What kind of stove is it? A modern catalytic stove will give you crazy long burn times. I have a Heartstone Green Mountain 60. I load it up at 9pm, and at 8am I still have a thick hot bed of coals and the stove itself is still wicked hot. I just throw more wood in and it takes off by itself.

These stoves work by recycling and burning the smoke the fire gives off. The important thing with these stoves is you need a professional with experience with these types of stoves to install it.