Think of multi-stage HVAC equipment as having multiple settings, such as “low,” “medium,” and “high”. Single-stage HVAC equipment simply has “on” or “off”. The aim of multi stage equipment is to provide a more comfortable home while staying highly energy efficient. You can tell whether you have multi-stage heating or cooling by looking at the wiring: if there is only one wire for heating and one wire for cooling, you have a single-stage system. If you have multiple wires, you could have one of several types of multi-stage HVAC systems.