SYSTEM OPERATION
49
ComfortNet System
O
VERVIEW
The ComfortNet system is a system that includes a
ComfortNet compatible furnace and air conditioner or heat
pump with a CTK0*** thermostat. A valid ComfortNet sys-
tem could also be a compatible furnace, CTK0*** thermo-
stat and non-compatible, single stage air conditioner. Any
other system configurations are considered invalid
ComfortNet systems and must be connected as a tradi-
tional (or legacy) system (
see Electrical Connections
for
wiring connections).
A ComfortNet heating/air conditioning system differs from
a legacy/traditional system in the manner in which the in-
door unit, outdoor unit and thermostat interact with one
another. In a traditional system, the thermostat sends com-
mands to the indoor and outdoor units via analog 24 VAC
signals. It is a one-way communication path in that the
indoor and outdoor units typically do not return information
to the thermostat.
On the other hand, the indoor unit, outdoor unit, and ther-
mostat comprising a ComfortNet system “communicate”
digitally with one another. It is now a two-way communica-
tions path. The thermostat still sends commands to the
indoor and outdoor units. However, the thermostat may
also request and receive information from both the indoor
and outdoor units. This information may be displayed on
the ComfortNet thermostat. The indoor and outdoor units
also interact with one another. The outdoor unit may send
commands to or request information from the indoor unit.
This two-way digital communications between the thermo-
stat and subsystems (indoor/outdoor unit) and between sub-
systems 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 power with 24 VAC. Thus, a maximum of 4 wires be-
tween the equipment and thermostat is all that is required
to operate the system.
O
PERATIONS
W
ITH
CTK03A* & CTK04A*
1. Humidification Options are ON / OFF with the CTK03AB.
When “On” is selected, the humidification relay on the
furnace control board will function during a heat call if a
humidity demand exists. Selecting “Off” means the
humidification relay will not function.
2. If the CTK03A* or CTK04A* are set up so the compres-
sor off delay is 0 min, the thermostat will display a cool
/ heat call immediately regardless of the delay built into
the outdoor unit control board. This means the CTK03A*
or CTK04A* could show COOL ON when the outdoor
unit is still in a delay period. The recommendation is to
set up the compressor delay to at least 3 minutes
3. Dual Fuel – When the CTK03A* or CTK04A* calls for
gas heat, the heat pump will shut off, after a delay of
approximately 3 minutes it will then turn on gas heat.
ComfortNet™ System
4. Dehumidification (lowering of CFM to 85%) only happens
during low stage cooling operation. The dehumidification
feature is not active during high stage cool. The CTK03A*
and the CTK04A* can be set up to overcool the home in
order to reach the RH set point.
CTK0*** W
IRING
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.
It is
strongly
recommended that multiple wires into a single
terminal 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
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.
F
OUR
-W
IRE
I
NDOOR
AND
O
UTDOOR
W
IRING
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).
1
2
R
C
1
2
R C
1
2
R C
CTK0***
Thermostat
ComfortNet Compatible Furnace
Integrated Control Module
ComfortNet Compatible AC/HP
Integrated Control Module
T
WO
-W
IRE
O
UTDOOR
, F
OUR
-W
IRE
I
NDOOR
W
IRING
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 24VAC transformer must be installed
in the outdoor unit to provide 24VAC power to the outdoor
unit’s electronic control. The transformer is included with
the CTK01A* kit. See kit instructions for mounting and wir-
ing instructions. Four wires are required between the indoor
unit and thermostat.
