26
TWIN TERMINAL
BLOWER
CONTROL
BOARD
W
G
Y
C
R
FURNACE
BOARD
TWIN TERMINAL
BLOWER
CONTROL
BOARD
Expansion
Po
rt
W
G
Y
C
R
FURNACE
BOARD
THERMOSTAT
W1
G
Y
R
AC
UNIT
W2
6-Pin Wiring
Harness
6-Pin Wiring
Harness
RELAY
COM
NO
PRIMARY FURNACE
SECONDARY FURNACE
Expansion
Po
rt
Expansion
Po
rt
Expansion
Po
rt
C
RED
WHITE
TWIN TERMINAL
BLOWER
CONTROL
BOARD
W
G
Y
C
R
FURNACE
BOARD
TWIN TERMINAL
BLOWER
CONTROL
BOARD
Expansion
Po
rt
W
G
Y
C
R
FURNACE
BOARD
THERMOSTAT
W1
G
Y
R
W2
6-Pin Wiring
Harness
6-Pin Wiring
Harness
RELAY
COM
NO
PRIMARY FURNACE
SECONDARY FURNACE
Expansio
n
Po
rt
Expansio
n
Po
rt
Expansion
Po
rt
C
RED
WHITE
SINGLE STAGE HEATING (WITH TWINNING)
TWO STAGE HEATING (WITH TWINNING)
AC
UNIT
Figure 29. Nordyne/UTEC Single & Two Stage
Twinning
• Both furnaces must have a common return duct and
common supply plenum.
• Both furnaces must be the same phase and on the same
leg of power.
• Furnaces equipped with variable speed iSEER™
motors may not be twinned under any circumstances.
For twinning of single stage furnaces equipped with
and the following
instructions:
1. Turn off all power to both furnaces.
2. Attach a wire between the two twin terminals on the blower
control boards. Use field supplied wire and 3/16” wire
terminals.
NOTE:
One furnace can be used for one stage of heating
and the other furnace can be used for the second stage of
heating. The installer also has the choice of running one
furnace only or both furnaces. In both cases the blowers will
run at the same time and at the same speeds:
One stage heating
• Connect the thermostat wires to the primary furnace
control board. Mount the relay on the bracket on the
secondary furnace.
• Connect
W
from the primary furnace to the coil side of the
relay (using field supplied wire and 3/16” terminals).
• Connect
C
from the primary furnace to the coil side of
the relay (using field supplied wire and 3/16” terminals).
NOTE:
Make sure connections are made on opposite
sides of the coil.
• Connect
R
from the secondary furnace control board to
the COM side of the relay (use included
red
wire).
• Connect
W
from the secondary furnace control board to
NO
side of the relay (use included white wire).
Two stage heating
• Connect the thermostat wires to the furnace control
board (except W2). Mount the relay on the bracket on the
secondary furnace.
• Connect
W1
from the thermostat control to
W
of the
primary furnace.
• Connect
W2
from the thermostat to the coil side of the
relay (using field supplied wire and 3/16” terminals)
• Connect
C
from the primary furnace to the coil side of the
relay (using field supplied wire and 3/16” terminals).
NOTE:
Make sure connections are made on opposite
sides of the coil
• Connect
R
from the secondary furnace control board to
the COM side of the relay (use included
red
wire).
• Connect
W
from the secondary furnace control board to
NO
side of the relay (use included white wire).
Heat Anticipator
Set the heat anticipator according to the instructions supplied
by the thermostat manufacturer. To determine the heat
anticipator setting:
1. Add the current draw of the system components; or
2. Measure the current flow on the thermostat
R
-
W
circuit
after the circulating blower motor has started.
PRIMARY FURNACE
SECONDARY FURNACE
R C Y G W
TWIN
TERMINAL
FURNACE
BOARD
Y R G W C
TWIN
TERMINAL
FURNACE
BOARD
Y R G
W1
C
W2
THERMOSTAT
AC
UNIT
COM
NO
RELAY
TWO STAGE HEATING (WITH TWINNING)
WHITE
PRIMARY FURNACE
SECONDARY FURNACE
R C Y G W
TWIN
TERMINAL
FURNACE
BOARD
Y R G W C
TWIN
TERMINAL
FURNACE
BOARD
Y R G
W1
C
W2
THERMOSTAT
AC
UNIT
COM
NO
RELAY
SINGLE STAGE HEATING (WITH TWINNING)
WHITE
Figure 30. Emerson Single & Two Stage
Twinning
