New Hampshire (I live in Conn) on a Wednesday MORNING to spend New Years with friends up there. Besides loading up the stove, we set the oil furnace thermostat at 60 degrees, figuring that after the coal fire died, the house would begin to cool and eventually the furnace would come on.
Due to an emergency, we had to come back on Friday and arrived back Friday NIGHT. To our surprise when we walked in the house it still felt warm.....I then felt the base boards but they were cool to the touch.....and then looked in the insert. To our surprise you could still see red coals glowing (although faintly) in about one third of the coal bed. The inside temperature was 65 degrees.
Still not believing it, I went down into the basement to check on the furnace. The basement was COLD!! The furnace and everything else in the cellar (steel shelving, oil tank, etc) was very cold to the touch, which means the FURNACE NEVER KICKED ON!!!
57 Hour Burn!!!
I should mention that the fire was almost out. The coal bed was CHOKED with ash, and most of the fire was out. But I was able to save the fire. It was actually more trouble than it was worth (to "save" the fire) and I only did it to have the bragging rights (one match all season). In order to save it I had to gradually add small pieces of kindling to the top of the still-glowing coals. I waited until the fire starting doing better (and it was mostly a wood fire at this point) , and I had the ashpan door open, before I began to remove the ashes. I removed about 3 or 4 ashpans full of ashes in the first 6 hours I was home. The next day, I removed 2 or 3 more. I'm sure I waisted some coal (and lots of time) bringing it back to life. That is where I came up with the theory "coal into stove = ash out of stove". Anyway, it was a lot of work to save it, but I can now say that I got a 57 hour burn time!!