If you for example have a triple net lease, and it is time to return the building to the owner (depending on how exactly your lease is written) you are most likely responsible for the upkeep, and maintenance of the building and its amenities. This typically includes the major appliances, and you might think that since they all work fine that there is no legal obligation you can be stuck with. BUT, this can be misleading in the common sense world because all major appliances have a recognized expected effective age that describes how long they are expected to last, and when they are expected to be replaced. The last phrase is key, in that even if a major appliance (i.e. roof mounted furnace, or any HVAC units) is working fine, but it is older than its expected effective you can be held liable for its replacement even though it works fine. This is really for a reason though because once a unit is beyond its effective age there are other components that its older operation can negatively affect. If you don’t get an inspection, or at least know when these appliances are due to be replaced, and your owner does, you could be held liable for anything that is beyond its expected effective age. The photo shows an ID plate on an A/C unit that does work, and is into its 30th year of operation, but its effective age was up long ago.