There are a lot of different components in any given HVAC system. For the most part, you are not going to interact directly with the majority of these components. One very obvious exception to this rule is your thermostat in Des Moines, IA.
Your thermostat is the central control hub of your HVAC system, and it is responsible for relaying the information you put into it to your HVAC system itself. Without a great thermostat, you cannot expect great comfort. That is why you may want to upgrade yours.