Johnson Controls YP9C Series Installation Manual page 13

MODULATING FURNACE
WIRE
COMMUNICATING
CONNECTOR
CONTROL
A+
THERMOSTAT
C
A+
B-
R
TERMINAL
SCREW
C
B-
INDOOR UNIT
Figure 17: Terminal screw wire connection
When connecting the Communicating Control (wall thermostat) and fur-
nace control to a non-communicating outdoor A/C, use the wiring dia-
gram in Figure 16.
The thermostat and furnace are to be connected exactly as shown
above, but the conventional 24 V R, C, LOW COMP, and HI COMP ter-
minals are used to control the outdoor unit.
Control wiring using communicating controls
(variable capacity outdoor models)
The Communicating System consists of several intelligent communicat-
ing components including the Hx
nace and the modulating air conditioner or heat pump. These
components continually communicate with each other via the wire con-
nections shown in Figure 18. Commands, operating conditions, and
other data are passed continually between components over the A-R-C-
B and A-C-B bus. The result is a new level of comfort, versatility, and
simplicity.
In order to use this furnace with a variable capacity outdoor unit, it must
be installed with a communicating Hx thermostat.
Use the wiring diagram in Figure 18 to connect the furnace control
TM
and the Hx Thermostat (wall thermostat) to the communicating out-
door unit. Be sure that all of the "A+" terminals are connected together,
all of the "B-" terminals are connected together, all of the "C" terminals
are connected together and the "R" terminals from the Hx thermostat to
the indoor unit are connected together. Do NOT connect the "R" wire to
the outdoor unit. The four small screw terminals in the terminal block on
the furnace control should be used.
Important: Do not place more than one wire under any single
communication terminal screw (there are four communication
terminal screws). If more than one wire must be connected to a
terminal screw, attach only the terminal end of a one wire pigtail
no longer than 6", and use a wire connector to connect the other
end of the pigtail to the other wires. Failure to do this will result
in nuisance communication error faults. See Figure 17.
Connect a short piece of thermostat wire (18 gage minimum) to the
ARCB terminals on the furnace control board. Use wire connectors to
connect this wire to the room thermostat wire and the outdoor unit ther-
mostat wire. The outdoor unit contains its own control transformer. DO
NOT run a thermostat "R" wire to the outdoor unit. See Figure 18 for
details.
Johnson Controls Ducted Systems
NOTE
ENSURE ONLY ONE WIRE UNDER
TERMINAL SCREW.
TO CONNECT MORE THAN ONE WIRE:
1. CONNECT ONLY TERMINAL
END OF 6" WIRE PIGTAIL,
2. USE WIRE CONNECTOR TO
B-
CONNECT OTHER END OF PIGTAIL
TO OTHER WIRES.
OUTDOOR UNIT
TM
Thermostat, the variable speed fur-
Figure 18: Furnace with variable capacity AC or HP
Conventional low voltage control wiring connec-
tions
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 19 to 23. 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).
Important: Set the heat anticipator in the room thermostat to 0.1
amps. Setting it lower will cause short cycles. Setting it higher
will cause the room temperature to exceed the set points.
Important: Some electronic thermostats do not have adjustable
heat anticipators. They should be set to six cycles per hour. Fol-
low the thermostat manufacturer's instructions.
The 24 V, 40 VA transformer is sized for the furnace components only,
and should not be connected to power auxiliary devices such as humid-
ifiers and air cleaners. The transformer may provide power for an air
conditioning unit contactor.
Air conditioner connections
This furnace may be used with single-stage or two-stage air condition-
ing units.
For Single-Stage A/C - Connect the low voltage wiring as shown in
Figure 19.
For Two-Stage A/C - Use a two-stage thermostat, connect the low volt-
age wiring as shown in Figure 20.
For Two-Stage A/C using a Single-Stage Thermostat - connect the
low voltage wiring as shown in Figure 21.
This furnace control board can control a two-stage A/C using only a sin-
gle-stage thermostat. In this case, the furnace control switches between
high cool and low cool based on the calculated cooling load.
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