The R terminal in a standard thermostat wiring scheme is connected to the ______ of the 24V control transformer.

The R terminal in a standard thermostat wiring scheme is connected to the ______ of the 24V control transformer.

• A. outdoor unit
• B. high-voltage power supply
• C. 24V control transformer (secondary)
• D. energy management module

Answer: (C)

The R terminal is the hot side of the 24V control supply. In a standard thermostat circuit, the transformer provides 24V across its secondary, and R takes that live 24V to the thermostat. The thermostat then switches this supply to W, Y, or G to energize heating, cooling, or fan circuits. The other side of the transformer secondary, the common (C), completes the circuit back to the loads. So R is connected to the 24V control transformer’s secondary, not to the outdoor unit, the high-voltage primary, or an energy-management module.

The R terminal is the hot side of the 24V control supply. In a standard thermostat circuit, the transformer provides 24V across its secondary, and R takes that live 24V to the thermostat. The thermostat then switches this supply to W, Y, or G to energize heating, cooling, or fan circuits. The other side of the transformer secondary, the common (C), completes the circuit back to the loads. So R is connected to the 24V control transformer’s secondary, not to the outdoor unit, the high-voltage primary, or an energy-management module.