Well, I guess Slow1 doesn't fit the heat sink theory. I've been running 24/7 with twice a day loads for a couple months (with the occasional break in warmer temps). You are right that loading on coals with a warm stove really extends the burn time. Once I get rolling 24/7 I just always seems to have a nice coal bed and I'm usually engaging the cat in less than 10 minutes after a reload. Occasionally, I'll open the draft to burn the coals down some because I've got too many. It is just strange that you don't have coals after 12 hours unless you stuff the stove. Maybe when you're around all day, try several really small consective loads (small enough that it won't overheat your house) to build up a nice coal bed. Then try loading about 60 or 70% for the night on that coal bed and see what happens.