MBVC Installation Manual

10
System
System Operating
Mode
Airflow Demand Source
Cooling Air Conditioner
Heating Air Handler
Continuous Fan Thermostat
Cooling Heat Pump
Heat Pump Heating
Only
Heat Pump
HP + Electric Heat
Strips
> of Heat Pump or Air
Handler Demand
Electric Heat Strips
Only
Air Handler
Continuous Fan Thermostat
Air Conditioner +
Air Handler
Heat Pump + Air
Handler
For example, assume the system is a heat pump matched
with an air handler. With a call for low stage cooling, the
heat pump will calculate the system’s low stage cooling air-
flow demand. The heat pump will then send a fan request
along with the low stage cooling airflow demand to the air
handler. Once received, the air handler will send the low
stage cooling airflow demand to the ECM motor. The ECM
motor then delivers the low stage cooling airflow. See the
applicable ComfortNet™ air conditioner or heat pump instal-
lation manual for the airflow delivered during cooling or heat
pump heating.
In continuous fan mode, the CTK0* thermostat provides
the airflow demand. The thermostat may be configured for
a low, medium, or high continuous fan speed. The low,
medium, and high fan speeds correspond to 25%, 50%,
and 75%, respectively, of the air handlers’ maximum
airflow capability. 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.
CTK0* THERMOSTAT WIRING
NOTE: Refer to section Electrical Connections for 208/230
volt line connections to the modular blower.
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 no connect
multiple wires into a single terminal. Wire nuts are
recommended to ensure one wire is used for each terminal.
Typical 18 AWG thermostat wire may be used to wire the
system components. However, communications reliability
may be improved by using a high quality, shielded, twisted
pair cable for the data transmission lines. In either case, 100
feet is the maximum length of wire between indoor unit and
outdoor unit, or between indoor unit and thermostat.
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 ther-
mostat. The required wires are: (a) data lines, 1 and 2; (b)
thermostat “R” (24 VAC hot) and “C” (24 VAC common).
12RC
12RC
CTK0*
Thermostat
CT™ Compatible
Modular Blower
Integrated Control Module
CT™ Compatible AC/HP
Integrated Control Module
12
RC
System Wiring Using Four-Wires
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.
12RC
12
RC
CTK0*
Thermostat
CT™ Compatible
Modular Blower
Integrated Control
Module
CT™ Compatible
AC/HP Integrated
Control Module
40VA Transformer
208/230 VAC
24 VAC
12RC
System Wiring using Two-Wires between Air Handler and AC/
HP and Four-Wires between Air Handler and Thermostat
COMFORTNET™ SYSTEM ADVANCED FEATURES
The ComfortNet™ system permits access to additional sys-
tem information, advanced setup features, and advanced di-
agnostic/troubleshooting features. These advanced features
are organized into a menu structure. See the following
MODULAR BLOWER ADVANCED FEATURES MENUS sec-
tion for layout of menu shortcuts.