Service Manual

41
In continuous fan mode, the CTK0* thermostat provides the
airflow demand. The CTK02**, CTK03 and CTK04 thermo-
stats may be configured for one of threecontinuous fan speed
settings allow for 25%, 50% or 75% airflow, based on the
furnaces’ maximum airflow capability. During continuous
fan operation, the thermostat sends a fan request along
with the continuous fan demand to the furnace. The fur-
nace, in turn, sends the demand to the ECM motor. The
ECM motor delivers the requested continuous fan airflow.
FOSSIL FUEL APPLICATIONS
This furnace can be used in conjunction with a ComfortNet™
compatible heat pump in a fossil fuel application. A fossil fuel
application refers to a combined gas furnace and heat pump
installation which uses an outdoor temperature sensor to deter-
mine the most cost efficient means of heating (heat pump or
gas furnace). The balance point temperature may be ad-
justed via the CTK0* thermostat advanced user menus (see
CTK0* instructions for additional information).
CTK0* WIRING
NOTE: Refer to Electrical Connections for 115 volt line
connections to the furnace.
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.
Multiple wires imust be twisted together prior to inserting into
the plug connector. 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 be-
tween indoor unit and thermostat. Wire runs over (100) feet
require larger gauge wire.
FOUR-WIRE INDOOR AND OUTDOOR WIRING
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).
12RC
12RC
CTK01 / 02
Thermostat
ComfortNet Compatible Furnace
Integrated Control Module
ComfortNet Compatible
Integrated Control Module Straight Cooling
12RC
System Wiring using Four-Wires
TWO-WIRE OUTDOOR, FOUR-WIRE INDOOR WIRING
Two wires can be utilized between the indoor and outdoor units.
For this wiring scheme, only the data lines, 1 and 2, are needed
between the indoor and outdoor units. A 40VA, 208/230 VAC to
24VAC transformer must be installed in the outdoor unit to pro-
vide 24VAC power to the outdoor unit’s electronic control. The
transformer is included with the CTK01AA, CTK03 and CTK04
kits. See kit instructions for mounting and wiring instructions.
If using a CTK02 or CTK01BA, an accessory transformer is
available (TFK01). Four wires are required between the in-
door unit and thermostat.
NOTE: Use of the outdoor transformer is recommended if
installing a dual fuel/fossil fuel system with a CTK01/2, or
anytime when using a CTK03 / 04 thermostat. Failure to use
the transformer in the outdoor unit could result in over loading
of the furnace transformer.
1
ST
STAGE COOLING – CONVENTIONAL THERMOSTAT
A call for cooling is signaled by:
R powering Y1 and O simultaneously
R powering Y1, O and G simultaneously
The compressor and condenser fan are energized di-
rectly from the Y1 terminal from the thermostat.
The circulator is energized after cool fan on delay.
If the ‘2 Stage Cooling’ DIP switch is set to:
ON, then circulator will run at low cooling speed with
Y1 request
OFF, then circulator will run at high cooling speed
with Y1 request (a Y2 request will be ignored)
The circulator will operate according to one of the
selectable ramping profiles.
When the cool request is satisfied, the circulator is
de-energized per one of the selectable ramping pro-
files.
2
ND
STAGE COOLING – CONVENTIONAL THERMOSTAT
The ‘2 Stage Cooling’ DIP switch on the IFC must be
ON to enable 2 stage cooling control with a conven-
tional thermostat.
A call for 2
nd
stage cooling is signaled by the shorting
of R to Y2 while a valid call for first stage cooling
exists.
After the cool fan on delay, the circulator is ener-
gized at the low cooling speed when the 1
st
stage cool
request is detected and switches to high cooling speed
immediately after the 2
nd
stage cool request is de-
tected.
The circulator will be controlled according to the se-
lected ramping profile.
When the cool requests are satisfied, the circulator
is de-energized per the selected ramping profile.
OPERATION