What does the "r" terminal provide in an HVAC system?

The "r" terminal in an HVAC system is responsible for providing 24VAC power to various components of the system, particularly the thermostat. The "r" stands for "red" as it is typically associated with the red wire in the thermostat's wiring system. This terminal is energized with 24 volts AC, which comes from the transformer within the system.

The importance of the "r" terminal lies in its role as the main power supply point for the thermostat, enabling it to control heating and cooling functions by sending signals to the furnace, air conditioning unit, and other components based on the thermostat's settings. Understanding this function helps technicians effectively troubleshoot issues related to power supply and thermostat operation in HVAC systems.

For clarity, while other terminals in an HVAC system may manage different functions or safety protocols, the "r" terminal is specifically designated for providing constant 24VAC power.