Our heater is 18+ years old. It is nearing the end of its useful life, but has been going strong due to regular maintenance. I appreciate the time and attention we are given for our regular maintenance appointments, and at this last apt we were notified that it is time for us to investigate replacing the heater before the next cold season when a probable failure of an expensive part could force us to make a less than ideal decision. As a homeowner, this info and advice is very helpful for planning.