Rtu Open Control System; Systemvu™ (Factory Option) - Carrier WeatherExpert 50LC 07 Series Service And Maintenance Instructions

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 unit, the thermostat must be capable of ener-
gizing the G terminal (to energize the Indoor Fan Contactor)
whenever there is a space call for heat (energizing the W1 termi-
nal). 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 eight leads. If the thermostat does not require a
24-v source (no "C" connection required), use a thermostat cable
or equivalent with minimum of seven leads. Check the thermostat
installation instructions for additional features which might re-
quire 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). All wire sizes larger than no. 18 AWG
cannot be directly connected to the thermostat and will require a
junction box and splice at the thermostat. See Fig. 37.
Typical
Thermostat
Connections
C
W1
W2
G
Y3
(Note 3)
O/B/Y2
(Notes 2 & 3)
(Note 1)
Y1
R
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.
Field Wiring
Fig. 37 — Low-Voltage Connections
UNIT WITHOUT THRU-BASE CONNECTION KIT
Pass the thermostat control wires through the hole provided in the
corner post; then feed the wires through the raceway built into the
corner post to the control box. Pull the wires over to the terminal
strip on the upper-left corner of the Controls Connection Board.
See Fig. 38.
NOTE: If thru-the-bottom connections accessory is used, refer to
the accessory installation instructions for information on routing
power and control wiring.
Integrated
Staging Control
(ISC) Board
C
W1
T
H
W2
E
R
G
M
O
Y3
S
T
Y2
A
T
Y1
R
25
RACEWAY
HOLE IN END PANEL (HIDDEN)
Fig. 38 — Field Control Wiring Raceway
HEAT ANTICIPATOR SETTINGS
Set heat anticipator settings at 0.14 amp for the first stage and
0.14 amp for second-stage heating, when available.
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
from the 230-v connection and moving it to the 208-v
terminal on the primary side of the transformer. Refer to unit label
diagram for additional information.
ELECTRIC HEATERS
50LC units may be equipped with factory or field-installed electric
heaters. The heaters are modular in design, with heater frames
holding open coil resistance wires strung through ceramic insula-
tors, line-break limit switches and a control contactor. One or two
heater modules may be used in a unit.
Heater modules are installed in the compartment below the indoor
(supply) fan outlet. Access is through the indoor access panel.
Heater modules slide into the compartment on tracks along the
bottom of the heater opening. See Fig. 28-30. Refer to the Electric
Heater Kit Installation Instructions for complete details on field in-
stalled electric heat accessory.
Not all available heater modules may be used in every unit. Use
only those heater modules that are UL/ETL listed for use in a spe-
cific size unit. Refer to the label on the unit cabinet for the list of
approved heaters.

RTU Open Control System

For details on operating units equipped with the factory-installed
RTU Open controller, refer to the "Factory-Installed RTU Open
Multi-Protocol Controller Control, Start-Up, Operation and Trou-
bleshooting" manual.
SystemVu™ (Factory Option)
For details on operating units equipped with the factory installed
SystemVu control option, refer to the 48/50LC 07-26 Single
Package Rooftop Units with SystemVu Controls Version 3.X or
later Controls, Start-Up, Operation and Troubleshooting manu-
al.
/ -in. female spade connector
1
4
/ -in. male
1
4