A C wire adapter, also known as a common wire adapter, is an accessory used in HVAC systems to provide a dedicated power source, specifically a C wire or common wire, to a thermostat that requires it. It is designed to address situations where a C wire is not readily available in the existing wiring setup. How does a C wire adapter work A C wire adapter (common wire adapter) works by adding a new C wire to the thermostat by repurposing the existing wiring between the thermostat and the furnace. A typical C wire adapter has 4 terminals at the input to connect the wires from the furnace, and five wires at the output; to connect to the thermostat. This fifth wire will serve as the C wire or common wire to provide the necessary power to the thermostat. Which wires are repurposed to add the new C wire…