It is rather amazing that the central heating as well as a/c plan I have is still going strong after almost 20 years! The life span of a central heating as well as a/c plan is usually about 15 years as well as if you are lucky you can make it to the 20 year mark but it will be on its last leg. Mine is not! It is super amazing that it is still around as well as does not need to be updated at all. Even my local heating as well as a/c specialist is pretty darn amazed by all of this. I just recently had my seasonal heating as well as a/c plan tune up as well as check up too as well as the heat as well as a/c specialist from the local heating as well as cooling contractor said that it is not needing to be updated as well as has no complications what so ever. Maybe this could be a single for the book of world records as the longest living heating as well as a/c plan unit? Well, not quite yet but if it lasts another 5 or 6 years it may actually qualify. I actually do not assume what the longest living heating as well as a/c plan is, but mine has to be pretty darn close to whatever it may be. I will not question it as well as just keep on using the central heating as well as a/c plan until the day that I can not use it any longer. Who knows when that will be, but for sure it will not be any time in the near future according to what the local heating as well as cooling specialist from the local heating as well as a/c contractor said.