What does it mean by the Pyroclassic being 'Self Regulating'?

The vigorous fire near the loading door automatically slows down as the burning front advances through the firebox towards the back. Each cycle ends with ash and hot ember at the far end of the firebox. Only use the Turboslide when lighting, adding fresh fuel or if you quickly want a very vigorous fire. The Pyroclassic® IV not only provides heat soon after start up but it also stores a lot of the heat from burning your wood, you will get most of this heat back over several hours. Frequent reloading may result in high room temperatures but you will soon know how much and how often to add fuel, the best heater output control is how much and how often you do this. The Pyroclassic® IV is designed to save on firewood and to keep emission levels to the minimum by storing the surplus heat which normally goes up the chimney - this heat is still being released into the room even when the fire is low at the end of each burn cycle.