Twenty four hours at what temp?30's maybe,low teens 10 to 12 hrs realistically.Not knocking the stove in any way shape or form,just speaking from experiences relayed to me by two friends and one relative who own them.A beautiful stove ,seems well built,but 24 hours isn't a reality in low teen or sub teen temps.The BK will burn 40 hrs in 30 degree weather ,but not much usable heat. Coals,and a quick start up with dry wood is a reasonable expectation.Twenty four hours with BK's 4,4 cube firebox ,and serious dry hardwood is not only a reality but an expectation,this can be achieved with temps in the low teens and sub teens ,I don't go for marathon burning scenarios when temps dip into the 5 to 10 degree range,I know I'll get 15 hours with a house kept in the 70's,I don't ask anymore of a stove than that.That in itself is a feat ,I've had many stoves and know a little about what is fact and what is fiction.