My oslo has 6 inch double wall pipe going through the wall into an exterior brick chimney, 2x2 foot chimney with an 8x8 inch clay liner, about 24 feet tall.
I burned about 6 or 8 chunks of red oak and ash last night, had it loaded at 9pm, had the air completely shut off at 9:30pm, secondary burn in full swing, stove top temp. was 500 degrees f. and this morning at 5:30 a.m. I raked the coals around and threw a couple more chunks in there just to keep 'er warm til I get home at around 4pm. Yesterday at 4 pm there were still enough hot coals to fire it right back up, and that was after 10.5 hours.
I'm not even burning the long stuff yet, this is on chunk wood, but good quality, dry, seasoned over a year and a half, oak and ash.
Sooooo,
how's your chimney set up, as draft will affect burn time?
also, what and how much wood you stuffin' that puppy with?
I always, always, have hot coals to refire in the morning, especially when I start serious burnin'.
put a big old round of oak, cherry, walnut, hickory, or the like, maybe 8 incher and 22 inches long, in the back of that oslo at night, stuff it in front and on top with whatever else you got, take her up to about 600 degrees with wide open air, shut her down to half air for 10 minutes, then down to a quarter for another 10 minutes, then you can likely shut off the air and go to bed.....should be fat red coals in there in the morning.