SMART Si Wiring Requirements

Wiring Requirements

The following table shows the maximum wire lengths allowed:

Thermostat to HVAC Equipment                18 AWG                 20 AWG                22 AWG

                                                                       128 m/380 ft          80 m/240 ft         50 m/150 ft


Terminal  Description and Electrical Ratings

Terminal                                                                Description                                     Voltage                                 Current (Max)

N/C                                                                         Unused                                             N/A                                        N/A

Y                                                                             1st stage compressor                       24VAC                                  2A

W (O/B)  or reversing valve changeover                1st stage heating                              24VAC                                  2A                                                                                  or reversing valve changeover

G                                                                              Fan                                                  24VAC                                  2A

RC                                                                           Cool transformer *                            24VAC                                  2A

RH                                                                           Heat transformer *                            24VAC                                 2A

C                                                                              Common                                          24VAC                                  2A

Y2                                                                            2nd stage compressor                     24VAC                                  2A

W2 (AUX)                                                                2nd stage heating or 1st aux            24VAC                                 2A  


* Factory jumper installed between RC and RH. Remove jumper for 2-transformer applications. See wiring diagrams for additional information.