[adrianN]

Most residential systems have a warranty for 25 years. The manufacturer guarantees that there is no significant degradation for that time. That probably means that they last a lot longer than that.

[dsfyu404ed]

Or it means they enter the steep part of the bathtub curve at 26yr

[themitigating]

Wouldn't it be smarter to have a warranty period end further from a significant increase in the probability of failure?