Every appliance you use has a lifespan, even if it promises to serve you to infinity. The only thing is that it can serve you for years because of the superb manufacturing that goes into it, but at one point, it will fail when the part finally wears out beyond repair. This also happens to HVAC units because they are mechanical and electrical appliances. The manufacturer may promise you years of service when you purchase their brand, but several conditions are pegged to such longevity promises and claims. You need to stick to these maintenance requirements to get the most out of the unit. Even so, there comes a time when the HVAC system gives up, and it requires an upgrade. In such cases, consider replacing the unit immediately and preferably go for higher quality or the latest technology in the industry. But when should you start worrying about replacing the HVAC unit? Well, the first sign that should prompt you to consider replacing your HVAC system is sudden hikes in energy bills. If you suddenly have to deal with higher energy bills that seem to come out of the blues, then you need to change it. Discuss with your HVAC specialist first because there could be other different triggers behind the sudden increase in energy use and cost. However, if none exists, this is a clear indication that the unit is no longer as effective as before. Another reason you need to change your unit is when you find yourself constantly having to call the HVAC business for recommendations on parts to replace. This means that your HVAC technician has to visit at least once every month to carry out some major HVAC repairs. Such are simple cues that you should never ignore.