Water heaters in general have an average estimated useful service life of 10-12 years, though water quality, routine upkeep/maintenance, and location of the water heater will all play critical roles in the longevity of these systems.

Instantaneous or "Tankless" water heaters in general have an average estimated useful service life of 15-20 years, though water quality, routine upkeep/maintenance, and location of the water heater will all play critical roles in the longevity of these systems.

Gas-fired forced air furnaces in general have an average estimated useful service life of 15-20 years, though routine upkeep/maintenance, and location of the furnace will all play critical roles in the longevity of these systems.

Split system air conditioners and heat pumps in general have an average estimated useful service life of 10-12 years, though routine upkeep/maintenance, regional weather/climate, and location of the condenser unit will all play critical roles in the longevity of these systems.

The average service design life of boilers can vary from as little as 10 years to as many as 50 years depending on the type and quality of materials used in their manufacture. Routine upkeep/maintenance, regional weather/climate, and location/placement of the mechanical systems will all play critical roles in the longevity of these systems.

The average service design life of RTU's can vary from 10 to 15 years. Diligent upkeep and maintenance can extend the service at 15-20 years, though 20 years is typically pushing the envelope for these systems. The inherent design of some of these packaged (heating and cooling) systems can cause the heat exchanger to fail (become compromised) in as little as 2 to 5 years after installation.  Routine upkeep/maintenance, regional weather/climate, configuration of the system, and location/placement of the mechanical systems will all play critical roles in the longevity of these systems.

The average service design life of typical Geothermal systems can vary from 20 to 30 years.  Routine upkeep/maintenance, regional weather/climate, configuration of the system (open vs. closed loop), and location/placement of the mechanical systems will all play critical roles in the longevity of these systems.

Commercial chillers can be separated into two categories: air-cooled and water-cooled systems. The average service design life of typical Water-cooled Chiller systems can vary from 20 to 30 years.  The average service design life of typical Air-cooled Chiller systems is significantly less, and can vary from 15 to 20 years. It's not uncommon to encounter 45+ year old chillers still in operation, though they likely have had numerous repairs and retrofits over their service life. Additionally, the cost of operation and maintenance of these aging Chiller systems often exceeds the cost saving benefits of replacing with newer more efficient Chiller technology. Routine upkeep/maintenance, regional weather/climate, configuration of the system, and location/placement of the mechanical systems will all play critical roles in the longevity of these systems.

The average service design life of typical Cooling Towers can vary from 15-20 years, though ASHRAE has determined that Cooling Towers now can last between 20 to 35 years when properly maintained.  It's not uncommon to encounter 45+ year old Cooling Towers still in operation, though they likely have had numerous repairs or refurbishing over their service life. Refurbishing can extend the service life up to 15 years, though the cost of operation and maintenance of these aging Cooling Towers often exceeds the cost saving benefits of replacing with newer more efficient Cooling Tower technology. Routine upkeep/maintenance, regional weather/climate, operating conditions, water quality, water treatment application, and configuration of the system will all play critical roles in the longevity of these systems.

The average service design life of typical Packaged Terminal Air Conditioners (PTACs) can vary from 10 to 15 years. Routine upkeep/maintenance, regional weather/climate, and operating conditions will all play critical roles in the longevity of these systems.