1034868-UIM-A-0513
14
Johnson Controls Unitary Products
CONTROL WIRING USING COMMUNICATING
CONTROLS
Use the wiring diagram below to connect the furnace control, Communi-
cating Control (wall thermostat) and communicating outdoor unit. Be
sure that all of the “A” terminals are connected together, all of the “B”
terminals are connected together, all of the “GND” or “C” terminals are
connected together and all of the “R” terminals are connected together.
See Figure 19. When using a fully communicating system, the large
screw terminals (C, G, R, etc.) on the furnace control are not used. The
four small screw terminals in the terminal block on the end of the fur-
nace control should be used.
When connecting the Communicating Control (wall thermostat) and fur-
nace control to a non-communicating outdoor A/C or heat pump, use
the wiring diagram in Figure 20. The thermostat and furnace will be con-
nected exactly as shown above, but the conventional 24 volt R, C and
Y/Y2 terminals will be used to control the outdoor unit.
Float Switch Input
An optional switch may be connected to the FLT SWT terminals on the
control board. This feature is only functional when used with the Com-
munication Control. It is intended for use with a water overflow switch.
Auxiliary Switch Input
An optional switch may be connected to the AUX SWT terminals on the
control board. This feature is only functional when used with the Com-
munication Control. Refer to Communication Control Installation Man-
ual.
LOW VOLTAGE CONTROL WIRING CONNECTIONS
Install the field-supplied thermostat by following the instructions that
come with the thermostat. With the thermostat set in the OFF position
and the main electrical source disconnected, connect the thermostat
wiring from the wiring connections on the thermostat to the terminal
board on the ignition module, as shown in Figures 21 - 24. Electronic
thermostats may require the common wire to be connected. Apply
strain relief to thermostat wires passing through cabinet. If air condition-
ing equipment is installed, use thermostat wiring to connect the Y and C
terminals on the furnace control board to the proper wires on the con-
densing unit (unit outside).
The 24-volt, 40 VA transformer is sized for the furnace components
only, and should not be connected to power auxiliary devices such as
humidifiers, air cleaners, etc. The transformer may provide power for an
air conditioning unit contactor.
FIGURE 19:
Two-stage Furnace with Communicating AC or HP
A+
R
C
B-
A+
R
C
B-
A+
R
GND
B-
LO
COMP
HI
COMP
O
DHUM
Y1
Y/Y2
W
R
G
C
Touch Screen
Communicating control
Furnace
Communicating control
Air Conditioner/Heat Pump
Communicating control
FIGURE 20:
Two-stage Furnace with Communicating Thermostat and
Non-Communicating AC
Set the heat anticipator in the room thermostat to 0.4 amps. Setting it
lower will cause short cycles. Setting it higher will cause the room
temperature to exceed the set points.
Some electronic thermostats do not have adjustable heat anticipa-
tors. They should be set to six cycles per hour. Follow the thermostat
manufacturer's instructions.
A+
R
C
B-
A+
R
B-
LO
COMP
HI
COMP
O
DHUM
Y1
Y/Y2
W
R
G
C
Touch Screen
Communicating control
Furnace
Communicating control
Non-
Air Conditioner
Communicating
Y
Y2
R
C
C
