What the others have said. Mine is 3 years old and looks like new inside also. The condition of your water will have an affect on life but little you can do about it. I have very bad iron in my water but run a softener and use soft water in the OWB, change it every year and add chemicals per the manual. Clean, dry and oil works for the fire chamber over the summer. Dos not have to be squeeky clean but you need to get rid of enough creosote so the oil isnt laying on top of it. I have 4 OWBs near me and at least 3 of them get nothing besides shut down over the summer, one dude does even cover his stack. In a few years when they are spending big bucks for replacements I am going to feel pretty smug about the 2 hours a year I spend maintaining mine.