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FIELD CONTROL WIRING
The 50HCQ unit requires an external temperature control device.
This device can be a thermostat (field-supplied) or a Premier-
Link™ controller (available as factory-installed option or as field-
installed accessory, for use on a Carrier Comfort Network
stand-alone control) or the RTU Open Controller for Building
Management Systems using non-CCN protocols (RTU Open is
available as a factory-installed option only).
THERMOSTAT
Select a Carrier-approved accessory 2-stage Cooling/Heating ther-
mostat. The 50HCQ models do not require a thermostat with an O
function to control the reversing valve operation. If using an elec-
tronic thermostat, configure it for "non-heat pump" operation. In-
stall the accessory thermostat according to installation instructions
included with the accessory.
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. 31. 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.
Typical
Thermostat
Connections
C
G
W2
(Note 2)
W1
O/B/Y2
(Note 1)
Y1
R
NOTES:
1. Typical multi-function marking. Follow manufacturer's configuration
instructions to select Y2. Do not configure for O output.
2. W2 connection not required on units without electric heating.
Field Wiring
Fig. 31 — Typical Low-Voltage Control Connections
Thermostat Wiring, Units 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. 32.
®
or as a
Central
Terminal
Board
X
C
T
H
G
E
R
W2
M
O
W1
S
T
Y2
A
T
Y1
R
19
NOTE: If thru-the-bottom connections accessory is used, refer to
the accessory installation instructions for information on routing
power and control wiring.
RACEWAY
HOLE IN END PANEL (HIDDEN)
Fig. 32 — 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.
COMMERCIAL DEFROST CONTROL
The Commercial Defrost Control Board (DFB) coordinates ther-
mostat demands for supply fan control, 1 or 2 stage cooling, 2
stage heating, emergency heating and defrost control with unit op-
erating sequences. The DFB also provides an indoor fan off delay
feature (user selectable). See Fig. 33 for board arrangement.
Fig. 33 — Defrost Control Board Arrangement
The DFB is located in the 50HCQ unit's main control box (see
Fig. 34). All connections are factory-made through harnesses to
the unit's CTB, to IFC (belt-drive motor) or to ECM (direct-drive
motor), reversing valve solenoids and to defrost thermostats. Refer
to Table 3 for details of DFB Inputs and Outputs.
DIP
SWITCHES
SPEED-UP
JUMPERS
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