Field Control Wiring - Carrier WeatherMaker 48A020 Installation Instructions Manual

% Voltage Imbalance= 100x
This amount of phase imbalance is satisfactory as it is below the maxi-
mum allowable 2%.
IMPORTANT: If the supply voltage phase imbalance is more than 2%,
contact your local electric utility company immediately.
NOTE: Check all factory and field electrical connections for tightness.
Unit failure as a result of operation on improper line voltage or
excessive phase imbalance constitutes abuse and may cause dam-
age to electrical components.
On 208/230-v units, transformers 1-5 are wired for 230-v. If 208/
230-v unit is to be run with 208-v power supply, the transformers
must be rewired as follows:
For transformer 1 move the black wire connected to terminal H2
and connect it to terminal H3.
For transformers 2-4, used for the 24-volt control circuits, connect
as follows:
1. Remove cap from red (208 v) wire.
2. Remove cap from spliced orange (230 v) wire. Disconnect
orange wire from black unit power wire.
3. Cap orange wire.
4. Splice red wire and black unit power wire. Cap wires.
If the unit is equipped with the optional convenience outlet con-
nect the yellow wire to H2 on transformer 5.
IMPORTANT: BE CERTAIN UNUSED WIRES ARE
CAPPED. Failure to do so may damage the transformers.
FIELD CONTROL WIRING — The 48A Series units support a
large number of control options that can impact the field control
wiring.
The control options that the unit can provide relate to the follow-
ing parameters:
• CV (constant volume), VAV (variable air volume), SAV™
(staged air volume), VVT
perature) or Carrier TEMP system control operation.
• Standalone with a thermostat (CV) or with a space sensor
(CV and VAV)
• Network application with CCN (Carrier Comfort Net-
work ® ) or other networks
• Demand controlled ventilation with CO
• Economizer and economizer with changeover control
• Staged gas heat
• Building and duct static pressure control
• Fire shutdown and smoke control
• Diagnostics and monitoring
For constant volume applications a thermostat (T-Stat) or space
temperature sensor (SPT) will be required.
T-STAT (Conventional Thermostat) — Unit can be controlled
with a Carrier-approved accessory electro-mechanical or electron-
ic 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
included with accessory thermostat and the unit wiring diagrams.
Locate thermostat assembly on a solid interior wall in the condi-
tioned 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 (35°C minimum). For 50 to 75 ft,
use no. 16 AWG insulated wire (35°C minimum). For over
4
= 1.78%
227
(variable volume variable tem-
®
sensor
2
75 ft, use no. 14 AWG insulated wire (35°C 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 anticipator settings as follows:
48A SIZE
020-050
060
Settings may be changed slightly to provide a greater degree of
comfort for a particular installation.
a48-8243
FIELD-SUPPLIED THERMOSTAT
RC Y1 Y2
R
Y1 Y2
R
1 2
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 follow-
ing 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 appli-
cations 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 configurable temperature set
point offset. For variable air volume applications 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.
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 sen-
sor. If more than one T55 sensor is being used and averaged, sen-
sors must be wired in multiples of 4 or 9 as shown in Fig. 26.
T55 SPT
T1
T2
a48-6854
1
3 5
UNIT
TB5
2 4
6
Fig. 25 — Space Temperature Sensor Wiring
25
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
3 4 5 6 7
TB4
T56 SPT
C
TH SN
13
9 11
7
8
10 12 14
X
X
8
15
16