Lennox S40 - Setup and Customization Process; Initial Setup Process; Customization Process Overview; Setting Up the S40 Smart Thermostat

6
Lennox
Communicating
Outdoor Unit
Lennox
Communicating
Thermostat
Indoor Unit Communicating Control
(Using 2-conductor Unshielded Cable for Communication Lines and
Separate 2-conductor Unshielded Cable for R and C)
OPTION 3
18/2 Brown Solid CU CL2 Thermostat Wire
Figure 4. Lennox Communicating System Wiring Connections using
Separate Unshielded Cable (Option 3)
Minimizing Electrical Noise
When using multi-conductor unshielded thermostat cable, to minimize electrical
noise, cap unused wires as illustrated below and run to indoor unit C terminal.
Single wire
to indoor unit
terminal “C”.
Unused
wires
Single wire directly to
C terminal or
to second bundle.
.
Indoor Unit Controller
Outdoor Unit
Thermostat
R i+ I- C
Unused
wires
Figure 5. Minimizing Electrical Noise