Our longest idle was about 3 weeks ago when we had to go to the hospital for our new baby.
I loaded up the Mark II and we left at 5am Monday morning. I set the draft at 1/2 turn open. Out side temps were 25 at night and 45-50 daytime. This stove will idle at about 130 stack temp. I came back home at 1pm Tuesday to shake and reload the stove. There was a dull red bed with a little unburnt coal on top. I opened the draft control all the way and 15 min later it was cooking along pretty well. Easily hot enough to shake and reload. Stack temps went back up to 250 before I shook it down. If my math is correct, that was a 32 hour burn. There wasn't alot of heat, but it stayed going just like I hoped it would I shook it, refilled it, and reset it to get back to the hospital to hang out with my new son. We all came home at 3pm Wed so that next day was a 26 hour burn. He loves the stove room. When he gets fussy we take him in and turn on the stove blower if it's not already on and that helps to calm him down.