Table of Contents
Advertisement
LOW VOLTAGE
CONDUIT
CONNECTOR
Fig. 33 — Thru-Base Connection Fittings
UNITS WITHOUT THRU-BASE CONNECTIONS
1. Install power wiring conduit through side panel openings.
Install conduit between disconnect and control box.
2. Install power lines to terminal connections as shown in
Fig. 26.
FIELD CONTROL WIRING
The 50HCQ unit requires an external temperature control de-
vice. This device can be a thermostat (field-supplied) or a Pre-
mierLink™ controller (available as factory-installed option or as
field-installed accessory, for use on a Carrier Comfort Network
or as a 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 col-
ors with minimum of seven leads. If the thermostat does not re-
quire a 24-v source (no "C" connection required), use a thermo-
stat cable or equivalent with minimum of six leads. See Fig. 34.
Check the thermostat installation instructions for additional fea-
tures 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.
HIGH VOLTAGE
CONDUIT
CONNECTOR
Typical
Thermostat
Connections
C
G
W2
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. 34 — Typical Low-Voltage Control Connections
CENTRAL TERMINAL BOARD
The Central Terminal Board (CTB) is a pass through connection
point. The CTB provides the capability to add factory-installed
®
options and field-installed accessories to the units by cutting
jumper wires without having to change or reroute wires through
the structure of the unit. The CTB does not provide any micropro-
cessor control; it is simply a basic multifunction wiring terminal
configuration.
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. 35 for board arrangement.
The DFB is located in the 50HCQ unit's main control box (see
Fig. 2 and 36). All connections are factory-made through harness-
es 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 6 for details of DFB Inputs and Outputs.
19
Central
Terminal
Board
X
C
G
W2
(Note 2)
W1
Y2
Y1
R
T
H
E
R
M
O
S
T
A
T
Advertisement
Table of Contents
