Just to give you an example, we can run our stove top at 650 and the flue temperature will be around 350 or maybe just above that. If the stove top is below 550 the flue is never over 350 and sometimes much lower. Only on reloads does the flue temperature rise up. Once it hits 500 we have the draft down and the cat turned on. If no cat stove, then you just turn the draft down. With the cat stove there can be a bigger difference between flue temperature and stove top.