Electrical Wiring; Two-Stage Furnace With Communicating Ac Or Hp - Johnson Controls TM9V C Series Installation Manual

5750149-UIM-D-1219
SUPPLY VOLTAGE CONNECTIONS
FIGURE 13: Electrical Wiring
1. Provide a power supply separate from all other circuits. Install over-
current protection and disconnect switch per local/national electrical
codes. The switch should be close to the unit for convenience in
servicing. With the disconnect or fused switch in the OFF position,
check all wiring against the unit wiring label. Refer to the wiring dia-
gram in this instruction.
2. Remove the wiring box cover screws. Route all power wiring
through a conduit connector or other proper bushing that is field
installed into the unit opening and the junction box. In the junction
box there is a black wire, a white wire and a green ground screw.
Connect the power supply as shown on the unit's wiring label
located on the inside of the blower compartment door, or the wiring
schematic in this section. Connect the black wire to L1 (hot) from
the power supply. Connect the white wire to neutral. Connect the
ground wire (installer-supplied) to the green (equipment ground)
screw. An alternate wiring method is to use a field-provided 2"
(5.1 cm) x 4" (10.2 cm) box and cover on the outside of the furnace.
Route the furnace leads into the box using a protective bushing
where the wires pass through the furnace panel. After making the
wiring connections replace the wiring box cover and screws. Refer
to Figure 13.
3. The furnace's control system requires correct polarity of the power
supply and a proper ground connection. Refer to Figure 13.
IMPORTANT: The power connection leads and wiring box may be
relocated to the opposite side of the furnace. Remove the screws and
cut wire tie holding excess wiring. Reposition on the opposite side of
the furnace and fasten using holes provided.
CONTROL WIRING
This furnace can be connected to the wall thermostat and outdoor A/C
or heat pump using either conventional low voltage (24 VAC) thermo-
stat wiring OR using four-wire digital communications wiring. To use
conventional low voltage wiring, see the section entitled "Conventional
Low Voltage Control Wiring". To use four-wire communications control
wiring, see the section below entitled "Control Wiring using Communi-
cating Controls".
The Communicating System consists of several intelligent communicat-
ing components including the Communicating Thermostat Control
(touch-screen wall thermostat), variable speed furnace, communicating
capable air conditionr or heat pump which continually communicate
with each other via a four-wire connection called the A-R-C-B.
Commands, operating conditions, and other data are passed continu-
ally between components over the A-R-C-B. See Figure 14. The result
is a new level of comfort, versatility, and simplicity.
In order to use this furnace in full communications (COMM) mode, it
MUST be installed with the matching touch-screen Communicating
Control (wall thermostat) and an outdoor air conditioner or heat pump
with a fully communicating control.
12
This furnace may be used with the Communicating Thermostat Control
and a non-communicating outdoor air conditioner by installing the AC
Communicating Control Board Kit to the outdoor unit. This system
allows full communication between the furnace and thermostat and lim-
ited communication to the outdoor unit. See Figure 14.
FIGURE 14: Two-stage Furnace with Communicating AC or HP
CONTROL WIRING USING COMMUNICATING
CONTROLS (NON-VARIABLE CAPACITY OUTDOOR
MODELS)
Use the wiring diagram to connect the furnace control, Communicating
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
14. When using a fully communicating system, the large screw termi-
nals (C, G, R, etc.) on the furnace control are not used. The four small
screw terminals in the terminal block on the labeled "communications"
furnace control should be used.
IMPORTANT: Do not place more than one wire under any single
communication terminal screw (there are four communication termi-
nal screws). If more than one wire must be connected, 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 16.
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-
municating Control. It is intended for use with a water overflow switch
that has contacts in either the normally open (NO) or (NC) position. Do
NOT install a float switch in series with any thermostat wiring when
using communicating controls.
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.
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