What is the ideal operating temperature range of the fire?

There is no ‘max temp’ for a Pyroclassic, the ceramic cylinder has an operating range safe up to 1450 Celsius and the maximum temp wood fuel can burn at is 1100 Celsius in optimum conditions.   The door glass will emit heat at approx. 350 Celsius and the top plate typically gets to a maximum of 550-600 Celsius during high fire burn cycles. The fire is designed to withstand and tolerate these temps over and over again with no stress to the unit, there is no welded box to fatigue under expansion in a Pyroclassic and so to answer your question no there is no maximum limit.