SYSTEM OPERATION
10
Low Voltage Wiring - General Information
The Furnace functions with any thermostat that can be
configured to provide 24VAC on Y for cooling calls and
24VAC on W for Heating calls. Based on these simple
inputs, internal algorithms will decide how to control two
stages of furnace heat in addition to any single or multi
stage outdoor heating / cooling operation (the algorithms
will handle dual fuel multi-stage systems as well). The
thermostat must be setup to provide only a Y call when
cooling is required and only a W call when heating is
required. This is generally accomplished by selecting
single stage heat / single stage cool mode during setup
(if setup is required). Do not set thermostat to heat pump
operation as system will not operate properly.
Note: The only exception is if a single stage non-
communicating Heat Pump is connected to the
furnace. Refer to Non-Communicating Single
Stage Heat Pump diagram for details.
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
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
