hi everyone first time posting on here a lot of smart people. I recently bought a used 52 bay wood insert. It has brand new cats new gaskets around the door, the guy I bought it from went through it and did a really good job. The problem I have is Appalachian says this thing has a 15 hour burn time, I can get anything more than 6 and that's with 3 big Oak logs at 15-20% moisture. Anyone have any ideas what could be wrong, or is this just a case of false advertisement. Thanks