A common question that comes up frequently when inspecting properties is “How much longer will this item last before I need to replace it?”
The answer is not always easy, because the environment in which the item lives and the previous maintenance that has been performed, have an impact on its life expectancy. I like to refer to a handy chart about life expectancy, for a variety of household components.
https://www.oldhouseweb.com/how-to-advice/life-expectancy.shtml