These systems are designed to last a long time with good maintenance. Many home owners do not realize their home heating and air conditioning system operates approximately 3,600 hours per year. To put this “run time” in perspective, a car driven for the same 3,600 hours at 65 miles per hour would travel 234,000 miles or around the earth ten times. No one would consider such a journey without arranging for oil changes, lubrication, and routine tune-ups along the way to assure the efficiency, safety and reliability of the vehicle.
Manufacturers typically give a 12-15 year life span, the system often last up to 15-20 years. The tension in deciding to replace is to compare the efficiency of the old system and its expected repair cost versus the improved efficiency of the proposed unit and its lower expected maintenance. At some point keeping an older system is more expensive that replacing it.
In our experience most HVAC systems last between 15 and 20 years, but specific components of the system can actually give out long before then. All component lifetimes are highly variable and depend on whether the system is properly maintained throughout its lifetime. Lack of regular air conditioning and heating maintenance can lead to lower efficiency and much larger problems which may require the HVAC system to be replaced. Furnaces and boilers generally run in the 15 to 20 year range, and heat recovery ventilators can run even longer, but the heat pumps that these parts rely on tend to last 16 years at most.
On the other hand, air conditioners run between 10 and 15 years. Dehumidifiers are not expected to last beyond 8 years and ventilators beyond 7 years, making these parts the shortest-lived components in an HVAC system. The thermostat will usually last a good long time, but the new ones are so much better due to rapid improvements that have been made in HVAC control systems over recent years.