where i work they installed a pellet pro stove with 320lb hopper,in a 40x25 showroom. just been running stove for a little bit and cant seem to get air mixture right. starts out as manual says as having a popcorn effect and pops pellets out of burn tray.glass gets very black after 2-3hrs.when set on highest number of 4, flame is only about 4-6 inches high and lazy in my opinion.have moved dampner level as manual says and as pellet pro tech says,but not changing much of anything.also tried unhooking outside air tube but no change. if giving more air it pops out of pellet tray and wastes unburned pellets.less air seems to be better but not right.this is a new stove this year,im a rookie so any help is a blessing