8
Wiring
t
ermInals
and
W
IrIng
r
ecommendatIons
Communicating systems requires four thermostat wires
between the
PureAir
S
and the Lennox Communicating
Indoor Control. When a thermostat cable with more
than four wires is used, the extra wires must be properly
connected to avoid electrical noise. The wires must not be
left disconnected. See “Figure 10. Communicating and Low
Voltage Connections”.
IMPORTANT
Use 1-pair, 18AWG unshielded thermostat cable (field-
provided) for power terminals (R and C). We highly
recommend using 18 - 22AWG shielded thermostat cable
for communications terminals (I+ and I-) which will help
eliminate any noise interference.
Table 4.
Terminal Designations and Wiring
Recommendations
Terminal
Designation
Description
Recommended
Thermostat
Wiring
R
24VAC input
18AWG unshielded
C
24VAC return
I+
RS-BUS I+
18 - 22AWG
shielded
I-
RS-BUS I-
• Use wire nuts to bundle the unused wires at each end of
the cable. A single wire should then be connected to the
indoor unit end of the wire bundle and attached to the “C”
terminals.
• Keep all communication wiring as far away from the
house electrical wiring and large electrical appliances as
possible. Recommended minimal distance is 15 feet (5
meters).
Unused wires
Single wire
to terminal “C”.
Indoor Unit Controller
PureAir
S
Figure 10. Communicating and Low Voltage
Connections
IMPORTANT
Do not connect low voltage wiring to the PureAir
S
until you
confirm the S30 thermostat has thermostat / Smart Hub
control software version 03.40.xxxx or higher software.
To update S30 thermostat follow the check for update
procedures outlined in service and application note ACC-
18-05.
c
ommUnIcatIon
W
IrIng
r
oUtIng
Communication wiring to the indoor unit is routed through
the opening in the top of the cabinet as illustrated below.
Route communication wiring through
grommet to indoor unit
iComfort Communicating
PCO Control
Figure 11. Routing of Communication Wiring
P
Ure
a
Ir
S
I
nternal
f
actory
W
IrIng
The should be wired in accordance with national and local
codes.
KEY COMPONENT
DS1 UVA LAMP / LAMPHOLDER
P15 PLUG
R15 RECEPTACLE
L31 BALLAST
J12 JACK
FB1 FERRITE BEAD
A17 MAIN SENSOR BOARD
A18 UVA SENSOR BOARD
W19 INTERCONNECT WIRE
LEGEND
Figure 12. PCO Wiring Schematic
