The answer to 'how long will HVAC system last' is that most HVAC systems have a lifespan of 15-25 years with proper maintenance. The actual lifespan can vary depending on the quality of the equipment, how often it's used, and how well it's maintained by the homeowner.
Factors that can affect an HVAC system's longevity include the climate, how often the system runs, and whether the system has been properly sized for the home. Routine maintenance like changing air filters, cleaning coils, and tuning up the system annually can help extend its lifespan. Replacing worn parts proactively can also prevent breakdowns and prolong the system's useful life.