SYSTEM OPERATION
30
Thermostat connections to the control board are R, C, G,
W, Y & Dehum. Provided the thermostat does not require a
common wire as few as two thermostat wires may be used
for heat only (R and W) or cool only (R and Y) systems. A
minimum three thermostat wires may be used for heating
and cooling systems (R, W and Y). Refer to thermostat wiring
diagrams below for your system configuration.
Low voltage connections can be made through either the right
or left side panel of the furnace. Thermostat wiring entrance
holes are located in the blower compartment.
Thermostat
Communica
�
ng Outdoor Unit
Condensate
Switch
MAIN CONTROL BOARD
For gas heat only operations (no outdoor unit installed) the
thermostat must be setup to provide a single stage W call
when heating is required. See Gas Heat Only wiring diagram
for wiring instructions.
R
C
G
Y
Optional
Optional
INDOOR
BOARD TERMINAL
CONNECTIONS
R
C
G
Y
24 VAC
Thermostat
1
2
C
GAS HEAT ONLY
LOW VOLTAGE WIRING - COMMUNICATING
OUTDOOR UNIT
Internal logic will control staging of all multi stage equipment (2
stage AC/HP units and Inverter AC/HP units). The thermostat
is only required to provide a single stage heat / cool call and
fan or dehumidification call during operation.
Two wires are required between the indoor unit and outdoor
unit on the 1 and 2 terminals. It is recommended to install a
separate transformer with all 2 stage outdoor units to reduce
the power draw on the indoor transformer.
4 wires (R,C for power and 1, 2 for communications) can be
used for AC applications. See wiring images for details.
Do not connect R & C between the indoor unit and the outdoor
unit if there is already a transformer installed in the outdoor
unit providing 24VAC to the outdoor control. In this case, just
use 1 and 2 terminals for communications.
R
C
G
Y
Optional
Optional
Optional if
feature
supported by
thermostat
INDOOR
BOARD TERMINAL
CONNECTIONS
OUTDOOR
BOARD TERMINAL
CONNECTIONS
OUTDOOR
TRANSFORMER
1
2
C
R
C
G
Y
1
2
C
COMMUNICATING TWO STAGE AIR
CONDITIONER OR HEAT PUMP
1
2
C
R
C
G
Y
Optional
Optional
Optional if
feature
supported by
thermostat
INDOOR
BOARD TERMINAL
CONNECTIONS
OUTDOOR
BOARD TERMINAL
CONNECTIONS
1
2
C
R
C
G
Y
24 VAC
Thermostat
COMMUNICATING INVERTER
AIR CONDITIONER OR HEAT PUMP
LOW VOLTAGE WIRING - NON-COMMUNICATING
OUTDOOR UNIT