We have been burning some new pellets. Wood Fiber Pellet brand. I noticed a lot of built up ash in the flame area, but was shocked when I opened up the ash pan and it was FULL to the top after only 1 week. We have never had our ash pan more than 1/4 full after a week. I was wondering if it has anything to do with running the stove on low and idle T stat mode? Our glass was also really black and hard to clean which can be from the low heat setting too. Other than the ash, the pellets burned well, no unburned pellets, no clinkers and a nice pleasent smell when burning.