31
the ECM motor. If the outdoor unit or thermostat is respon-
sible 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 table below lists the various ComfortNet sys-
tems, the operating mode, and airflow demand source.
System
System
Operating Mode
Airflow Dem and
Source
Cooling
Air Conditioner
Heating
Furnace
Continuous Fan
Thermostat
Cooling
Heat Pump
Heat Pump Heating
Only
Heat Pump
Auxiliary Heating
Furnace
Continuous Fan
Thermostat
Cooling
Furnace
Heating
Furnace
Continuous Fan
Thermostat
F Non-
Comm 1stg Air
Conditioner
Air Condi
Furnace
Heat Pump +
Furnace
For example, assume the system is an air conditioner matched
with a furnace. With a call for low stage cooling, the air con-
ditioner 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 furnace. Once
received, the furnace 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 installation 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%, respec-
tively, of the furnaces’ maximum airflow capability. During con-
tinuous fan operation, the thermostat sends a fan request along
with the continuous fan demand to the furnace. The furnace,
in turn, sends the demand to the ECM motor. The ECM motor
delivers the requested continuous fan airflow.
F
OSSIL
F
UEL
A
PPLICATIONS
This furnace can be used in conjunction with a ComfortNet™ com-
patible heat pump in a fossil fuel application. A fossil fuel applica-
tion refers to a combined gas furnace and heat pump installation
which uses an outdoor temperature sensor to determine the most
cost efficient means of heating (heat pump or gas furnace). When
used with the CTK0* thermostat, the furnace/heat pump sys-
tem is automatically configured as a fossil fuel system. The
balance point temperature may be adjusted via the CTK0* ther-
mostat advanced user menus (see CTK0* instructions for addi-
tional information).
CTK0* W
IRING
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 18 AWG 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 sys-
tem components. One hundred (100) feet is the maximum
length of wire between indoor unit and outdoor unit, or between
indoor unit and thermostat. Wire runs over (100) feet require
larger gauge wire.
F
OUR
-W
IRE
I
NDOOR
AND
O
UTDOOR
W
IRING
Typical ComfortNet 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).
1
2
R C
1
2
R C
CTK0*
Thermostat
ComfortNet Compatible Furnace
Integrated Control Module
ComfortNet Compatible AC/HP
Integrated Control Module
1
2
R C
System Wiring using Four-Wires
T
WO
-W
IRE
O
UTDOOR
, F
OUR
-W
IRE
I
NDOOR
W
IRING
Two wires can be utilized between the indoor and outdoor units.
For this wiring scheme, only the data lines, 1 and 2, are needed
required between the indoor and outdoor units. A 40VA, 208/
230 VAC to 24VAC transformer must be installed in the out-
door unit to provide 24VAC power to the outdoor unit’s elec-
tronic control. See the instruction manual provided with the
thermostat for wiring instructions.
