Page 20
Installer’s Guide
Control Wiring (Class II)
Low voltage control wiring should not be run in conduit with power
wiring unless Class 1 wire of proper voltage rating is used. Route
the thermostat cable or equivalent single leads of No. 18 AWG
colored wire from the thermostat subbase terminals through the
rubber grommet on the unit. See Figures 2 or 5 for the control
entry (24V Entry) location. Make connections as shown on the
unit wiring diagram.
Do not short thermostat wires since this will damage the control
transformer.
Refer to Table 6 for recommended wire sizes and lengths for install-
ing the unit thermostat. The total resistance of these low voltage
wires must not exceed one (1) ohm. Any resistance in excess of 1
ohm may cause the control to malfunction because of the exces-
sive voltage drop.
Table 6. Thermostat Wire Size and Maximum Length
Contactor
Unit Ground Lug
Figure 20. Power Connections
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NOTE:
The 4DCL units require approved dual fuel comfort control.
Do not install any other model of thermostat with this 4DCL unit.
Otherwise, mis-operation could result.
NOTE:
See Comfort Control Guide for required sensors & jumper
add or removals.
NOTE:
The 4DCL units are equipped with an outdoor temperature
switch to limit gas operation. For outdoor temperatures above 40
degrees, heating is provided by Heat Pump operation only. For
temperatures 40 and below, heating may be provided by both gas
or Heat Pump operation.
TWO MODES OF OPERATION:
The unit can be installed and configured to operate in one of two
different heating modes: restricted and non-restricted. A brief
explanation of each mode follows.
RESTRICTED:
In the restricted mode of operation, an outdoor
temperature sensor is used to cause the unit to operate in the heat
pump mode above a selected outdoor temperature and to operate
in the gas heating mode below the selected outdoor temperature.
NOTE:
The 4DCL units are equipped with an outdoor temperature
switch to limit gas operation. For outdoor temperatures above 40
degrees, heating is provided by Heat Pump operation only.
The gas heat will operate with the heat pump when the unit
requires a defrost cycle. The gas heat is used to offset the effect
of the unit going into the cooling mode during defrost. For the
*CONT402, the unit will be commanded to transition to gas heat
even when the outdoor temperature is abobve the selected
outdoor temperature changeover oint if the heat pump capacity
is not enough to maintain the indoor tempeature at the desired
heating setpoint.
NON-RESTRICTED:
T
his mode of operation only allows the unit
to operate in the heat pump mode during the first call, or stage
of heat commanded by the indoor thermostat. If the heat pump
capacity is sufficient, gas heat will not be required. If the heat
pump capacity is not enough to maintain the indoor temperature at
the desired heating setpoint, the thermostat will call for the second
stage of heat. At that point, the gas heat will begin to operate and
the heat pump will be locked out.
NOTE:
The 4DCL units are equipped with an outdoor temperature
switch to limit gas operation. For outdoor temperatures above 40
degrees, heating is provided by Heat Pump operation only.
See the Field Wiring Diagram, page 21, for field wiring instructions.
IMPORTANT:
Upon completion of wiring, check all electrical
connections, including factory wiring within the unit. Make
sure all connections are tight. Replace and secure all
electrical box covers and access doors before leaving the
unit or turning
on the power to the unit.
NOTE:
The outdoor sensor should be located in an area which will
provide a representative outdoor ambient temperature reading.
Figure 21. Mounted Disconnect Location
Thermostat Operation
Operation of the unit heating or cooling cycles is controlled by the
comfort control. Once the system mode is set to either HEAT or
COOL, unit operation is automatic. The fan ON setting provides
continuous indoor blower operation at constant circulation -
approximately 40 - 50% of nominal airflow at selected dipswitch
settings. The AUTO setting provides indoor blower operation dur-
ing the compressor heating and cooling cycles. CONTINUOUS
fan mode during COOLING operation may not be appropriate in
humid climates. If the indoor air exceeds 60% relative humidity or
simply feels uncomfortably humid, it is recommended that the fan
only be used in the AUTO mode.
RELEASED 10/Aug/2020 16:34:00 GMT
