The overnight burn ability of the Pyro Classic (Pyroclassic IV) is 100% dependent on the quality and size of fuel you put in it.
You will need to have a good ember bed established, then add 2 or 3 dry hardwood logs (preferably Kanuka) measuring approximately 400mm long by 120mm thick into the fire box. Allow the flames to establish on the front ends of the logs and then ensure the turboslide is fully closed meaning the air flow into the fire is controlled by the fire itself. The further back in the fire chamber you have the fire the longer it will burn for.
Remember, you need to add a kilo of fuel for every hour burn time required. If you follow these instructions you should have some hot embers left in the back of the fire chamber in the morning ready to be brought forward to establish another fire.
As a point of caution you should never insert a fresh log which is too large or placed in the fire too late to ensure a flaming combustion, doing this will cook the wood fuel on the remaining embers releasing unburnt volatile gases into the combustion chamber which will eventually reach a point of ignition, this can result in a sizable explosion inside the fire chamber and may cause damage to the unit.