What is the Best Way to Wire a Fully Communicating System?

The diagram below illustrates how the Daikin Installation Manual (IOM) shows a fully communicating system should be wired. As the IOM shows, our preferred wiring method is for the thermostat to connect first to the Electronic Expansion Valve (EEV), then to the furnace or air handler (AHU), and finally to connect the condensing unit at the furnace/AHU. This approach eliminates the need for additional wire connectors and ensures only two wires are connected per Phoenix plug terminal. Using more than two wires per Phoenix terminal or more than three wires per connector can result in poor electrical contact, leading to communication issues.

We also strongly recommend using shielded, stranded wire for all communication circuits. Since DC voltage travels along the outer surface of the conductor and AC voltage travels through the center, the increased surface area of stranded wire enhances communication voltage transmission and overall system reliability.

Author: Tony Crowley, Technical Service Manager, Stevens Equipment Supply