Thanks for your help to find some answers to the burn pot problem in the Harmon PB105 boiler and PF 100 pellet furnace by participating in this poll. It seems to happen only to this burn pot. Same part number used in both units. The Harmon stoves don't use this burn pot and I've not seen any posts with this problem in their stoves. The problem shows up as a hump forming in the middle of the burn pot air holes above the igniter location and deteriorates to cracks between the air holes. It seems to appear in my unit once or twice a during burning season. Other owners are also having this problem. But some are not. Maybe the reason for the difference can be found and a fix determined from the posts in this poll. Good information would be how owners run their PB105s and PF100s, settings, install, and what ever info. might help. Please don't vote in the poll if your PB105 or PF100 is new and has not run for at least a full season. It would be helpful to know wether or not you are having the problem and post information about how you run your unit.