How long should it last…? I get this question a lot when selling or installing a heating or air conditioning unit.  I understand they want me to say 20, 30, 40 years and that may or may not be the answer.  You see it does have a little to do with the equipment but more to do with a question I have not asked.  “How well are you going to take care of it?  Are you going to ensure the filters are changed regularly?  Are you going to have maintenance performed regularly?  Are you going to keep the condenser coil cleaned? Are you going to call me immediately if something starts making noise?  Are you going to work on this yourself?  Are you…?  Things you take care of last longer than those you don’t.