41
FIELD CONTROL WIRING
The 50LC size 14-26 units require an external temperature control
device such as a thermostat (field-supplied).
THERMOSTAT
Install a Carrier approved accessory thermostat according to in-
stallation instructions included with the accessory. For complete
economizer function and 3-stage compressor operation select a
three-stage cooling thermostat. If a 3-stage cooling thermostat is
not available, use a 2-stage cooling thermostat instead, but note
that this will limit cooling to just 2 stages. When electric heat is in-
stalled in the 50LC size 14-26 units, the thermostat must be capa-
ble of energizing the G terminal (to energize the Indoor Fan Con-
tactor) whenever there is a space call for heat (energizing the W1
terminal). The accessory thermostats listed on the unit price pages
can provide this signal but they are not configured to enable this
signal as shipped.
Locate the thermostat accessory on a solid wall in the conditioned
space to sense average temperature in accordance with the ther-
mostat installation instructions.
If the thermostat contains a logic circuit requiring 24-v power, use
a thermostat cable or equivalent single leads of different colors
with minimum of seven leads. If the thermostat does not require a
24-v source (no “C” connection required), use a thermostat cable
or equivalent with minimum of six leads. See Fig. 57. Check the
thermostat installation instructions for additional features which
might require additional conductors in the cable.
For wire runs up to 50 ft. (15 m), use no. 18 AWG (American
Wire Gage) insulated wire [35°C (95°F) minimum]. For 50 to
75 ft. (15 to 23 m), use no. 16 AWG insulated wire [35°C (95°F)
minimum]. For over 75 ft. (23 m), use no. 14 AWG insulated wire
[35°C (95°F) minimum]. Wire sizes larger than no. 18 AWG can-
not be directly connected to the thermostat and will require a junc-
tion box and splice at the thermostat.
Fig. 57 — Low-Voltage Thermostat Connections
UNITS WITHOUT THRU-BASE CONNECTION KIT
Correctly rated low voltage wire can be routed through the rubber
grommet located on the corner post adjacent to the control box ac-
cess panel. Route wire through the grommet and then route the
wire behind the corner post utilizing the factory provided wire ties
secured to the control box. This will ensure separation of the field
low voltage wire and the high voltage circuit. Route the low volt-
age wire to the Integrated Staging Control (ISC) board. See
Fig. 58.
NOTE: If utilizing the through the base connections, route the low
voltage wire through the wire ties to the ISC board.
Fig. 58 — Field Control Wiring Raceway
CONFIGURING FOR ELECTRIC HEAT
To configure the factory-approved thermostat, open the Advanced
Setup menu, scroll down to ELECTRIC HEAT and change
RANGE value from OFF to ON. Consult the thermostat installa-
tion instructions for full details.
HEAT ANTICIPATOR SETTINGS
Set heat anticipator settings at 0.14 amp for the first stage and
0.14 amp for second-stage heating.
TRANSFORMER CONNECTION FOR 208-V POWER
SUPPLY
All units except 208/230-v units are factory wired for the voltage
shown on the nameplate. If the 208/230-v unit is to be connected
to a 208-v power supply, the control transformer must be rewired
by moving the black wire with the
1
/
4
-in. female spade connector
from the 230-v connection and moving it to the 208-v
1
/
4
-in. male
terminal on the primary side of the transformer. Refer to unit label
diagram for additional information.
C
G
C
G
O/B/Y2
Y2
R
R
Y1
Y1
Y3
Y3
(Note 1)
(Notes 2, 3 & 4)
(Note 3 & 4)
W1
W1
W2
W2
T
H
E
R
M
O
S
T
A
T
Note 1: Typical multi-function marking. Follow manufacturer’s configuration
Instructions to select Y2.
Note 2: Y2 to Y3 connection required for 2-stage cooling operation and when
integrated economizer function is desired.
Note 3: To Connect a 2-Stage Thermostat:
Y2 to Y3 connection required for 2-stage cooling operation which
provides low and high cooling states.
Note 4: SystemVu
controller is default configured for 3-stage cooling and
2-stage heating thermostats; it can be configured for other thermostat types.
Field Wiring
Integrated Staging Control
(ISC) Board or
SystemVu
TM
Controller
Typical
Thermostat
Connections
RUBBER
GROMMET
CORNER
POST
WIRE
TIES
THRU THE BASE
CONNECTION
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