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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.
Figure 21. Wiring Confi guration 1
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.
Figure 22. Wiring Confi guration 2
24
Y
HIGH EFFICIENCY
C
BLOWER MOTOR
CONTROL BOARD
A/C CONDENSING UNIT
(SINGLE STAGE)
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.
A/C CONDENSING UNIT
Figure 23. Wiring Confi guration 3
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.
Y2
HIGH EFFICIENCY
Y1
C
BLOWER MOTOR
CONTROL BOARD
(TWO STAGE)
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