About 10 years ago we bought a used Waterford Stanley that was about 30 years old THEN. We use it to heat a 22ft Mongolian yurt in Northern Ontario, and even in -40 degC weather it is never really being pushed to its limit. We usually let it go out during the night and relight early in the morning. I think it weighs around 700 pounds, so it holds a LOT of heat, long after the fire is dead and gone.
Ben Falk did a great video showcasing the capabilities of this stove: