24
Figure 21. 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
Figure 22. 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
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 23. Wiring Confi guration 3
Wiring Confi gurations
Depending on the type of air conditioning unit and
thermostat used, both blower applications utilize three
basic wiring confi gurations:
Single Stage AC and Single Stage Thermostat (Fig. 21)
This option does not use the full two-stage control
capability of the furnace, but the possibility of timed
autostaging is available. See Autostaging for Single Stage
Thermostats.
• Connect the thermostat’s
W
output (Figure 21) to the
furnace control boards
W1
terminal. This allows the
furnace to always run in low output mode.
• Always connect the thermostat
C
and
R
to the furnace
control board
C
and
R
.
• For cooling, connect the thermostats
Y
signal to the
furnace control board
Y/Y2
terminal.
• Field supplied wires should also connect
Y/Y2
and
C
to the outdoor unit’s
Y
and
C
terminals.
Two-Stage AC and Two-Stage Thermostat (Fig. 23)
This option uses the full two stage heating capability of
the furnace with a two stage outdoor unit:
• Connect the thermostat’s
W1
and
W2
outputs to the
furnace control board’s
W1
and
W2
terminals.
• Always connect the thermostat
C
and
R
to the furnace
control board
C
and
R
.
• For cooling, connect the thermostat
Y
and
Y1
to the
furnace control board’s
Y/Y2
and
Y1
terminal’s.
• Field supplied wires should also connect the
Y/Y2
and
Y1
signals to the outdoor unit’s
Y
and
Y1
terminals.
• Connect terminal
C
to the outdoor unit’s
C
.
Single Stage AC and Two Stage Thermostat (Fig. 22)
This option uses the full two stage heating capability of
the furnace with a single stage outdoor unit:
• Connect the thermostat’s
W1
and
W2
outputs to the
furnace control board’s
W1
and
W2
terminals.
• Always connect the thermostat
C
and
R
to the furnace
control board
C
and
R
• For cooling, connect the thermostats
Y
signal to the
furnace control board
Y/Y2
terminal.
• Field supplied wires should also connect
Y/Y2
and
C
to the outdoor unit’s
Y
and
C
terminals.
Autostaging for Single Stage Thermostats
The Autostaging feature included on all G7 2-stage
furnaces makes 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 start in
low fi re, but after a period of time jump to high fi re, until the
heating load is met. See Low Voltage Wiring (page 25).
Autostaging options are selected using the Autostage
jumper (Figure 31, page 41) located near the thermostat
screw terminal block. On the circuit board, Autostage
jumper pins are electrically connected on the circuit board
to
R
,
W1
, and
W2
such that:
1. When the Autostage jumper is in the “SHORT” position,
R
is connected to
W2
. Setting the Autostage jumper
in the “SHORT” position is the same as jumping
R
to
W2
. This connection signals the control to utilize an 8
minute delay between low fi re and high fi re when a call
for heat is supplied via 24V signal to
W1
.
2. When the Autostage jumper is in the “LONG” position,
W1
and
W2
are connected. Setting the Autostage
jumper in the “LONG” position is the same as jumpering
W1
and
W2
together. The control board knows that
Autostaging (at 12 minutes, the “LONG” setting) is active
when 24vac inputs from both
W1
and
W2
are received
at the same time.
