20
• The thermostat must be installed according to the
instructions supplied by the thermostat manufacturer.
Low voltage connections (24 VAC) from the thermostat
are wired to the terminal strip on the integrated control
in the furnace. Recommended minimum wire gauge for
thermostat wiring is shown in Table 2.
• The thermostat should be mounted about 5 feet
above the fl oor on an inside wall. DO NOT install the
thermostat on an outside wall or any other location
where its operation may be adversely affected by radiant
heat from fi replaces, sunlight, or lighting fi xtures, and
convective heat from warm air registers or electrical
appliances. Refer to the thermostat manufacturer’s
instruction sheet for detailed mounting information.
• Depending on the type of air conditioning unit and
thermostat used, both blower applications utilize three
basic wiring confi gurations:
Single Stage AC & Single Stage Thermostat
This option does not use the full two-stage control
capability of the furnace, but the possibility of timed
autostaging is available. See also Autostaging for Single
Stage Thermostats:
• Connect the thermostat’s
W
output to the furnace
control boards
W1
terminal. This allows the furnace to
always run in low output mode. See Figure 15.
• Always connect the thermostat
C
&
R
to the furnace
control board
C
&
R
.
• For cooling, connect the thermostat’s
Y
signal to the
furnace control board’s
Y / Y2
terminal.
• Field supplied wires should also connect
Y / Y2
&
C
to
the outdoor unit’s
Y
&
C
terminals.
Figure 15. Wiring Confi guration 1
R DHUM
C
Y
G
W
1
ROOM THERMOSTAT
(SINGLE STAGE)
DHUM
A/C CONDENSING UNIT
(SINGLE STAGE)
C
R
C
Y/Y2
Y
W2
G
W1
Y1
HIGH EFFICIENCY
BLOWER MOTOR
CONTROL BOARD
TWO STAGE FURNACE BOARD
Two-Stage AC & Two-Stage Thermostat
This option uses the full two-stage heating capability of
the furnace with a two-stage outdoor unit. See Figure 17.
• Connect the thermostat’s
W1
&
W2
outputs to the
furnace control board’s
W1
&
W2
terminals.
• Always connect the thermostat
C
&
R
to the furnace
control board
C
&
R
.
• For cooling, connect the thermostat’s
Y
&
Y1
signals to
the furnace control board’s
Y / Y2
&
Y1
terminal’s.
• Field supplied wires should also connect
Y / Y2
&
Y1
signals to the outdoor unit’s
Y
&
Y1
terminals.
• Connect terminal
C
to the outdoor unit’s
C
.
A/C CONDENSING UNIT
(TWO STAGE)
HIGH EFFICIENCY
BLOWER MOTOR
CONTROL BOARD
DHUM
C
Y2
Y1
R DHUM
C
Y
2
G
ROOM THERMOSTAT
(TWO STAGE)
W
1
W
2
TWO STAGE FURNACE BOARD
Y
1
R
C
Y/Y2
W2
G
W1
Y1
Figure 17. Wiring Confi guration 3
Autostaging for Single Stage Thermostats
The Autostaging feature included on all G7 2-stage
furnaces make it possible to use a single stage thermostat
and still receive some of the benefi ts of 2-stage furnace
operation. If Autostage is enabled, the furnace will drop to
LOW
fi re after initially starting in
HIGH
fi re. After a period
of time (8 or 12 minutes) the furnace will then stage up
to
HIGH
fi re, until the heating load is met. See Figure 15
and the Low Voltage Wiring section (page 19).
Autostaging options are selected using the autostage
jumper located near the thermostat terminal block. See
Figure 23 (page 33). When the autostage jumper is moved
from
NONE
to
SHORT
or
LONG
, the following occurs
during a call for heat:
Figure 16. Wiring Confi guration 2
DHUM
A/C CONDENSING UNIT
(SINGLE STAGE)
HIGH EFFICIENCY
BLOWER MOTOR
CONTROL BOARD
C
Y
R DHUM
C
Y
G
ROOM THERMOSTAT
(TWO - STAGE)
W
1
W
2
TWO STAGE FURNACE BOARD
R
C
Y/Y2
W2
G
W1
Y1
Single Stage AC & Two-Stage Thermostat
This option uses the full two-stage heating capability of the
furnace with a single stage outdoor unit. See Figure 16.
• Connect the thermostat’s
W1
&
W2
outputs to the
furnace control board’s
W1
&
W2
terminals.
• Always connect the thermostat
C
&
R
to the furnace
control board
C
&
R
.
• For cooling, connect the thermostat’s
Y
signal to the
furnace control board’s
Y / Y2
terminal.
• Field supplied wires should also connect
Y / Y2
&
C
to
the outdoor unit’s
Y
&
C
terminals.
