I am trying to problem streamline the process for using our new Jotul insert. I am used to using a stand alone stove and am not sure why we have ended up with blackened glass doors after just a few days of use. Our wood is well seasoned (over one year) and so I am thinking that this is an issue of not burning the fire hot enough? How do I know if the fire is hot enough... is there a way to burn a smaller fire without the concern of blackening the doors and finally, how do I get the doors cleaner??