Comfort Sync A3 - Page 6

6
Table 2. Smart Hub Terminal Designations, Order and Wiring
Requirements
Terminal
Designation
Description Thermostat Wiring
R 24VAC input 18AWG unshielded
I+ RS-BUS I+
22AWG shielded (recommended)
(2-pair conductor only)
I- RS-BUS I-
C 24VAC return 18AWG unshielded
ACC1 Accessory 1 and 2 (typically can be
used for 1 or 2 speed ventilators and
fresh air damper)
18AWG unshielded
ACC2
12+
12VDC output 18AWG unshielded
A
Communications bus A
22AWG shielded (recommended)
(2-pair conductor only)
B
Communications bus B
12-
12VDC return 18AWG unshielded
IMPORTANT
Use 2-pair, 18AWG unshielded thermostat cable (eld-provided) for power terminals (R, C, 12+
AND 12-). Recommend using 2-pair 22AWG shielded thermostat cable for communications
terminals (I+, I-, A and B) which will help eliminate any noise interference.