It is a good idea to have them in order to supply fresher, healthier air. In order to achieve the same results, an old HVAC system is required to be operated for longer periods and more often than a modern HVAC system. The home and the family you live in is at risk of low-quality HVAC, mold, mildew or unsafe system components. People looking to buy a home should think about HVAC systems when purchasing a home. Buyers will be aware of the necessity for a replacement HVAC systemand might decide to decline an offer. wcfejl3yjs.