Heating, ventilation, and air conditioning (HVAC) is the technology of indoor and vehicular environmental comfort. Its goal is to provide thermal comfort and acceptable indoor air quality. HVAC system design is a subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics and heat transfer. Homeowners use heaters and air conditioners to keep their homes comfortable in cold or hot weather. Some even use their HVAC systems daily. However, your units will eventually encounter problems from efficiency and... read full review »