Most systems have a lifetime of 10 to 15 years, with gas furnaces lasting 20-25 years. As your equipment gets older, its efficiency can decrease dramatically. You may notice that it gets noisier and needs repairs more often. If you live near bodies of water or the ocean, your system’s life expectancy may be drastically shortened due to the harsh environment. If your system is over 10 years old, you should have your system checked for maintenance or replacement.