Goodman ComfortNet ASXC Series Service Instructions Manual page 37

SERVICING
between the thermostat and subsystems (indoor/outdoor
unit) and between subsystems is the key to unlocking the
benefits and features of the ComfortNet system.
Two-way digital communications is accomplished using
only two wires. The thermostat and subsystem controls are
powered with 24 VAC Thus, a maximum of 4 wires between
the equipment and thermostat is all that is required to operate
the system.
AIRFLOW CONSIDERATIONS
Airflow demands are managed differently in a fully communi-
cating system than they are in a legacy wired system. The
system operating mode (as determined by the thermostat)
determines which unit calculates the system airflow demand.
If the indoor unit is responsible for determining the airflow
demand, it calculates the demand and sends it to the ECM
motor. If the outdoor unit or thermostat is responsible for
determining the demand, it calculates the demand and
transmits the demand along with a fan request to the indoor
unit. The indoor unit then sends the demand to the ECM
motor. The following table lists the various ComfortNet™
systems, the operating mode, and airflow demand source.
For example, assume the system is an air conditioner
matched with an air handler. With a call for low stage cooling,
the air conditioner will calculate the system's low stage
cooling airflow demand. The air conditioner 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. The
table below lists the nominal high and low stage airflow for the
ComfortNet air conditioners and heat pumps.
Cooling
Models
High
*SZC160241 800
*SZC160361 1200
*SZC160481 1550
*SZC160601 1800
*SZC180241 850
*SZC180361 1250
*SZC180481 1750
*SZC180601 1750
Heating
Low High Low
600 800 600
800 1200 800
1100 1550 1100
1210 1800 1210
550 850 550
850 1250 850
1210 1750 1210
1210 1750 1210
CONTROL WIRING
NOTE: Refer to section Electrical Connections - High
Voltage Connections for 208/230 volt line connections to
the air conditioner or heat pump.
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. 150 feet is the maximum length of wire
recommended between indoor unit and outdoor unit, or
between indoor unit and thermostat.
CTK04 STANDARD WIRING SCHEME:
Two wires may be utilized between the indoor and outdoor
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. The "C" 24v common of the outdoor
transformer should be grounded to the equipment (earth)
ground. The transformer is included with the CTK0* kit. See
kit instructions for mounting and wiring instructions. Four
wires are required between the indoor unit and thermostat.
40VA Transformer (included in
CTK04 kit)
208/230 VAC 24 VAC
System Wiring
Thermostat
1 2 R C
Air Handler/Furnace/PCB
1 2 R C
AC/HP/ PCB
1 2 R C
(Ground Indicator)
Note: Recommended (Field Provided)
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