new to pellet stove.got a harman xxv in september,for 5 months kept feed setting on #4 and worked fine.tried a few premium pellets(okanaga,turman,hamers,barefoots)same thing keeps happening.i set feed on #4.for 2-3 hrs it runs fine,1 inch ash lip on burnpot.then after 3hrs i have to turn feed down to 3 or i will get unburned pellets over the edge.2-3hrs of #3 i have to turn feeder down to #2 or same issue.eventually i get feed setting to 1.5 or i will get unburned pellets falling over edge.this has happened on all 5 of the pellets i have tried.the issue is the stove on feed setting 1.5 produces way less heat than on setting 4.i go from 72 degrees on first floor to 66.i am giving the stove a thorough cleaning every 5 days