Newbie question here so bear with me. I understand the theory of letting the wood completely burn to coals before adding more wood to the firebox, but it seems as though the fan starts cycling while there are still very large chunks still glowing strong. This is after approx. 5 hours. I have been spreading the coals evenly and reloading at this point. Is this the correct way to do it or should I be waiting even longer before adding more wood? Does this sound like an average burn time cycle with this medium sized insert or can I be doing something differently. I am using a mixture of oak, maple, and ash splits for wood. The air control lever is probably 95% closed. Thanks for any input or suggestions.