CTK04 ADDENDUM
83
CTK04** COMFORTNET
TM
THERMOSTAT
OVERVIEW
The ComfortNet™ system (or CT system) is a system that includes
a ComfortNet compatible modular blower heat pump condenser
with a CTK04** thermostat. The table below compares the valid
CT systems.
CT compatible Air Handler
or Modular Blower
CT compatible
Heat Pump Unit
Full CT system
benefits &
features
A ComfortNet heating/air conditioning system differs from a legacy/
traditional system in the manner in which the indoor unit, out-
door unit and thermostat interact with one another. In a tradi-
tional system, the thermostat sends commands to the indoor and
outdoor units via analog 24 VAC signals. It is a one-way commu-
nication 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 thermostat
comprising a ComfortNet system “communicate” digitally with
one another. It is now a two-way communications path. The
thermostat still sends commands to the indoor and outdoor units.
However, the thermostat may also request and receive informa-
tion from both the indoor and outdoor units. This information
may be displayed on the CT 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 thermostat and sub-
systems (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.
CTK04 WIRING
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 more than two wires into a
single terminal in the field because there is a risk of the wires
becoming loose. 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 im-
proved by using a high quality, shielded, twisted pair cable for the
data transmission lines. In either case, 250 feet is the maximum
length of wire between indoor unit and outdoor unit, or between
indoor unit and thermostat. Please use a thermostat model later
than CTK04AE.
TWO-WIRE O UTDOOR, FOUR-WIRE INDOOR W IRING
Low voltage wiring consists of two wires between the indoor unit
and outdoor unit and four wires between the indoor unit and the
thermostat. The required wires are: (a) data lines, 1 and 2; (b)
thermostat “R” (24 VAC hot) and “C” (24 VAC common).
12RC
12R
C
Air Handler Blower,
Gas Furnace or Module Blower
Integrated Control Module
125 . (*)
(*) Allowable Maximum Length
Outdoor unit
Integrated Control Module
250 . (*)
12RC
Communica ng Thermostat
(IncaseofCTK04AE)
System Wiring
System Wiring Using Four-Wires
Two wires only 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.
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