This is not always true. The age of the HVAC unit is a good indicator as to whether or not the unit needs to be replaced. But, this isn’t always an accurate method to decide if your HVAC unit needs to be replaced. If a system is more than 8 years old may be not a good quality and should be replaced. But, a system that is 30 years old might not require to be replaced if the system has been taken care of properly. It is possible to expect the lifespan of your HVAC system to be between 15 and 20 years. One good practice is that you replace your HVAC in the event that you’ve put in significant sums of money in the system. m89kd4jsko.