The square footage of your home and your individual comfort needs are important factors in determining the best HVAC unit for your home. Choosing a system that is too small may not produce enough heating and cooling and the system will have to work harder resulting in an additional cost to you. Because undersized units have to work harder and run a lot more—breakdowns are more common. A system that is too large may generate more heating or cooling than is needed in shorter periods of time. The goal is to select the size you need so your system is effective, efficient, and affordable.