Carrier WeatherMaker 48A020 Installation Instructions Manual page 26

T-STAT (Conventional Thermostat)
Unit can be controlled with a Carrier-approved accessory electro-
mechanical or electronic thermostat that has two stages of cooling,
two stages of heating control, and an output for indoor fan control.
It may also include time of day scheduling or use the scheduling
routines built into the ComfortLink controls.
Install thermostat according to the installation instructions includ-
ed with accessory thermostat and the unit wiring diagrams. Locate
thermostat assembly on a solid interior wall in the conditioned
space to sense average temperature.
Route thermostat cable or equivalent single leads of colored wire
from subbase terminals through conduit into unit to low-voltage
connection in the main control box. For thermostat TB4 connec-
tions see Fig. 24.
NOTE: For wire runs up to 50 ft, use no. 18 AWG (American
Wire Gage) insulated wire (35C minimum). For 50 to 75 ft, use
no. 16 AWG insulated wire (35C minimum). For over 75 ft, use
no. 14 AWG insulated wire (35C Minimum). Wire larger than no.
18 AWG cannot be directly connected at the thermostat and will
require a junction box and splice at the thermostat. Set heat antici-
pator settings as follows:
48A SIZE
020-050
060
Settings may be changed slightly to provide a greater degree of
comfort for a particular installation.
FIELD-SUPPLIED THERMOSTAT
RC Y1 Y2
R
Y1 Y2
R
1 2 3
Fig. 24 — Field Control Thermostat Wiring
Staged Gas Control Option Thermistors
If the unit is equipped with the staged gas heat option, supply-air
thermistors must be installed. Three supply-air thermistors are
shipped with staged gas units and are inside the heating section.
The supply-air thermistors should be located in the supply duct
with the following criteria:
• Downstream of the heat exchanger cells
• Equally spaced as far as possible from the heat exchanger
cells
• In a duct location where none of the supply-air thermistors
are within sight of the heat exchanger cells
• In a duct location with good mixed supply-air portion of
the unit.
SPT (Space Temperature Sensor)
For constant volume applications the ComfortLink controls can
also be used with T55 and T56 space temperature sensors that use
a 10K thermistor. The T56 sensor also has the capability for a con-
figurable temperature set point offset. For variable air volume ap-
plications only the T55 sensor can be used.
Install sensor according to the installation instructions included
with accessory sensor. Locate sensor assembly on a solid interior
wall in the conditioned space to sense average temperature. Run
wiring to the space sensor as shown in Fig. 25.
Note that when the remote sensor is used, the red jumper wires
provided must be connected from TB4 terminal 4 to 5 and TB4
terminal 5 to 1.
STAGE 1 STAGE 2
(W1) ON (W1 AND W2) ON
0.24 0.13
0.36 0.13
LIGHT
W1 W2 G C
W1 W2 G C
4 5 6 7
TB4
Both the T55 and T56 sensors have a CCN communications port
and this should be wired to the CCN Communications TB3 board
if it is desired to have access to the CCN system through the
sensor. If more than one T55 sensor is being used and averaged,
sensors must be wired in multiples of 4 or 9 as shown in Fig. 26.
UNIT
TB5
Fig. 25 — Space Temperature Sensor Wiring
TB5
RED
3
BLK
4
a48-6855
TB5
X
3
X
4
8
NOTE: Use T55 sensor only.
Fig. 26 — Space Temperature Averaging Wiring
T58 Communicating Thermostat
Carrier also has a fully communicating thermostat which, if
used, will be wired to the CCN communication connections on
TB3 as described in the Carrier Comfort Network
section below.
Carrier Comfort Network Interface
The rooftop units can be connected to the CCN system. The com-
munication bus wiring is supplied and installed in the field. Wiring
consists of shielded, 3-conductor cable with drain wire. The sys-
tem elements are connected to the communication bus in a daisy
chain arrangement. The positive pin of each system element com-
munication connector must be wired to the positive pins of the
system element on either side of it, the negative pins must be
26
T55 SPT T56 SPT
T1 C
T2 TH
1
3 5 9 11
7
2 4
8 12
6 10
SENSOR 1 SENSOR 3
SENSOR 2
SPACE TEMPERATURE AVERAGING (4 SENSOR APPLICATION)
SENSOR 1
SENSOR 2
SENSOR 5
SENSOR 4
SENSOR 8
SENSOR 7
SPACE TEMPERATURE AVERAGING (9 SENSOR APPLICATION)
SN
13
15
14 16
SENSOR 4
SENSOR 3
SENSOR 6
SENSOR 9
Interface
®