20
maximum airflow capability. If the thermostat provides four continuous fan speeds then a 100% airflow option is added. During
continuous fan operation, the thermostat sends a fan request along with the continuous fan demand to the air handler. The
air handler, in turn, sends the demand to the ECM motor. The ECM motor delivers the requested continuous fan airflow.
20.2 CTK0* Thermostat Wiring
NOTE:
Refer to section Electrical Connections for 208/230 volt line connections to the air handler
.
NOTE:
A removable plug connector is provided with the control to make thermostat wire connections. This plug may be
removed, wire connections made to the plug, and replaced.
It is
STRONGLY
recommended that you do not connect
multiple wires into a single terminal. Wire nuts are recommended to ensure one wire is used for each terminal.
Failure to do so may result in intermittent operation.
Typical 18 AWG thermostat wire may be used to wire the system components. One hundred (100) feet is the maximum
length of wire between indoor unit and outdoor unit, or between indoor unit and thermostat.
20.3 Four-Wire Indoor and Outdoor Wiring
Typical wiring will consist of four wires between the indoor unit and
outdoor unit and between the indoor unit and thermostat. The required
wires are: (a) data lines, 1 and 2; (b) thermostat “R” (24 VAC hot) and
“C” (24 VAC common).
20.4 Two-Wire Outdoor, Four-Wire Indoor Wiring
Two wires only may be utilized between the indoor and out-
door units. For this wiring scheme, only the data lines, 1 and
2, are required between the indoor and outdoor units. A
40VA, 208/230 VAC to 24 VAC transformer must be installed
in the outdoor unit to provide 24 VAC power to the outdoor
unit’s electronic control. See kit instructions for mounting and
wiring instructions. Four wires are required between the in-
door unit and thermostat.
20.5 ComfortNet™ System Advanced Features
The ComfortNet system permits access to additional system information, advanced set-up features, and advanced diagnos-
tic/troubleshooting features. These advanced features are organized into a menu structure. See the AIR HANDLER AD-
VANCED FEATURES MENU section for layout of menu shortcuts.
20.6 Diagnostics
Accessing the air handler’s diagnostics menu provides ready access to the last six faults detected by the air handler. Faults
are stored most recent to least recent. Any consecutively repeated fault is stored a maximum of three times. Example: A
clogged return air filter causes the air handler’s motor to repeatedly enter a limiting condition. The control will only store this
fault the first three
consecutive
times the fault occurs.
NOTE:
It is highly recommended that the fault history be cleared after performing maintenance or servicing the air handler
.
20.7 Network Troubleshooting
The ComfortNet system is a fully communicating system, and thus, constitutes a network. Occasionally the need to trouble-
shoot the network may arise. The integrated air handler control has some on-board tools that may be used to troubleshoot
the network. These tools are: red communications LED, green receive (Rx) LED, and learn button. Refer to the
Communi-
cations Troubleshooting Chart
at the end of this manual for error codes, possible causes and corrective actions
•
Red communications LED – Indicates the status of the network. The table below indicates the LED status and the
corresponding potential problem.
1
2
R
C
1
2
R
C
CTK0*
Thermostat
CT™ Compatible
Air Handler Blower
Integrated Control Module
CT™ Compatible AC/HP
Integrated Control Module
1
2
R C
System Wiring Using Four-Wires
Figure 33
1
2
R C
1
2
R C
CTK0*
Thermostat
CT™ Compatible
Air Handler Blower
Integrated Control
Module
CT™ Compatible
AC/HP Integrated
Control Module
40VA Transformer
208/230 VAC
24 VAC
1
2
R C
System Wiring using Two-Wires between Air Handler and AC/
HP and Four-Wires between Air Handler and Thermostat
Figure 24